@article{hanson_xiao_charrette_hayes_2024, title={A preliminary NASA compliant conformal coating for optimized space radiation shielding configurations and its mass attenuation coefficients}, volume={169}, ISSN={["1878-4224"]}, DOI={10.1016/j.pnucene.2024.105089}, abstractNote={As polymer applications and popularity grow in various contemporary industries, they are also being developed as matrices for high atomic number (Z) fillers in the field of radiation protection. Before a specific composite material can be a feasible radiation shield, it must first have defined and validated radiation shielding properties. This allows expected performance levels to be incorporated into material selection and design. The primary metric of photon shielding worth is mass attenuation coefficient. This report provides mass attenuation coefficients for two attractive metal oxide polymer composite options for energies ranging from 123 keV to 1.2 MeV, based on high Z and availability with low cost. The addition of tungsten oxide filler shows an effective way to improve X Ray shielding worth by multiple factors at the 123–247 keV energy range versus pure polyurethane coating or versus Aluminum. Similarly, gadolinium oxide infusion also effectively improves X Ray shielding worth in this energy regime. These samples featured exceptional homogeneity that allowed for performance levels to match theoretical calculations. With the low cost of the metal oxide powder and polyurethane coating, these materials show promise as cost-effective radiation shielding for various applications.}, journal={PROGRESS IN NUCLEAR ENERGY}, author={Hanson, Samuel C. and Xiao, Yue and Charrette, Ryan and Hayes, Robert B.}, year={2024}, month={Apr} }
 @article{holyk_hayes_2024, title={Demonstrating a Quantitative and Systematic Approach to Reducing Excess Conservativism in Nuclear Criticality Safety Analyses}, ISSN={["1943-748X"]}, url={https://doi.org/10.1080/00295639.2024.2323866}, DOI={10.1080/00295639.2024.2323866}, journal={NUCLEAR SCIENCE AND ENGINEERING}, author={Holyk, Sharbrenai Anise and Hayes, Robert B.}, year={2024}, month={Apr} }
 @article{hayes_sawyers_2023, title={A thermal natural uranium breeder reactor for large and small applications with passive safeguard designs}, volume={163}, ISSN={["1878-4224"]}, url={https://doi.org/10.1016/j.pnucene.2023.104804}, DOI={10.1016/j.pnucene.2023.104804}, abstractNote={This research explored a novel reactor design capable of hyper-breeding, potentially greater than any design previously evaluated (fast or thermal). Reactor breeding estimates at power were predicted to exceed 1.55 (Hayes, 2006) using only natural uranium making it of substantial interest for obtaining a high burnup fuel cycle. It has also been shown capable of starting with only natural uranium (NU) fuel making it highly attractive from a non-proliferation or small modular reactor (SMR)/microreactor perspective. The breeding capability also allows for partial refuelling with depleted uranium (DU) with a new core burnup capability >3 GW yr (Hayes, 2007, 2008). Previous scoping calculations demonstrated great promise having only evaluated metallic, unclad slab fuel geometries without considerations for material performance after irradiation or the thermal hydraulics of such a system. This work reviews the technical basis for such a neutron economy where reactor physics considerations demonstrate how such a heterogenous configuration enables apparently drastic changes in reactor performance. These changes subsequently create the potential for application in SMR/microreactor technology such that high enriched low assay uranium (HALEU), and its associated inherent limitations, may not be necessary. In addition, novel non-proliferation technology is also considered which could further mitigate closed fuel cycle models for this reactor concept by providing passive monitoring capabilities such that the design incorporates multiple layers of safety and security. Overall, the technology here argues for a novel set of technologies making for passively non-proliferation safe nuclear reactors.}, journal={PROGRESS IN NUCLEAR ENERGY}, author={Hayes, Robert B. and Sawyers, Matthew J.}, year={2023}, month={Sep} }
 @article{sewell_hayes_2023, title={An Assessment of Heterogeneous Effects on System Reactivity for Criticality Safety Analyses with LEU+ and HALEU Materials}, volume={209}, ISSN={0029-5450 1943-7471}, url={http://dx.doi.org/10.1080/00295450.2022.2157662}, DOI={10.1080/00295450.2022.2157662}, abstractNote={Abstract To develop the criticality safety basis for any system, process, or package, the worst-case configuration of materials resulting in the maximum system reactivity must be determined. It is commonly accepted that in terms of the maximum system reactivity, at the lower enrichments used in current commercial practice (i.e., 5 wt% 235U), a heterogeneous configuration is bounding of a homogeneous mixture of fissile and moderating materials. However, a common assumption made is that with increasing enrichment, a homogeneous system can be bounding. With increased industry interest in utilizing higher enrichments for commercial applications with low-enriched uranium (LEU+) (≤10 wt% 235U), and high assay low-enriched uranium (HALEU) (≤20 wt% 235U) materials, it has become increasingly important to verify any assumptions and to have a better understanding of the expected system behavior at these higher enrichments. The SCALE code system was used to assess the effects of heterogeneity on system reactivity with varying enrichments and system configurations for a UO2 and water system, typical of a transportation package criticality analysis. The purpose of this assessment was to provide insight on the effect of material heterogeneity on system reactivity with increasing enrichment. The results of this study confirm that for systems with a higher hydrogen-to–fissile material (H/X) ratio, the homogeneous mixture of material may be bounding for HALEU materials. However, for systems with a lower hydrogen-to–fissile material ratio (H/X ≤ 200), a heterogeneous configuration of contents is expected to be bounding for most LEU materials. Overall, for any LEU system, including HALEU material, heterogeneous reactivity effects should always be considered.}, number={6}, journal={Nuclear Technology}, publisher={Informa UK Limited}, author={Sewell, Philip H. and Hayes, Robert B.}, year={2023}, month={Feb}, pages={835–856} }
 @article{tsorxe_hayes_2023, title={Dose Estimation for Extravasation of 177Lu, 99mTc, and 18F}, volume={124}, ISSN={1538-5159 0017-9078}, url={http://dx.doi.org/10.1097/HP.0000000000001653}, DOI={10.1097/HP.0000000000001653}, abstractNote={Abstract Extravasation is the situation in which a nuclear medicine injection deposits some fraction of its radioactivity into the soft tissue rather than the bloodstream and may result in a large local radiation dose to tissue. An understanding of localized radiation dose from such unexpected events can be an important aspect of clinical radiation protection. The aim of this study was to estimate and assess absorbed radiation dose to localized soft tissue for hypothetical scenarios of radiopharmaceutical extravasation. Specifically, the goal was to understand whether a radiopharmaceutical extravasation could exceed the US Nuclear Regulatory Commission’s medical event reporting limit of 0.5 Sv dose equivalent to tissue or levels at which tissue damage would be anticipated (1.0 Sv dose equivalent). We used the GATE Monte Carlo simulation software to calculate self-dose to spherical volumes containing uniformly distributed amounts of common radiopharmaceutical isotopes. Simulated volumes, radioactivity levels, and effective half-lives represented real-world nuclear medicine procedures. Chosen scenarios consisted of 50 mCi and 100 mCi 177Lu within 20 cm3 and 40 cm3 tissue volumes and a 60 min biological clearance half-time (59.6 min effective half-life), 6 mCi and 12 mCi 99mTc within 1 cm3 and 5 cm3 tissue volumes and a 120 min biological clearance half-time (90 min effective half-life), and 3 mCi and 6 mCi 18F within 1 cm3 and 5 cm3 tissue volumes with a 30 min biological clearance half-time (23.6 min effective half-life). We calculated absorbed doses to be between 5.5 Gy and 23.5 Gy for 177Lu, between 0.9 Gy and 12.4 Gy for 99mTc, and between 1.5 Gy and 16.2 Gy for 18F. Radiopharmaceutical extravasations can result in tissue doses that surpass both medical event reporting limits and levels at which deterministic effects are expected. Radiation safety programs should include identification, mitigation, dosimetry, and documentation of significant extravasation events.}, number={3}, journal={Health Physics}, publisher={Ovid Technologies (Wolters Kluwer Health)}, author={Tsorxe, Innocent Y. and Hayes, Robert B.}, year={2023}, month={Mar}, pages={217–220} }
 @article{long_hayes_2023, title={EVALUATION OF EXISTING PUBLIC DOSE LIMITS APPLIED TO RECREATIONAL SPACEFLIGHT}, volume={199}, ISSN={0144-8420 1742-3406}, url={http://dx.doi.org/10.1093/rpd/ncad037}, DOI={10.1093/rpd/ncad037}, abstractNote={Establishing realistic radiation dose limits with a solid scientific basis is a key component of the 'as low as reasonably achievable' (ALARA) principle. Although existing occupational dose limits have been established for civil astronauts, with the rise in popularity and technological maturation of the 'space tourism' sector, there does not appear to be considerable discussion on the subject of non-occupational astronaut dose limits. The necessity to come to a collective decision on dose limits and radiation safety procedures for recreational spaceflight is urgent and imperative to maintain ALARA goals, as existing federal dose limits to the public cannot be adequately or universally applied to the space tourism sector. Development of an entirely new set of regulations and guidelines should also provide long-term benefits in public perception as evidence of safety commitments from decision makers and the community in protecting passengers from radiological risks balanced with other spaceflight hazards.}, number={5}, journal={Radiation Protection Dosimetry}, publisher={Oxford University Press (OUP)}, author={Long, Michael A and Hayes, Robert B}, year={2023}, month={Feb}, pages={482–489} }
 @article{wainwright_powell_hoover_ayoub_atz_benson_borrelli_djokic_eddy-dilek_ermakova_et al._2023, title={Nuclear waste Educator's workshop: What and how do we teach about nuclear waste?}, volume={270}, ISSN={["1879-1700"]}, DOI={10.1016/j.jenvrad.2023.107288}, abstractNote={A workshop was held at the Massachusetts Institute of Technology (MIT) on July 25th and 26th, 2022. The objective was to develop a blueprint for educating next-generation engineers and scientists about nuclear waste management and disposal, which requires knowledge from diverse disciplines, including nuclear, chemical, civil, environmental, and geological science and engineering. The 49 participants included university professors, researchers, industry experts, and government officials from different areas. First, we have developed a list of key fundamental knowledge on waste management and disposal across the nuclear fuel cycle. In addition, we discussed strategies on how to teach students with diverse backgrounds through innovative teaching strategies as well as how to attract students into this area. Through the workshop, we identified the critical needs to (1) develop community resources for nuclear waste education; (2) synthesize historical perspectives, including past contamination and the management of general hazardous waste; (3) emphasize a complete life-cycle perspective, including proper waste management as the key component for energy sustainability; (4) teach students how to communicate about the key facts and risks to technical and non-technical audiences; and (5) accelerate the use of the state-of-art-technologies to attract and retain a young workforce. Furthermore, we aim to build a diverse, inclusive community that supports students in developing their own narratives about nuclear waste, particularly in recognizing that antagonistic views have been important to improving safety and protecting public health and the environment.}, journal={JOURNAL OF ENVIRONMENTAL RADIOACTIVITY}, author={Wainwright, Haruko Murakami and Powell, Brian A. and Hoover, Megan Elisabeth and Ayoub, Ali and Atz, Milos and Benson, Craig and Borrelli, R. A. and Djokic, Denia and Eddy-Dilek, Carol Ann and Ermakova, Dinara and et al.}, year={2023}, month={Dec} }
 @article{aras_hayes_2022, title={A Novel Approach for Detection of Illicit Nuclear Activities Using Optically Stimulated Dosimetry}, volume={64}, number={1}, journal={ESARDA Bulletin - The International Journal of Nuclear Safeguards and Non-proliferation}, author={Aras, E.M. and Hayes, R.B.}, year={2022}, month={Jun}, pages={64–74} }
 @article{hayes_2022, title={A Standard Model Approach to Inflation}, volume={13}, ISSN={2153-1196 2153-120X}, url={http://dx.doi.org/10.4236/jmp.2022.132009}, DOI={10.4236/jmp.2022.132009}, abstractNote={By assuming the cosmological principle includes the Pauli Exclusion Principle (PEP) and that the initial singularity existed within Planck time and length scales, a model for inflationary expansion is argued using only standard model physics without any changes to general relativity.All Fermionic matter is forced by the PEP to make a quantum transition to minimally orthogonal states in sequential Planck time intervals.This results in an initial inflation effect due to nearest neighbor quantum transitions which is then exacerbated by matter and antimatter creation effects due to collisions giving rise to the observational effects of universal inflation.The model provides a mechanistic explanation for primordial expansion using only physics from the standard model, specifically utilizing the PEP as a repulsion force between indistinguishable fermions.The present theory offers the benefit of not requiring any particles or fields outside of the standard model nor utilizing changes to general relativity.More succinctly, this theory goes beyond simply offering a mathematical representation (or fit) of the functional dependence but rather offers a mechanistic model to drive inflation using only standard model physics.}, number={02}, journal={Journal of Modern Physics}, publisher={Scientific Research Publishing, Inc.}, author={Hayes, Robert Bruce}, year={2022}, pages={113–121} }
 @article{hayes_2022, title={A systems approach to a resilience assessment for agility}, volume={10}, ISSN={2164-2583}, url={http://dx.doi.org/10.1080/21642583.2022.2148138}, DOI={10.1080/21642583.2022.2148138}, abstractNote={This work proposes a theoretical approach to assessing agility in terms of a modified version of resilience during large-scale crisis to sustain operational reliability. The proposed method could be used on subsystem optimization or eventually scaled up to global interconnectedness enabling decision makers to optimize resource allocation and so obtain resilience and agility in troubling times along with long-term sustained prosperity. Introducing weights to various parameters can also allow customizing outcomes such as insuring equitable outcomes, environmental stewardship and proper response to emergencies or any national crisis. The provided mathematical formalism can then become a decision maker tool to predict corrective action outcomes from various responses to a crisis or alternatively to determine sensitivity and potential risk for a crisis from apparently ambient or slowly changing conditions. Ad-hoc examples are considered to demonstrate the generality of the approach.}, number={1}, journal={Systems Science & Control Engineering}, publisher={Informa UK Limited}, author={Hayes, Robert B.}, year={2022}, month={Dec}, pages={955–964} }
 @article{abdelrahman_hayes_2022, title={EPR Investigation of Temporal and Thermal Stability of Irradiated Sweeteners}, volume={123}, ISSN={["1538-5159"]}, DOI={10.1097/HP.0000000000001614}, abstractNote={Abstract Electron paramagnetic resonance was used to study the dosimetric properties of commercial sweeteners (sucrose, saccharin, and stevia). The results concluded that sugar has dosimetric properties of interest, which makes it suitable for dose reconstruction, emergency response, and nuclear forensics applications. The radiation dose response was investigated by irradiating samples up to 10 Gy and found to be linear. The post-irradiation stability of samples was observed to be useful for the intended applications. The results showed that the post-irradiation intensities vary from one sample to another, with the general trend demonstrating a small increase in intensities shortly after irradiation followed by an approximately constant leveling out. Finally, the effect of isochronal annealing was studied by heating samples to various temperatures. The results showed an overall stable behavior of the signal below melting temperature.}, number={6}, journal={HEALTH PHYSICS}, author={Abdelrahman, Fatma M. and Hayes, Robert B.}, year={2022}, month={Dec}, pages={476–485} }
 @article{meeks_steen_mckendee_otis_cui_volpe_hayes_agans_lewis_2022, title={Harnessing the Environment to Identify Nuclear Processes: Biologically-Mediated Approaches}, volume={24}, journal={Countering WMD Journal}, author={Meeks, H.N. and Steen, T. and McKendee, W.M. and Otis, R.P. and Cui, H.H. and Volpe, R. and Hayes, R.B. and Agans, R.T. and Lewis, A.}, year={2022}, pages={60–85} }
 @article{meeks_oates_cui_hwang_volpe_hayes_steen_agans_turick_brigmon_et al._2022, title={Harnessing the Environment to Identify Nuclear Processes: I. Biological Markers to Assess Environmental Exposure}, volume={24}, journal={Countering WMD Journal}, author={Meeks, H.N. and Oates, R.P. and Cui, H. and Hwang, G.M. and Volpe, R.P. and Hayes, R.B. and Steen, T.Y. and Agans, R.T. and Turick, C.E. and Brigmon, R. and et al.}, year={2022}, pages={93–119} }
 @article{long_hayes_2022, title={Neutron activation analysis of novel space shielding for terrestrial applications}, volume={398}, ISSN={["1872-759X"]}, DOI={10.1016/j.nucengdes.2022.111989}, abstractNote={Appropriate disposition of nuclear waste is a high priority in the production of nuclear energy and its minimization is of great interest to the public. Employing the use of metal oxide infused conformal coatings as a shielding material in a terrestrial reactor should ideally produce nuclear wastes no higher than class B while also reducing the neutron activations (and thus waste classification) of any materials behind the shield. This allows for the increased likelihood of the ability to use on-site sequestration or minimal near-surface disposal, in lieu of geological repositories, and thus the potential for considerable cost savings.}, journal={NUCLEAR ENGINEERING AND DESIGN}, author={Long, Michael and Hayes, Robert B.}, year={2022}, month={Nov} }
 @article{hayes_2022, title={Nuclear energy myths versus facts support it's expanded use - a review}, volume={2}, url={https://doi.org/10.1016/j.cles.2022.100009}, DOI={10.1016/j.cles.2022.100009}, abstractNote={In order to promote a sound basis for considering the role of nuclear in climate change, this review spans the technical topics of social and political debate surrounding nuclear energy with a focus on the objective science of these issues including nuclear waste, accidents and overall risk. Novel aspects include the emergence of nuclear energy as being potentially renewable and the antithesis of Fukushima being an argument for the unacceptable risks associated with the use of nuclear energy. The purpose of this review is to present the facts about nuclear energy divorced from political, social or comparable bias. The results argue nuclear as effectively the most attractive option from almost every possible perspective in which common social discourse would have these painted as unfavourable if not horrific.}, journal={Cleaner Energy Systems}, publisher={Elsevier BV}, author={Hayes, Robert Bruce}, year={2022}, month={Jul}, pages={100009} }
 @article{hayes_2022, title={The ubiquity of nuclear fission reactors throughout time and space}, volume={125}, ISSN={["1873-5193"]}, url={https://doi.org/10.1016/j.pce.2021.103083}, DOI={10.1016/j.pce.2021.103083}, abstractNote={The evidence for a natural uranium fission reactor in Oklo, Gabon (Africa) begs the question as to whether this was the only one to have ever occurred on earth or elsewhere. Modern nuclear terminology classifies uranium as highly enriched uranium when the U235 content exceeds 20% which is shown comparable to projecting back ca 4.5e9 yr for terrestrial uranium isotopic abundances. At that time, the natural uranium content of the earth would have been classified as highly enriched uranium. With one verified natural criticality event, more events are postulated both on earth and throughout our galaxy. The latter effect should result in some background contribution to gamma ray burst events placing nuclear reactors as an expected ubiquitous natural phenomenon throughout time and space.}, journal={PHYSICS AND CHEMISTRY OF THE EARTH}, publisher={Elsevier BV}, author={Hayes, Robert B.}, year={2022}, month={Feb} }
 @article{kanies_hayes_yang_2022, title={Thermoluminescence and optically stimulated luminescence response of Al2O3 coatings deposited by mist-chemical vapor deposition}, volume={191}, ISSN={0969-806X}, url={http://dx.doi.org/10.1016/j.radphyschem.2021.109860}, DOI={10.1016/j.radphyschem.2021.109860}, abstractNote={Aluminum oxide (Al2O3) is a widely used ceramic material which can be applied as a protective coating on metallic structures to improve corrosion resistance and mechanical properties. Al2O3 also has great potential as a functional thin film device in optoelectronics. When it is doped with carbon (Al2O3:C), this material system can serve as a reliable radiation dosimeter. The combination of optoelectronic, dosimetric, and protective properties demonstrated by Al2O3 uniquely positions it for dual use applications in nuclear forensics, nonproliferation and safeguards, emergency response, retrospective dosimetry, and nondestructive inspection. In this study, an innovative ultrasonic mist-chemical vapor deposition (Mist-CVD) system was used to deposit thin (nm level) Al2O3 coatings on 304 stainless steel substrates. The single aliquot regeneration (SAR) and additive dose reconstruction techniques were then used to investigate the thermoluminescence (TL) and optically stimulated luminescence (OSL) response of the coated substrates to increasing doses of β irradiation. This study demonstrates that nm-thick Al2O3 coatings hold promise as novel nano-dosimeters which could be leveraged for a series of applications such as nonproliferation and safeguards, retrospective dosimetry, and nondestructive inspection.}, journal={Radiation Physics and Chemistry}, publisher={Elsevier BV}, author={Kanies, Bryant and Hayes, Robert and Yang, Ge}, year={2022}, month={Feb}, pages={109860} }
 @article{hayes_2021, title={A Standard Model Neutrino Mechanism}, volume={12}, ISSN={2153-1196 2153-120X}, url={http://dx.doi.org/10.4236/jmp.2021.1211089}, DOI={10.4236/jmp.2021.1211089}, abstractNote={This work argues a new standard model physics approach for neutrino oscillations by allowing neutrinos to have their flavor be entangled amongst all interacting fermions.Specifically, for a flavor conserved system, the effects from entanglement beginning at its origin and continuing through transit can give rise to the same observational outcomes as a flavor oscillation described by mass eigenstates.The implication being that although neutrino flavor is conserved in weak processes, this is argued to hold for all subsequent interactions.In so doing, the conventional neutrino mass propagator is argued to be a dimensional artifact of the oscillation being dependent on the linear density of material along the neutrino trajectory.}, number={11}, journal={Journal of Modern Physics}, publisher={Scientific Research Publishing, Inc.}, author={Hayes, Robert B.}, year={2021}, pages={1475–1482} }
 @article{tchouaso_coon_hayes_2021, title={An effectively nondestructive method for dose assessment from accidental exposure using PCBs from electronic watches}, volume={148}, ISSN={["1879-0925"]}, DOI={10.1016/j.radmeas.2021.106648}, abstractNote={Dose assessment from accidental exposure has historically been demonstrated in cases where individuals are not wearing any personal dosimeter by measuring the luminescence signal from personal items following a radiological emergency. The limitation of using the luminescence method is that it requires extensive sample preparation, which is a challenge during emergency triage applications where rapid dose assessment is the goal. We propose a nondestructive method of dose assessment which requires minimal sample preparation and provides rapid dose estimation with potentially nondestructive assay. The nondestructive method involves collecting shavings from the printed circuit boards (PCBs) of electronic watches without altering the circuit followed by SAR measurement of the fiberglass matrix. A comparative analysis of the actual applied dose, absorbed dose from commercial OSL dosimeters, and absorbed dose from alanine dosimeters suggests that PCB shavings from electronic watches can be used as an individual dosimeter during accidental radiation exposures with some caveats.}, journal={RADIATION MEASUREMENTS}, author={Tchouaso, Modeste Tchakoua and Coon, Natalie and Hayes, Robert B.}, year={2021}, month={Nov} }
 @article{hayes_2020, title={A Novel Approach to Realistic Conservatism in Nuclear Criticality Safety Analysis}, volume={207}, ISSN={0029-5450 1943-7471}, url={http://dx.doi.org/10.1080/00295450.2020.1762472}, DOI={10.1080/00295450.2020.1762472}, abstractNote={Abstract The standard approach in nuclear criticality safety analysis is to rely quite heavily—and in some cases exclusively—on passive controls, such as assuming all worst-case conditions are by default attained. This means assumptions are made such as no poison, optimum moderation, and pure fissile actinide content at the maximum mass with optimum full reflection. What is clearly attainable is something less than any of these extremal conditions, but how can one rely on a limit based on assuming less than the worst case without some controls ensuring those assumptions are not challenged? This technical note discusses various options for approaching a defendable realistic technical basis for safety analysis by associating probabilities with conservative assumptions.}, number={3}, journal={Nuclear Technology}, publisher={Informa UK Limited}, author={Hayes, Robert B.}, year={2020}, month={Jul}, pages={460–467} }
 @article{devanzo_hayes_2020, title={Ionizing Radiation Shielding Properties of Metal Oxide Impregnated Conformal Coatings}, volume={171}, ISSN={["1879-0895"]}, DOI={10.1016/j.radphyschem.2020.108685}, abstractNote={Conformal coatings provide environmental protection for sensitive military electronics. Preliminary MCNP6® modeling of metal oxide impregnated acrylic conformal coatings indicates a factor of 300 reduction in gammas below 10 keV and up to a 225% reduction in neutron displacement damage to Si-based electronics across the Watt spectrum. This work provides data which can allow an optimal overall shielding worth per total mass to be evaluated.}, journal={Radiation Physics and Chemistry}, author={DeVanzo, M. and Hayes, R.B.}, year={2020}, month={Jul}, pages={108685} }
 @article{hayes_abdelrahman_2020, title={Low level EPR dosimetry of a commercial sugar}, volume={157}, ISSN={0969-8043}, url={http://dx.doi.org/10.1016/j.apradiso.2020.109038}, DOI={10.1016/j.apradiso.2020.109038}, abstractNote={This work demonstrated the combined utility of empty tube subtraction, over-modulation, native signal subtraction and spectral filtration in low level dosimetry using commercial sugar samples. The native signal component was found to have an effective peak to peak equivalent of 150 mGy. If the zero dose native signal is accurately modeled and subtracted, the detection limit was estimated to be 0.2 Gy although intercept uncertainties were as low as 25 mGy. This was enabled by resultant slope uncertainties as low as 3% with residual variations of approximately 0.1 Gy.}, journal={Applied Radiation and Isotopes}, publisher={Elsevier BV}, author={Hayes, R.B. and Abdelrahman, F.M.}, year={2020}, month={Mar}, pages={109038} }
 @article{hayes_cope_2020, title={Opportunities for a graded approach in air sample assay and triage}, volume={60}, journal={ESARDA Bulletin}, author={Hayes, R.B. and Cope, S.J.}, year={2020}, month={Jun}, pages={43–52} }
 @article{hayes_o'mara_2020, title={Retrospective characterization of special nuclear material in time and space}, volume={133}, url={https://doi.org/10.1016/j.radmeas.2020.106301}, DOI={10.1016/j.radmeas.2020.106301}, abstractNote={A 4.5 kg sphere of α-phase plutonium was subjected to passive imaging using optically stimulated luminescence dosimetry techniques via inverse square modeling under cylindrical symmetry around the dosimeter array. The results showed angular resolution in the localization capability close to 1° due to axial resolution below 1 cm. Radial resolution was much worse having an offset of 16 cm using only point source geometry estimates for the commercial dosimeters. Using MCNP™ to reconstruct the profile demonstrated a substantial improvement in reconstructing the relative response as opposed to assuming simple point source geometry. From this, an inverse solving approach known as DRAM was used to estimate source distribution in addition to location. These results are considered regarding their implications for nuclear nonproliferation to the extent they demonstrate potential to determine whether illicit nuclear material had historically been kept in any specific location or alternatively, whether such materials had not been kept in a location they were claimed to have been stored. Having measured the materials location and knowing the integrated measurement time then allows estimating amount of material via dose (or alternatively, knowing the assay could give storage time estimates).}, journal={Radiation Measurements}, publisher={Elsevier BV}, author={Hayes, R.B. and O'Mara, R.P.}, year={2020}, month={Apr}, pages={106301} }
 @article{o’mara_hayes_2020, title={Three-dimensional positional analysis of weapons grade plutonium using gridded arrays of dosimeters}, volume={61}, journal={ESARDA Bulletin}, author={O’Mara, R.P. and Hayes, R.B.}, year={2020}, month={Dec} }
 @article{hayes_2020, title={Unaccounted for uncertainties in radioaerosol assays as used in plume reconstruction or treaty verification}, volume={60}, journal={ESARDA Bulletin}, author={Hayes, R.B.}, year={2020}, month={Jun}, pages={53–59} }
 @article{cope_hayes_2019, title={Incremental Gains in Transuranic Activity Analysis in Air Samples for Radiological Emergency Response}, volume={205}, ISSN={0029-5450 1943-7471}, url={http://dx.doi.org/10.1080/00295450.2019.1590074}, DOI={10.1080/00295450.2019.1590074}, abstractNote={Abstract The alpha activity discrimination problem between radon progeny and transuranic (TRU) isotopes is evaluated at the times relevant for radiological emergency response using temporal decay properties. This study evaluates various effects from naturally occurring radon progeny creating alpha spectral overlap with the TRU region of interest. The methodology helps to address the potential masking of a radiological threat at worst or, at best, inhibiting response efforts due to delays caused by high levels of radon progeny. This work seeks to provide a rapid, conservative TRU estimation method in as little as 30 min. Surrogate TRU activity is introduced to the assays via check sources as a validation test for discrimination against varied levels of radon progeny collected on environmental air samples. A 2-h activity decay profile counting window was sectioned into multiple combinations of 30-min increments to investigate optimal counting segments and to simulate potential field-collection scenarios with limited resource availability. The experiment sought to discriminate low levels of introduced TRU activity comparable to the natural background on each sampled filter. Using this approach, the study confirmed the utility of the estimation methodology in as little as 30 min. Additional measurement time taken in the decay profile demonstrated marked improvements in both accuracy and precision of the TRU activity estimate as expected. Studies on the potential functional dependence of fitting parameters that influence the TRU estimate and associated uncertainty may improve further model development. The methodology is flexible to accommodate any gross alpha/beta scalar counter and is designed to be implemented within a graded approach based on time and resource availability present in the response. The estimation framework enables rapid air assay with a proper technical basis in times not currently realized in radiological emergency response.}, number={9}, journal={Nuclear Technology}, publisher={Informa UK Limited}, author={Cope, S. Joseph and Hayes, Robert B.}, year={2019}, month={Apr}, pages={1219–1235} }
 @article{hayes_o’mara_hooper_2019, title={Initial TL/OSL/EPR Considerations for commercial diatomaceous earth in retrospective dosimetry and dating}, volume={1-10}, ISSN={0144-8420 1742-3406}, url={http://dx.doi.org/10.1093/rpd/ncz013}, DOI={10.1093/rpd/ncz013}, abstractNote={Diatomaceous earth is found in various locations around the planet. It is caused by the deposited exoskeleton material formed by the death of large concentrated populations of diatoms. The exoskeleton is effectively pure silicate and as such becomes a prospective material for retrospective dosimetry and dating. This work investigated the thermoluminescence (TL) and optically stimulated luminescence properties of commercially obtained diatomaceous earth. The material was not found to have useful dosimetric properties with conventional TL methodologies but did provide large dose estimates using the Single Aliquot Regeneration technique on some subset samples. These findings for organic silicate did suggest some mechanisms explaining the sensitization process in geological silicate materials utilized in dosimetry and dating. Electron paramagnetic resonance was identified as a potential future method for evaluating this material as it revealed unique signal components not found in igneous or commercially produced silicates.}, journal={Radiation Protection Dosimetry}, publisher={Oxford University Press (OUP)}, author={Hayes, Robert B and O’Mara, Ryan P and Hooper, David A}, year={2019}, month={Feb} }
 @article{hayes_o'mara_abdelrahman_2019, title={Nuclear forensics via the electronic properties of particulate and samples}, volume={59}, journal={ESARDA Bulletin}, author={Hayes, R.B. and O'Mara, R.P. and Abdelrahman, F.}, year={2019}, month={Dec}, pages={21–28} }
 @inproceedings{hayes_o’mara_abdelrahman_2019, title={Opportunities for a graded approach in air sample assay and triage}, ISBN={978-92-76-08679-6}, DOI={10.2760/159550}, booktitle={41st ESARDA Annual Meeting symposium on safeguards and nuclear material management}, author={Hayes, RB and O’Mara, RP and Abdelrahman, F}, year={2019} }
 @article{hayes_o'mara_2019, title={Retrospective dosimetry at the natural background level with commercial surface mount resistors}, volume={121}, ISSN={1350-4487}, url={http://dx.doi.org/10.1016/j.radmeas.2018.12.007}, DOI={10.1016/j.radmeas.2018.12.007}, abstractNote={A single aliquot regenerative (SAR) protocol utilizing thermoluminescence demonstrated precise and accurate retrospective dosimetry capability using common commercial surface mount resistors at levels able to discriminate the age of resistors based on background dose accrual. Detection limits below 10 mGy can be realized with this method having precision at the 1 Gy level in the range of only 3% which is substantially better than that required for emergency response dosimetry. Moreover, these dose estimates could be obtained in mere hours rather than current biodosimetry methods which can take weeks.}, journal={Radiation Measurements}, publisher={Elsevier BV}, author={Hayes, Robert B. and O'Mara, Ryan P.}, year={2019}, month={Feb}, pages={42–48} }
 @article{hayes_2019, title={Retrospective uranium enrichment potential using solid state dosimetry techniques on ubiquitous building materials}, volume={47}, number={2}, journal={Journal of Nuclear Material Management}, author={Hayes, R.B.}, year={2019}, pages={4–12} }
 @article{cope_hayes_2019, title={Validation of a rapid, conservative transuranic alpha activity estimation method in air samples}, volume={39}, ISSN={0952-4746 1361-6498}, url={http://dx.doi.org/10.1088/1361-6498/ab1bfd}, DOI={10.1088/1361-6498/ab1bfd}, abstractNote={In air filter assay for radiological emergency response, radon (222Rn) and thoron (220Rn) progeny are known interferents to transuranic activity estimation. Previous work detailed a conservative, graded approach for TRU alpha activity estimation from air samples void of transuranic activity yet containing varying amounts of radon and thoron progeny. Validation of this method to produce rapid, conservative and defensible transuranic alpha activity estimates was accomplished through introduction of surrogate transuranic activity, 239Pu and 230Th check sources, along with the naturally occurring radioactive progeny from an environmental air filter. Following air collection, the filter was centre hole-punched with the transuranic check source placed underneath the filter during counting. With the surrogate transuranic activity introduced into the measurement, verification of the previously studied methodology for rapid transuranic activity estimation was determined with quantifiable conservative bias. 70 environmental filters with various levels of radon progeny and air sampling duration were collected; 35 examined with the 239Pu check source and 35 studied with the 230Th check source. To characterise the expected transuranic activity introduced to the counting experiment without the environmental interferents of radon and thoron progeny, 30 blank filters were counted using the described experimental setup with each of the respective surrogate sources. Following characterisation of the sources with blank filters, transuranic activity estimation comparison against the 70 environmental filters with natural background radioactive progeny interferents was accomplished. This work contributes to the comprehensive analysis of operational air samples by detailing validation results for a rapid and conservative transuranic alpha activity estimation methodology.}, number={3}, journal={Journal of Radiological Protection}, publisher={IOP Publishing}, author={Cope, S Joseph and Hayes, Robert B}, year={2019}, month={Jun}, pages={749–765} }
 @misc{libraries_2018, title={American National Standard Instrumentation and Systems for Monitoring Airborne Radioactivity}, ISBN={9781504447973}, url={http://dx.doi.org/10.1109/ieeestd.2018.8337857}, DOI={10.1109/ieeestd.2018.8337857}, publisher={IEEE}, author={Libraries, NC State University}, year={2018}, month={Apr} }
 @article{o'mara_hayes_2018, title={Dose Deposition Profiles in Untreated Brick Material}, volume={114}, ISSN={["1538-5159"]}, DOI={10.1097/hp.0000000000000843}, abstractNote={Abstract In nuclear forensics or accident dosimetry, building materials such as bricks can be used to retrospectively determine radiation fields using thermoluminescence and/or optically stimulated luminescence. A major problem with brick material is that significant chemical processing is generally necessary to isolate the quartz from the brick. In this study, a simplified treatment process has been tested in an effort to lessen the processing burden for retrospective dosimetry studies. It was found that by using thermoluminescence responses, the dose deposition profile of a brick sample could be reconstructed without any chemical treatment. This method was tested by estimating the gamma-ray energies of an 241Am source from the dose deposition in a brick. The results demonstrated the ability to retrospectively measure the source energy with an overall energy resolution of approximately 6 keV. This technique has the potential to greatly expedite dose reconstructions in the wake of nuclear accidents or for any related application where doses of interest are large compared to overall process system noise.}, number={4}, journal={HEALTH PHYSICS}, author={O'Mara, Ryan and Hayes, Robert}, year={2018}, month={Apr}, pages={414–420} }
 @inproceedings{o’mara_hayes_2018, title={Grain size and density separation effects on luminescence dose estimates using brick material}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85067121319&partnerID=MN8TOARS}, booktitle={Embedded Topical Meeting - Advances in Nuclear Nonproliferation Technology and Policy Conference 2018, ANTPC 2018}, author={O’Mara, R.P. and Hayes, R.B.}, year={2018}, pages={192–195} }
 @misc{hayes_2018, title={LNT May Be Lethal but ALARA Is Inherently Useful}, volume={115}, ISSN={["1538-5159"]}, DOI={10.1097/hp.0000000000000923}, abstractNote={Dear Editors: I DID VERY much enjoy reading the article by Feinendegen and Cuttler (2018). Although they did present their facts correctly and succinctly, I would like to offer an alternative, if not supplemental, perspective on their work. They mentioned the fear from genetic changes at nominal doses but only addressed radiogenic carcinomas. A related topic of fear not evaluated is that of radiogenic mutations from a parent that are passed on to progeny. As far as this concerns Homo sapiens, the literature has shown no measured traits are observable (NRC 2006). That some animals have demonstrated weak tendencies to incur genetic mutations (Ryabokon and Goncharova 2006) suggests that if it could occur in humans, it would be above the lethal dose, explaining why it has not been seen in children of the atomic bomb survivors (Neel and Schull 1991). Given the levels of radiophobia in developed countries even at small dose levels (Myslobodsky 2001), it is worthwhile to point out on this topic that the literature demonstrates how carcinomas have been with us almost from the beginning of modern animal life insofar as they are found in dinosaur bones, indicating it is an ancient disease common to life on this planet (Capasso 2004; Dunn 2012; Vincent 2010). The authors pointed out the dangers from radiophobia but did not elucidate how this is such a drastic departure from their recognition of no medical effects being observed at low and nominal doses as there are clearly acutely severe psychosocial and psychosomatic effects. As an example, in stark contrast to both the World Health Organization (WHO) and United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) findings that no measurable radiogenic medical effects are expected to the public from the entire Fukushima release (WHO 2013; UNSCEAR 2013, 2015), the evacuation of populations has alone resulted in over 2,000 deaths (Hayakawa 2016) in addition to the host of substantial documented radiophobic medical conditions such as increases in being overweight, hypertension, and diabetes (Hasegawa et al. 2016). In addition to these, the literature is clear that the psychosocial effects from radiophobia have resulted in substantial increases in suicides in populations exposed to small anthropogenic accidental doses (Rahu et al. 2015). The conclusion is stark and overwhelming that radiophobia is altogether lethal, having taken many thousands of victims already. In this sense, the promotion of radiophobia could verywell be unethical if not immoral. Given that discrimination of the facts in this case results literally in life or death for so many individuals, it is difficult to overstate its importance and hence is the basis for this letter. My comments above do not necessarily contradict the authors’ but rather are intended to highlight details not addressed in their work. Still, as a former as low as reasonably achievable (ALARA) program coordinator myself, I would like to offer another alternate perspective on the utility of the linear no-threshold (LNT) theory in the industry (only as far as ALARA is concerned). I have heard many in our industry criticize ALARA as being an outcome of LNT itself. This may be true in some sense, but the utility of a rigorous ALARA program should not be overlooked as we shed the LNT model for more empirical and accurate risk paradigms. It would be negligent not to monitor nuclear operations with at least the same rigor as any other industrial endeavor to implement continual improvement and quality control. A few representative indicators unique to a nuclear facility include worker dose, off-site releases, contamination events and their extent, etc. There are certainly many more indicators that could be trended to assess the operator’s ability to control radioactivity and so evaluate potential opportunities for improvement. In a very legitimate sense, this is really all an effective ALARA program is: a quality control tool when properly handled by a competent health physicist. Safety issues are, by definition, separate from ALARA (which would be addressed through the unreviewed safety question process) and so ALARA should not address safety, even in its current form. If LNT is updated with more accurate models, ALARA might change both its name and limits, but the process and workings should still be present. Thiswould serve tomaintain the highest level of quality in operations and throughput. Without this, radiological operations would literally be out of control in a statistical sense. The same considerations apply to facility free-release limits. The current regulatory limits assume that a member of the public can be exposed to multiple free-release vectors in any given year. Whether this is from transportation, medical patients, hospitals, nuclear facilities, well logging, or other industrial radiography operations, all such doses are cumulative. Increased limits would be appropriate, but even}, number={3}, journal={HEALTH PHYSICS}, author={Hayes, Robert Bruce}, year={2018}, month={Sep}, pages={391–392} }
 @article{cope_hayes_2018, title={Preliminary work toward a transuranic activity estimation method for rapid discrimination of anthropogenic from TRU in alpha air samples}, volume={114}, number={4}, journal={Health Physics (New York, N.Y.)}, author={Cope, S.J. and Hayes, R.B.}, year={2018}, pages={319–327} }
 @article{duckic_hayes_2018, title={Total Ambient Dose Equivalent Buildup Factors for Portland Concrete}, volume={115}, ISSN={["1538-5159"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85051229047&partnerID=MN8TOARS}, DOI={10.1097/HP.0000000000000879}, abstractNote={Abstract In this work, total ambient dose equivalent buildup factors for Portland concrete slabs are calculated using Monte Carlo n-particle software MCNP6™. Buildup factor calculations could approach intractable solutions in general as they depend on a large number of variables. These include geometry, source energy, and the composition of the shield (which itself can be heterogeneous). In this work, 252Cf and americium-beryllium sources are considered, as well as monoenergetic incident neutrons in the energy range from 0.025 eV to 14 MeV at multiple incident angles. The shielding material of interest was taken to be standard Portland concrete. The transmitted neutron and gamma-ray ambient dose rate was calculated first and then used for total buildup factor calculations. Perhaps more telling than the calculated theoretical buildup factor, the credible dispersion in expected resultant buildup factors was also calculated by conducting a very rudimentary sensitivity analysis, varying the water content in the first case and then varying the amount of aggregate. An additional aim of this work is to provide a model based on the machine-learning technique called the support vector regression method in the calculation of concrete buildup factors.}, number={3}, journal={HEALTH PHYSICS}, author={Duckic, Paulina and Hayes, Robert Bruce}, year={2018}, month={Sep}, pages={324–337} }
 @article{duckic_hayes_2018, title={Total ambient dose equivalent buildup factor determination for NBS04 concrete}, volume={114}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85046799955&partnerID=MN8TOARS}, DOI={10.1097/HP.0000000000000834}, abstractNote={Abstract Buildup factors are dimensionless multiplicative factors required by the point kernel method to account for scattered radiation through a shielding material. The accuracy of the point kernel method is strongly affected by the correspondence of analyzed parameters to experimental configurations, which is attempted to be simplified here. The point kernel method has not been found to have widespread practical use for neutron shielding calculations due to the complex neutron transport behavior through shielding materials (i.e. the variety of interaction mechanisms that neutrons may undergo while traversing the shield) as well as non-linear neutron total cross section energy dependence. In this work, total ambient dose buildup factors for NBS04 concrete are calculated in terms of neutron and secondary gamma ray transmission factors. The neutron and secondary gamma ray transmission factors are calculated using MCNP6™ code with updated cross sections. Both transmission factors and buildup factors are given in a tabulated form. Practical use of neutron transmission and buildup factors warrants rigorously calculated results with all associated uncertainties. In this work, sensitivity analysis of neutron transmission factors and total buildup factors with varying water content has been conducted. The analysis showed significant impact of varying water content in concrete on both neutron transmission factors and total buildup factors. Finally, support vector regression, a machine learning technique, has been engaged to make a model based on the calculated data for calculation of the buildup factors. The developed model can predict most of the data with 20% relative error.}, number={6}, journal={Health Physics}, author={Duckic, P. and Hayes, R.B.}, year={2018}, pages={569–581} }
 @article{hayes_2017, title={A standard model approach to dark energy and inflation}, volume={26}, url={http://journalofcosmology.com/JOC26/Hayes.pdf}, journal={Journal of Cosmology}, author={Hayes, R.B.}, year={2017}, month={Jun}, pages={14850–14859} }
 @inbook{hayes_2017, title={Applications of Radioisotopes}, ISBN={9781493924936}, DOI={10.1007/978-1-4939-2493-6_952-1}, booktitle={Encyclopedia of Sustainability Science and Technology}, publisher={New York: Springer}, author={Hayes, R. B.}, year={2017} }
 @article{hayes_2017, title={RECONSTRUCTION OFA RADIOLOGICAL RELEASE USING AEROSOL SAMPLING}, volume={112}, ISSN={["1538-5159"]}, DOI={10.1097/hp.0000000000000645}, abstractNote={Abstract Reconstructing a radiological release using offsite air sampling is considered using measurements from the WIPP site event. Demonstration of the capabilities is shown using the HotSpot code as an example of the approach in general. The results show the empirical steps that could be folded into an iterative approach to back extrapolation of a radiological release from a nuclear facility. It is shown here that the limiting factor in detection is not counting statistics of the activity but rather the statistics for aerosols having small sample population numbers due to the lognormal distribution of particle radii.}, number={4}, journal={HEALTH PHYSICS}, author={Hayes, Robert Bruce}, year={2017}, month={Apr}, pages={326–337} }
 @article{hayes_sholom_2017, title={RETROSPECTIVE IMAGING AND CHARACTERIZATION OF NUCLEAR MATERIAL}, volume={113}, ISSN={["1538-5159"]}, DOI={10.1097/hp.0000000000000680}, abstractNote={Abstract Modern techniques for detection of covert nuclear material requires some combination of real time measurement and/or sampling of the material. More common is real time measurement of the ionizing emission caused by radioactive decay or through the materials measured in response to external interrogation radiation. One can expose the suspect material with various radiation types, including high energy photons such as x rays or with larger particles such as neutrons and muons, to obtain images or measure nuclear reactions induced in the material. Stand-off detection using imaging modalities similar to those in the medical field can be accomplished, or simple collimated detectors can be used to localize radioactive materials. In all such cases, the common feature is that some or all of the nuclear materials have to be present for the measurement, which makes sense; as one might ask, “How you can measure something that is not there?” The current work and results show how to do exactly that: characterize nuclear materials after they have been removed from an area leaving no chemical trace. This new approach is demonstrated to be fully capable of providing both previous source spatial distribution and emission energy grouping. The technique uses magnetic resonance for organic insulators and/or luminescence techniques on ubiquitous refractory materials similar in theory to the way the nuclear industry carries out worker personnel dosimetry. Spatial information is obtained by acquiring gridded samples for dosimetric measurements, while energy information comes through dose depth profile results that are functions of the incident radiation energies.}, number={2}, journal={HEALTH PHYSICS}, author={Hayes, Robert B. and Sholom, Sergey}, year={2017}, month={Aug}, pages={91–101} }
 @article{hayes_2017, title={Some Mathematical and Geophysical Considerations in Radioisotope Dating Applications}, volume={197}, ISSN={["1943-7471"]}, DOI={10.13182/nt16-98}, abstractNote={Some quality considerations for use in isotopic dating are presented to identify and correct heretofore unidentified overestimate scenarios. These include to a lesser degree the statistical interpretation issues with linear-least-squares fitting results but more importantly the isotope effect in the individual components of the isochron coefficient ratios. By taking into consideration the isotope effect (differential mass diffusion rates) when measuring isotopic ratios from very old samples, the distribution dependency in the coefficient ratios will cause a bias if isotopic diffusion rates are not identical throughout a sample. The isotope effect is that isotopes having a smaller atomic mass will diffuse faster throughout a medium than will their heavier counterparts causing concentration gradients of their ratios even when there are no contributions from radioactive decay. The application to Rb/Sr dating is evaluated and shown to result in expected age overestimates when isotopic ratios are employed to linearize the isochron. A suggested method to test for this effect is argued to require rigorous statistical analysis. An associated optimal sampling technique would involve using single-grain etching. It is also shown that the only method to fully eliminate the isotope effect is to not use isotopic ratios at all in radioisotopic dating as the physics do not require the use of isotopic ratios for geochronological dating. However, without the ratios, the data are inherently noisy.}, number={2}, journal={NUCLEAR TECHNOLOGY}, author={Hayes, Robert B.}, year={2017}, month={Feb}, pages={209–218} }
 @article{hayes_2016, title={CONSEQUENCE ASSESSMENT OF THE WIPP RADIOLOGICAL RELEASE FROM FEBRUARY 2014}, volume={110}, ISSN={["1538-5159"]}, DOI={10.1097/hp.0000000000000477}, abstractNote={AbstractOn 14 February 2014, a continuous air monitor (CAM) alarm at the exit of panel 7 in the Waste Isolation Pilot Plant (WIPP) underground facility caused the mine ventilation to shift from unfiltered air over to HEPA filtration for its effluent. Subsequent measurements of the effluent at both pre- and post-HEPA filtration using representative sampling demonstrated that a release had occurred. Using modeling based on measured effluent activity, onsite dose estimates were calculated and later measured via bioassay to be less than 0,1 mSv from intakes of radioactivity. The maximum offsite dose potential to nearby dwellings was modeled to be 1 µSv or less, which was consistent with air samples being taken at those dwellings during the release, demonstrating impressive accuracy and precision. No worker or public dose limits have been exceeded, and the release was substantially below the annual release limits for the WIPP site.}, number={4}, journal={HEALTH PHYSICS}, author={Hayes, Robert Bruce}, year={2016}, month={Apr}, pages={342–360} }
 @article{milvenan_hayes_2016, title={Contributions of Various Radiological Sources to Background in a Suburban Environment}, volume={111}, ISSN={["1538-5159"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84991228575&partnerID=MN8TOARS}, DOI={10.1097/hp.0000000000000564}, abstractNote={AbstractThis work is a brief overview and comparison of dose rates stemming from both indoor and outdoor natural background radiation and household objects within a suburban environment in North Carolina. Combined gamma and beta dose rates were taken from indoor objects that ranged from the potassium in fruit to the americium in smoke detectors. For outdoor measurements, various height and time data samples were collected to show fluctuations in dose rate due to temperature inversion and geometric attenuation. Although each sample tested proved to have a statistically significant increase over background using Students t-test, no sample proved to be more than a minor increase in natural radiation dose. The relative contributions from natural radioactivity such as potassium in foods and common household items are shown to be easily distinguished from background using standard handheld instrumentation when applied in a systematic, methodological manner.}, number={5}, journal={HEALTH PHYSICS}, author={Milvenan, Richard D. and Hayes, Robert B.}, year={2016}, month={Nov}, pages={S193–S199} }
 @article{hayes_2016, title={IMPLEMENTATION OF A PORTABLE HPGE FOR FIELD CONTAMINATION ASSAY}, volume={110}, ISSN={["1538-5159"]}, DOI={10.1097/hp.0000000000000501}, abstractNote={AbstractUsing MCNP to construct a detector model based initially on x-ray images of a portable high purity germanium (HPGe) detector followed by normalizing covering material values to also agree with check source responses, a validation of the model was attained. By calibrating the detector parameters using large count spectra, rigorous reproducibility is attained for high activity measurements but does not prevent deviations from normality in error distributions at the very low count events where spectral peaks are not always identifiable. The resulting model was created to allow operational assay of contamination over large areal distributions that could not otherwise be measured, such as the exhaust shaft at the Waste Isolation Pilot Plant (WIPP). Results indicate that contamination levels of activity in the exhaust shaft can be assayed to within a factor of 2. Detection limits are evaluated to be well below the contamination levels, which would constitute a legal environmental release if unfiltered ventilation of the underground facility were used.}, number={6}, journal={HEALTH PHYSICS}, author={Hayes, Robert Bruce}, year={2016}, month={Jun}, pages={571–579} }
 @article{hayes_2015, title={Operational Check Source Recalibration}, volume={109}, DOI={10.1097/hp.0000000000000309}, abstractNote={AbstractA formal protocol whereby a segregated source is used for later quality control trending and recalibration of operational sources is described. The method is of potential use for any quality radioactive assay program where multiple sources may be in use such that long term loss in activity is possible and not readily detected and corrected using common statistical assessment criteria. The method relies upon a rigorous initial characterization effort that can later be credited to minimize error propagation during recalibration to monitor the overall uncertainty budget. A simple example attachment for use in written procedures is also provided.}, journal={Health Physics}, publisher={Ovid Technologies (Wolters Kluwer Health)}, author={Hayes, Robert B.}, year={2015}, pages={S156–S161} }
 @article{hayes_akbarzadeh_2014, title={Using Isotopic Ratios for Discrimination of Environmental Anthropogenic Radioactivity}, volume={107}, DOI={10.1097/hp.0000000000000116}, abstractNote={AbstractWhen air is pulled into the WIPP repository for ventilation purposes, this air is unfiltered and contains all the components of ubiquitous anthropogenic radionuclides from global nuclear fallout (including 137Cs and Pu isotopes). Although the NORM in aeolian sand and dust contribute to the gross alpha beta activity on effluent air filters, there remains a need to discriminate effluent TRU generated in the disposal process at WIPP from TRU being pulled into the repository with the unfiltered surface air. This is only evaluated using ratios of Cs and Pu activity found through radioassay of air filters taken from the mine effluent. By characterizing both the credible range of 137Cs/239,240Pu ratios from the environment and those known to exist in the waste, a rigorous test criteria is attained. The use of HPGE to assay 137Cs in the intake dust plated out in the mine allowed a gross assay of total TRU radioactivity pulled into the mine over time from global fallout. Radiochemistry of samples from deposition in the mine’s air intake shaft was also carried out. The use of net activity ratios at background levels is also shown to follow a Cauchy distribution in terms of their expected statistical distributions.}, number={4}, journal={Health Physics}, publisher={Ovid Technologies (Wolters Kluwer Health)}, author={Hayes, Robert B. and Akbarzadeh, Mansour}, year={2014}, pages={277–291} }
 @article{hayes_2013, title={Nuclear criticality as a contributor to gamma ray burst events}, volume={345}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84875523898&partnerID=MN8TOARS}, DOI={10.1007/s10509-013-1371-z}, abstractNote={Most gamma ray bursts are able to be explained using supernovae related phenomenon. Some measured results still lack compelling explanations and a contributory cause from nuclear criticality is proposed. This is shown to have general properties consistent with various known gamma ray burst properties. The galactic origin of fast rise exponential decay gamma ray bursts is considered a strong candidate for these types of events.}, number={1}, journal={Astrophys Space Sci}, publisher={Springer Science \mathplus Business Media}, author={Hayes, Robert B.}, year={2013}, month={Jan}, pages={147–154} }
 @book{hayes_2013, title={Nuclear science and technology made so simple, it belongs in your newspaper – popular science topics for the layman}, url={https://www.amazon.com/Nuclear-Science-Technology-belongs-newspaper-ebook/dp/B00CC2KB5S}, publisher={Amazon/Robert B. Hayes}, author={Hayes, RB}, year={2013}, month={Apr} }
 @article{hayes_2011, title={Special issue on the 16th biennial topical meeting of the radiation protection and shielding division}, volume={175}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79960675149&partnerID=MN8TOARS}, DOI={10.13182/NT11-A12259}, abstractNote={This issue of Nuclear Technology features selected papers from the 16th Biennial Topical Meeting of the American Nuclear Society ~ANS! Radiation Protection and Shielding Division ~RPSD! held in Las Vegas, Nevada, in April 2010 ~RPSD2010!. The general conference chair was Anthony Hechanova from the University of Nevada, Las Vegas ~UNLV!, and the technical program chair was Robert B. Hayes from the Waste Isolation Pilot Plant ~WIPP! in Carlsbad, New Mexico. Generous support in many ways was given to RPSD2010 by UNLV. Additional support was provided by the Remote Sensing Laboratory, Varian Medical Systems, Inc., WIPP, Rad-Ware Inc., and of course the entire local section of ANS. Special individual efforts by Steven Curtis, David Stahl, and Dixie O’Dou were of great support and are duly acknowledged. RPSD2010 had 205 registrants from 18 countries, but only 170 attendees were at the meeting— mainly due to the eruption of Iceland’s volcano interfering with air travel. The conference included 157 presentations and offered 6 tutorials. The RPSD was pleased to present its prestigious Rockwell Lifetime Achievement Award to Nicholas Tsoulfanidis, Professor Emeritus of nuclear engineering and Editor of Nuclear Technology, for his numerous accomplishments in the radiation sciences. The RPSD topical meetings focus on all shielding-related applications. Those applications in this topical included medical physics, radiation protection, shielding, detector physics and design, neutron physics, Monte Carlo calculations, radiation transport calculations, and radiation detection and measurement. A special track for activities at UNLV was also included that covered radiochemistry and nuclear forensics The papers presented at this conference contained the latest research and information on the topics of radiation shielding, radiation detection, and medical applications of radiation. To give a presentation at the conference, attendees were required to submit an abstract of less than two pages in length. The abstract was then peer reviewed by two independent experts, with options given to authors for revisions based on the referee recommendations. Accepted papers were then presented at the conference. After the meeting, authors were invited to submit their papers for publication in Nuclear Technology. An additional review of the submitted papers was performed by two reviewers chosen by the Editor, in accordance with Nuclear Technology’s normal peer-review process. Because of the in-depth review process, which has ensured high-quality papers, and the important topics that are discussed, we hope that this special issue will be a valuable reference for nuclear scientists and engineers.}, number={1}, journal={Nuclear Technology}, author={Hayes, R.B.}, year={2011}, pages={1} }
 @article{hayes_2010, title={Emergency Situation Air Sampling}, DOI={10.1201/b10261-22}, journal={Radioactive Air Sampling Methods}, publisher={Informa UK Limited}, author={Hayes, Robert}, year={2010}, month={Oct}, pages={357–367} }
 @misc{maiello_hoover_2010, title={Radioactive Air Sampling Methods}, ISBN={9780429126932}, url={http://dx.doi.org/10.1201/b10261}, DOI={10.1201/b10261}, abstractNote={Objectives, Safety Issues, Standards, and a Life-Cycle Approach for Sampling Airborne Radioactivity Objectives for Sampling Airborne Radioactivity, M.D. Hoover, G.J. Newton, and M.L. Maiello Radiation Safety Issues for Air Sampling, M.L. Maiello and M.D. Hoover Standards, Guidelines, Regulations, and Recommendations for Measuring Airborne Radioactivity, M.D. Hoover, M. Cox, C.G. Jones, L. Grivaud, M.L. Johnson, M.L. Maiello, and G.J. Newton A Life-Cycle Approach to Development and Application of Air Sampling Methods and Instrumentation, M.D. Hoover and M. Cox Fundamentals of Radioactivity and Radioactive Aerosols Review of Radioactivity, Detection, and Measurement, M.L. Maiello The Physics of Aerosols, E. Sajo Behavior of Radioactive Aerosols and Gases, M.D. Hoover Filtration, M.D. Hoover Behavior of Radon and its Decay Products, P. Jenkins Internal Dosimetry of Inhaled Radioactive Aerosols, C.A. Potter Fundamentals of Sampling System Design and Operation for Airborne Radioactivity Basic Air Sampling Equipment, M.L. Maiello Calibration of Air Samplers and Monitors, J.T. Voss and J.J. Whicker Appendix A: Generic Calibration Procedure, J.T. Voss and J.J. Whicker Appendix B: A Multiple-Frame-of-Reference Method for Rotameter Correction Factors, M.D. Hoover Principles of Air Sampler Placement in the Workplace, J.J. Whicker The Practice of Continuous Air Monitoring for Alpha-Emitting Radionuclides, J.C. Rodgers Principles of Sampling Airborne Radioactivity from Stacks, J. Glissmeyer Methods for Comprehensive Characterization of Radioactive Aerosols: A Graded Approach, M.D. Hoover Nonroutine Radioactive Air Sampling Emergency Situation Air Sampling, R.B. Hayes Appendix: First Responder Radiological Monitoring, T.F. O'Connell and S.P. Clendenin Monitoring Nuclear Fallout, H.L. Beck Example Air Sampling Methods for Airborne Radioactivity Introduction to the Methods, M.L. Maiello and M.D. Hoover Method 1: Determination of the Gross Alpha-Radioactivity Content of the Atmosphere Method 2: Determination of the Gross Beta-Radioactivity Content of the Atmosphere Method 3: Determination of the Tritiated Water Vapor Content of the Atmosphere Method 4: Determination of the Elemental Tritium Content of the Atmosphere Method 5: Determination of Carbon-14 in Air Method 6: Determination of the Iodine-131 Content of the Atmosphere Method 7: Sampling Air for Argon-41, Krypton-85, and Other Gamma-Emitting Radioactive Gases Using Gamma-Spectroscopy Method 8: Determination of the 222Rn Content of the Atmosphere Method 9: A Procedure for Continuous Air Monitoring of Plutonium Method 10: Personal Air Sampling for Particulate Radioactivity Method 11: Real-Time Breathing Zone Monitoring for Personal Respiratory Protection Glossary, M.L. Maiello and M. Cox Appendix: Radionuclide Characteristics, M.L. Maiello Index}, publisher={CRC Press}, year={2010}, month={Oct} }
 @article{hayes_2009, title={Continuous Air Monitor Algorithm Development}, volume={168}, ISSN={0029-5450 1943-7471}, url={http://dx.doi.org/10.13182/nt09-a9097}, DOI={10.13182/nt09-a9097}, abstractNote={Abstract This paper describes an algorithm intended for use in the U.S. Navy’s next-generation air particle detector designed for measuring 60Co air contamination. The algorithm measures both alpha and beta activity from an air filter utilizing passivated implanted planar silicon detectors for spectrometry of both particle types and is designed to compensate for radon progeny to discriminate this from the beta emissions of 60Co. This is done by correlating the specific alpha emissions with their beta emission parents, or their beta emission progeny, as appropriate. In addition, the algorithm is unique in that by using region of interest (ROI) windows, it is less sensitive to spectral smearing due to dust or humidity effects on the particle depositions or more specifically to variable energy loss of alpha particles to the detector from deposited material on the filter. A weakness of this approach is that thoron B (212Pb) does not have a detectable alpha parent and the next alpha progeny must decay through an isotope (212Bi) with a half-life of 60.6 min. This causes predictions of the 212Pb activity to lag in time to some extent. Mitigation of this effect is realized by using a first-order correction utilizing appropriate mathematical equations to account for the physics of this buildup and decay. This paper concludes by demonstrating that the beta assay value is a linear superposition of the alpha ROI values from the three dominant alpha peaks. Initial estimates on the coefficients of the alpha ROI values are derived with final values recommended to be determined from operational measurements.}, number={1}, journal={Nuclear Technology}, publisher={Informa UK Limited}, author={Hayes, Robert B.}, year={2009}, month={Oct}, pages={35–40} }
 @article{hayes_2009, title={Preliminary Benchmarking Efforts and MCNP Simulation Results for Homeland Security}, volume={168}, ISSN={0029-5450 1943-7471}, url={http://dx.doi.org/10.13182/nt09-a9318}, DOI={10.13182/nt09-a9318}, abstractNote={Abstract It is shown that basic measurements made from well-defined source detector configurations can be readily converted into benchmark quality results by which Monte Carlo N-Particle (MCNP) input stacks can be validated. Specifically, a recent measurement made in support of national security at the Nevada Test Site is described with sufficient detail to be submitted to the American Nuclear Society’s Joint Benchmark Committee for consideration as a radiation measurement benchmark. From this very basic measurement, MCNP input stacks are generated and validated both in predicted signal amplitude and spectral shape. Not modeled at this time are those perturbations from the more recent pulse-height-light tally feature, although what spectral deviations are seen can be partially attributed to not including this small correction. The value of this work is as a proof-of-concept demonstration that well-documented historical testing can be converted into formal radiation measurement benchmarks. This provides evidentiary support that validated virtual testing could eventually be carried out for various detection system technologies including algorithms, new detector designs, constructions, and arbitrary source and shielding assemblies.}, number={3}, journal={Nuclear Technology}, publisher={Informa UK Limited}, author={Hayes, Robert B.}, year={2009}, month={Dec}, pages={852–857} }
 @article{hayes_2008, title={High burn-up capability possibilities for a new beryllium moderated water cooled natural uranium reactor}, volume={35}, ISSN={0306-4549}, url={http://dx.doi.org/10.1016/j.anucene.2007.11.018}, DOI={10.1016/j.anucene.2007.11.018}, abstractNote={A recently conceived nuclear reactor design is evaluated here for theoretical burn-up characteristics which might support Global Nuclear Energy Partnership (GNEP) goals. This reactor uses natural uranium metal as fuel with beryllium moderation. The reactor also uses light water as a coolant. The reactor analysis in this work predicts the reactor to be capable of running at up to 4 GW-thermal for total burn-up values of approximately 1.4 × 103 GW-days. This is a very simple conceptual reactor design intended solely for very preliminary feasibility studies.}, number={8}, journal={Annals of Nuclear Energy}, publisher={Elsevier BV}, author={Hayes, Robert B.}, year={2008}, month={Aug}, pages={1584–1586} }
 @article{hayes_2008, title={PROBLEMS FOUND USING A RADON STRIPPING ALGORITHM FOR RETROSPECTIVE ASSESSMENT OF AIR FILTER SAMPLES}, volume={94}, DOI={10.1097/01.hp.0000296621.41740.3c}, abstractNote={An evaluation of a large number of air sample filters was undertaken using a commercial alpha and beta spectroscopy system employing a passive implanted planar silicon (PIPS) detector. Samples were only measured after air flow through the filters had ceased. Use of a commercial radon stripping algorithm was implemented to discriminate anthropogenic alpha activity on the filters from the radon progeny. When uncontaminated air filters were evaluated, the results showed that there was a time-dependent bias in both average estimates and measurement dispersion of anthropogenic activity estimates with the relative bias being small compared to the dispersion, indicating that the system would not give false positive indications for an appropriately set decision level. By also measuring environmental air sample filters simultaneously with electroplated alpha sources, use of the radon stripping algorithm demonstrated a number of substantial unexpected deviations from calibrated values indicating that the system would give false negative indications. Use of the current algorithm is, therefore, not recommended for general assay applications. Use of the PIPS detector should only be utilized for gross counting without appropriate modifications to the curve-fitting algorithm. As a screening method, the radon stripping algorithm might be expected to see elevated alpha activities from pure 239Pu on air sample filters (not due to radon progeny) around the 200 disintegrations per minute level.}, number={4}, journal={Health Physics}, publisher={Ovid Technologies (Wolters Kluwer Health)}, author={Hayes, Robert B.}, year={2008}, pages={366–372} }
 @article{alexander_swartz_amundson_blakely_buddemeier_gallez_dainiak_goans_hayes_lowry_et al._2007, title={BiodosEPR-2006 Meeting: Acute dosimetry consensus committee recommendations on biodosimetry applications in events involving uses of radiation by terrorists and radiation accidents}, volume={42}, ISSN={1350-4487}, url={http://dx.doi.org/10.1016/j.radmeas.2007.05.035}, DOI={10.1016/j.radmeas.2007.05.035}, abstractNote={In the aftermath of a radiological terrorism incident or mass-casualty radiation accident, first responders and receivers require prior guidance and pre-positioned resources for assessment, triage and medical management of affected individuals [NCRP, 2005. Key elements of preparing emergency responders for nuclear and radiological terrorism. NCRP Commentary No. 19, Bethesda, Maryland, USA]. Several recent articles [Dainiak, N., Waselenko, J.K., Armitage, J.O., MacVittie, T.J., Farese, A.M., 2003. The hematologist and radiation casualties. Hematology (Am. Soc. Hematol. Educ. Program) 473–496; Waselenko, J.K., MacVittie, T.J., Blakely, W.F., Pesik, N., Wiley, A.L., Dickerson, W.E., Tsu, H., Confer, D.L., Coleman, C.N., Seed, T., Lowry, P., Armitage, J.O., Dainiak, N., Strategic National Stockpile Radiation Working Group, 2004. Medical management of the acute radiation syndrome: recommendations of the Strategic National Stockpile Radiation Working Group. Ann. Intern. Med. 140(12), 1037–1051; Blakely, W.F., Salter, C.A., Prasanna, P.G., 2005. Early-response biological dosimetry—recommended countermeasure enhancements for mass-casualty radiological incidents and terrorism. Health Phys. 89(5), 494–504; Goans, R.E., Waselenko, J.K., 2005. Medical management of radiation casualties. Health Phys. 89(5), 505–512; Swartz, H.M., Iwasaki, A., Walczak, T., Demidenko, E., Salikhov, I., Lesniewski, P., Starewicz, P., Schauer, D., Romanyukha, A., 2005. Measurements of clinically significant doses of ionizing radiation using non-invasive in vivo EPR spectroscopy of teeth in situ. Appl. Radiat. Isot. 62, 293–299; Weisdorf, D., Chao, N., Waselenko, J.K., Dainiak, N., Armitage, J.O., McNiece, I., Confer, D., 2006. Acute radiation injury: contingency planning for triage, supportive care, and transplantation. Biol. Blood Marrow Transplant. 12(6), 672–682], national [National Council of Radiation Protection and Measurements (NCRP), 1994. Management of persons accidentally contaminated with radionuclides. NCRP Report No. 65, Bethesda, Maryland, USA; NCRP, 2001. Management of terrorist events involving radioactive material. NCRP Report No. 138, Bethesda, Maryland, USA; NCRP, 2005. Key elements of preparing emergency responders for nuclear and radiological terrorism. NCRP Commentary No. 19, Bethesda, Maryland, USA] and international [IAEA, 2005. Generic procedures for medical response during a nuclear or radiological emergency. EPR-Medical 2005, IAEA, Vienna, Austria] agencies have reviewed strategies for acute-phase biodosimetry. Consensus biodosimetric guidelines include: (a) clinical signs and symptoms, including peripheral blood counts, time to onset of nausea and vomiting and presence of impaired cognition and neurological deficits, (b) radioactivity assessment, (c) personal and area dosimetry, (d) cytogenetics, (e) in vivo electron paramagnetic resonance (EPR) and (f) other dosimetry approaches (i.e. blood protein assays, etc.). Emerging biodosimetric technologies may further refine triage and dose assessment strategies. However, guidance is needed regarding which biodosimetry techniques are most useful for different radiological scenarios and consensus protocols must be developed. The Local Organizing Committee for the Second International Conference on Biodosimetry and Seventh International Symposium on EPR Dosimetry and Applications (BiodosEPR-2006 Meeting) convened an Acute Dosimetry Consensus Committee composed of national and international experts to: (a) review the current literature for biodosimetry applications for acute-phase applications in radiological emergencies, (b) describe the strengths and weaknesses of each technique, (c) provide recommendations for the use of biodosimetry assays for selected defined radiation scenarios, and (d) develop protocols to apply these recommended biological dosimetry techniques with currently available supplies and equipment for first responders. The Acute Dosimetry Consensus Committee developed recommendations for use of a prioritized multiple-assay biodosimetric-based strategy, concluding that no single assay is sufficiently robust to address all of the potential radiation scenarios including management of mass casualties and diagnosis for early medical treatment. These recommendations may be used by first responders/first receivers that span time-windows of (i.e. 0–5 days) after the radiological incident for three radiological scenarios including: (a) radiation exposure device (RED), (b) radiological dispersal device (RDD), and (c) an improvised (or otherwise acquired) nuclear device (IND). Consensus protocols for various bioassays (i.e. signs and symptoms recording, bioassay sampling for radioactivity analysis, nail-clipping sampling for EPR analysis and blood collection for hematology, cytogenetics, and blood chemistry analyses) are presented as Appendix materials. As stated in NCRP Commentary No. 19 [NCRP, 2005. Key elements of preparing emergency responders for nuclear and radiological terrorism. NCRP Commentary No. 19, Bethesda, Maryland, USA], multi-parameter triage (i.e. time to vomiting, lymphocyte kinetics, and other biodosimetry indicators) offers the current best strategy for early assessment of absorbed dose.}, number={6-7}, journal={Radiation Measurements}, publisher={Elsevier BV}, author={Alexander, George A. and Swartz, Harold M. and Amundson, Sally A. and Blakely, William F. and Buddemeier, Brooke and Gallez, Bernard and Dainiak, Nicholas and Goans, Ronald E. and Hayes, Robert B. and Lowry, Patrick C. and et al.}, year={2007}, month={Jul}, pages={972–996} }
 @article{hayes_2007, title={Burn-up characteristics of a light-water-cooled nuclear reactor of natural uranium and beryllium}, volume={1}, ISBN={1936-6256}, number={2}, journal={Journal of Physical & Natural Science}, author={Hayes, RB}, year={2007}, pages={1–11} }
 @article{sato_filas_eaton_eaton_romanyukha_hayes_rossi_2007, title={Electron spin relaxation of radicals in irradiated tooth enamel and synthetic hydroxyapatite}, volume={42}, ISSN={1350-4487}, url={http://dx.doi.org/10.1016/j.radmeas.2007.05.048}, DOI={10.1016/j.radmeas.2007.05.048}, abstractNote={Abstract Spin–lattice relaxation times, T 1 , for EPR signals created by irradiation of tooth enamel or carbonate-doped hydroxyapatite were studied by three-pulse inversion recovery and long-pulse saturation recovery. The recovery curves were modeled as the sum of two log-normal distributions of relaxation times. The dominant component in the EPR signal for tooth samples is assigned to CO 2 - replacing phosphate (B-sites) in the hydroxyapatite matrix. For this component the center of the T 1 distribution was 1.4 – 1.6 μ s at 294 K, and did not vary significantly with radiation dose or the source of the sample. The smaller, slower relaxing, component of the signals from the tooth samples had a T 1 distribution centered at 30 – 60 μ s and is assigned to an organic radical ( g ∼ 2.0045 ) . At 294 K the spin–spin relaxation time T 2 measured by two-pulse echo decay was dominated by motion of the CO 2 - and was independent of dose. The dose independence of T 1 and T 2 at ambient temperature provides the basis for using dose-independent microwave powers to record dosimetric tooth signals at microwave powers above the linear response regime.}, number={6-7}, journal={Radiation Measurements}, publisher={Elsevier BV}, author={Sato, Hideo and Filas, Benjamen A. and Eaton, Sandra S. and Eaton, Gareth R. and Romanyukha, Alex A. and Hayes, Robert and Rossi, Alexandre M.}, year={2007}, month={Jul}, pages={997–1004} }
 @article{dean_hayes_2006, title={A Light-Water-Cooled Nuclear Reactor of Natural Uranium and Beryllium}, volume={3}, ISSN={1546-962X}, url={http://dx.doi.org/10.1520/jai100274}, DOI={10.1520/jai100274}, abstractNote={A light-water nuclear power reactor core configuration is described, which does not require any isotopic enrichments (e.g., D2O or U-235) without the use of graphite. This reactor design utilizes plates of natural uranium (NU) metal and Beryllium. The coolant is natural water, which flows between two plates of NU and is required to add additional moderator to attain criticality. Only square reactor shapes of uniform plate thickness are evaluated. Commercial viability is not demonstrated but the proposed design does warrant further study. The configuration shows potential to meet GEN IV sustainability and GNEP closed fuel cycle goals. Aspects covered include neutronics, criticality, costs and nonproliferation.}, number={8}, journal={Journal of ASTM International}, publisher={ASTM International}, author={Dean, SW and Hayes, R}, year={2006}, pages={100274} }
 @article{hayes_2005, title={Collimated spectroscopy for specific activity determination behind a shield wall}, volume={39}, DOI={10.1016/j.radmeas.2004.06.005}, abstractNote={When radioactive materials are placed behind shield walls where the actual specific activity is not known (such as high dose rate waste containers or highly contaminated glove boxes), remote assay can be highly desirable. This paper walks through a theoretical analysis technique whereby an assay calculation can be carried out via collimated spectroscopy. This is done using standard approximations of homogeneous sources, source matrices, perfect collimation and accurately known geometric material distributions. All solutions are given in closed form when appropriate approximating functions are used.}, number={1}, journal={Radiation Measurements}, publisher={Elsevier BV}, author={Hayes, Robert B.}, year={2005}, month={Jan}, pages={43–46} }
 @article{hayes_pe??a_goff_2005, title={USE OF ALPHA SPECTROSCOPY FOR CONDUCTING RAPID SURVEYS OF TRANSURANIC ACTIVITY ON AIR SAMPLE FILTERS AND SMEARS}, volume={89}, ISSN={0017-9078}, url={http://dx.doi.org/10.1097/01.hp.0000156959.35525.57}, DOI={10.1097/01.hp.0000156959.35525.57}, abstractNote={This paper demonstrates the utility of a portable alpha Continuous Air Monitor (CAM) as a bench top scalar counter for multiple sample types. These include using the CAM to count fixed air sample filters and radiological smears. In counting radiological smears, the CAM is used very much like a gas flow proportional counter (GFPC), albeit with a lower efficiency. Due to the typically low background in this configuration, the minimum detectable activity for a 5-min count should be in the range of about 10 dpm which is acceptably below the 20 dpm limit for transuranic isotopes. When counting fixed air sample filters, the CAM algorithm along with other measurable characteristics can be used to identify and quantify the presence of transuranic isotopes in the samples. When the radiological control technician wants to take some credit from naturally occurring radioactive material contributions due to radon progeny producing higher energy peaks (as in the case with a fixed air sample filter), then more elaborate techniques are required. The techniques presented here will generate a decision level of about 43 dpm for such applications. The calibration for this application should alternatively be done using the default values of channels 92–126 for region of interest 1. This can be done within 10 to 15 min resulting in a method to rapidly evaluate air filters for transuranic activity. When compared to the 1-h count technique described by Hayes (2004), the technique presented in the present work demonstrates a technique whereby more than two thirds of samples can be rapidly shown (within 10 to 15 min) to be within regulatory compliant limits. In both cases, however, spectral quality checks are required to insure sample self attenuation is not a significant bias in the activity estimates. This will allow the same level of confidence when using these techniques for activity quantification as is presently available for air monitoring activity quantification using CAMs.}, number={2}, journal={Health Physics}, publisher={Ovid Technologies (Wolters Kluwer Health)}, author={Hayes, Robert B. and Pe??a, Adan M. and Goff, Thomas E.}, year={2005}, month={Aug}, pages={172–180} }
 @article{kenner_brik_liu_haskell_hayes_knight_vajda_miller_jee_barrus_2005, title={Variation of long-lived free radicals responsible for the EPR native signal in bone of aged or diseased human females and ovariectomized adult rats}, volume={39}, DOI={10.1016/j.radmeas.2004.01.040}, abstractNote={The purpose of this study was to gain insights into the variations seen in the electron paramagnetic resonance (EPR) spectroscopy of the native signals of teeth and bones used for retrospective dosimetry measurements. We determined that changes occur in the long-lived free radicals responsible for the native signal of cortical bone in aging or diseased human females and aged ovariectomized rats. This was done by measuring the magnitude of the broad (BC) and narrow (NC) components of the native EPR signal of bone following chemical extraction, aging, crushing and thermal annealing. Bone from the upper midshaft of femora of young (17–34 years old, n=5) and elderly (70–92 years old, n=18) females was examined. The results showed that the elderly women had significantly higher BC than the younger women (P<0.01). A similar interpretation was made of the data from an aging female rat osteoporosis model. The results for the NC signals were similar. Finally, dramatic decreases in both NC and BC signals were seen in HIV positive and uncontrolled diabetic (one each) patients indicating the need for studying this signal for a broad spectrum of metabolic disorders. Experiments were performed which strongly indicate that iron liganded with organic molecules is the source of the BC signal. Finally, the accuracy achieved in this study indicates that resolving the dosimetric signal (g=2.0018) should be improved by subtraction of the deconvoluted NC and BC signals from the original spectrum.}, number={3}, journal={Radiation Measurements}, publisher={Elsevier BV}, author={Kenner, G.H. and Brik, A.B. and Liu, G. and Haskell, E.H. and Hayes, R.B. and Knight, J.A. and Vajda, E.G. and Miller, S.C. and Jee, W.S.S. and Barrus, J.K.}, year={2005}, month={Jun}, pages={255–262} }
 @article{hayes_2004, title={A NEW TECHNIQUE FOR PRELIMINARY ESTIMATES OF TRU ACTIVITY ON AIR SAMPLE FILTERS AND RADIOLOGICAL SMEARS}, volume={87}, DOI={10.1097/00004032-200410000-00011}, abstractNote={In most nuclear facilities, fixed air samplers and sometimes portable air samplers are used where some probability of a release exists but is not expected, and so the added expense and effort of using a continuous air monitor is not deemed justified. When a release is suspected, naturally occurring radioactive material buildup on the filter typically prevents any quantitative measurements within the first day or so. Likewise, outdoor air measurements suffer from the same limitations (such as those taken during the Los Alamos fires) and so any rapid quantifiable measurements of fixed air sampler/portable air sampler filters which are technically defendable (even though conservative) are of use. The technique presented here is only intended for use in routine health physics survey applications and does not presently appear to be appropriate for sub pico Curie activity determinations. This study evaluates the utility of using a portable continuous air monitor as an alpha spectrometer to make transuranic activity determinations of samples using both the built in algorithm for air monitoring and a simple region of interest analysis. All samples evaluated were from air sample filters taken using a portable air sampler. Samples were taken over many months to quantify effects from natural variation in radon progeny activity distributions.}, number={4}, journal={Health Physics}, publisher={Ovid Technologies (Wolters Kluwer Health)}, author={Hayes, Robert}, year={2004}, pages={429–436} }
 @article{hayes_chiou_2004, title={CURVE FITTING AIR SAMPLE FILTER DECAY CURVES TO ESTIMATE TRANSURANIC CONTENT}, volume={86}, DOI={10.1097/00004032-200401000-00010}, abstractNote={Abstract— By testing industry standard techniques for radon progeny evaluation on air sample filters, a new technique is developed to evaluate transuranic activity on air filters by curve fitting the decay curves. The industry method modified here is simply the use of filter activity measurements at different times to estimate the air concentrations of radon progeny. The primary modification was to not look for specific radon progeny values but rather transuranic activity. By using a method that will provide reasonably conservative estimates of the transuranic activity present on a filter, some credit for the decay curve shape can then be taken. By carrying out rigorous statistical analysis of the curve fits to over 65 samples having no transuranic activity taken over a 10-mo period, an optimization of the fitting function and quality tests for this purpose was attained.}, number={1}, journal={Health Physics}, publisher={Ovid Technologies (Wolters Kluwer Health)}, author={Hayes, Robert B. and Chiou, Hung Cheng}, year={2004}, month={Jan}, pages={80–91} }
 @article{chiou_hayes_2004, title={Creating a baseline radiological standard for the waste isolation pilot plant underground}, volume={40}, ISSN={1025-6016 1477-2639}, url={http://dx.doi.org/10.1080/10256010410001678053}, DOI={10.1080/10256010410001678053}, abstractNote={The Waste Isolation Pilot Plant (WIPP) is a deep underground geological repository for defense transuranic wastes. The creation of a full baseline radiological standard for the WIPP underground is essential in order to evaluate and account for the influence of the naturally occurring radioactive materials, and to prepare for any suspected contamination or the very unlikely event of a real accident scenario. In this report, we describe the establishment of the baseline information using the gamma background dose rate measurements and the salt rib smears of surface removable alpha and beta activities throughout the WIPP underground. The average background gamma dose rate in the WIPP underground is 8.27 × 10−9 ± 1.65 × 10−9 Gy/h while the gamma dose rate on the WIPP surface is 3.46 × 10−8 ± 1.65 × 10−9 Gy/h. The overall surface average alpha activity in the underground is 8.52 × 10−5 ± 1.22 × 10−4 Bq/cm2 (at 1σ level) with the minimum detectable activity (MDA) of 4.81 × 10−4 Bq/cm2. The overall surface average beta activity is 8.25 × 10−4 ± 8.17 × 10−4 Bq/cm2 (at 1σ level) with the MDA of 3.19 × 10−3 Bq/cm2. This baseline standard will be beneficial to the overall WIPP operational facility, ensuring the worker safety and adding to public confidence in the operation of the WIPP.}, number={3}, journal={Isotopes in Environmental and Health Studies}, publisher={Informa UK Limited}, author={Chiou, Hung-Cheng and Hayes, Robert}, year={2004}, month={Sep}, pages={213–220} }
 @article{hayes_2004, title={Generalized photon skyshine calculations}, volume={111}, DOI={10.1093/rpd/nch342}, abstractNote={The energy-dependent dose contributions from monoenergetic photon source points located 1.5 m above the ground have been tabulated. These values are intended to be used for regulatory compliance with site boundary dose limitations and as such are all presented in effective dose units. Standard air and soil are modelled where the air has vertical density gradient approximation. Energies from 0.05 up to 10 MeV are evaluated for dose transport up to 40 mean free paths.}, number={3}, journal={Radiation Protection Dosimetry}, author={Hayes, RB}, year={2004}, pages={251–256} }
 @inproceedings{rhoden_hayes_2003, title={Alternate Approach to the Upper Subcritical Limit Determination for MCNP}, volume={89}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0346904404&partnerID=MN8TOARS}, booktitle={Transactions of the American Nuclear Society}, author={Rhoden, W.G. and Hayes, R.}, year={2003}, pages={109} }
 @inproceedings{hayes_strait_2003, title={Collimated Spectroscopy for Specific Activity Determination Behind a Shield Wall}, volume={89}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0346904210&partnerID=MN8TOARS}, booktitle={Transactions of the American Nuclear Society}, author={Hayes, R.B. and Strait, A.E.}, year={2003}, pages={566} }
 @article{hayes_2003, title={Diagnostic X ray dose profiles in molar teeth using Monte Carlo simulation}, volume={104}, ISSN={0144-8420 1742-3406}, url={http://dx.doi.org/10.1093/oxfordjournals.rpd.a006175}, DOI={10.1093/oxfordjournals.rpd.a006175}, abstractNote={The dose profiles in molar teeth from diagnostic X rays was calculated using the Monte Carlo software program MCNP4c2. The information calculated supports needs in EPR retrospective dosimetry to account for diagnostic X ray exposures in teeth. Only tooth positions 6, 7 and 8 were simulated (the three teeth furthest back including the wisdom teeth) using a very detailed model of the pertinent physiology. The lingual and buccal halves of teeth were evaluated as were the crown dentin and roots in tooth position 7. Linear dose profiles through the enamel were also calculated.}, number={2}, journal={Radiation Protection Dosimetry}, publisher={Oxford University Press (OUP)}, author={Hayes, R.}, year={2003}, month={May}, pages={153–158} }
 @article{hayes_2003, title={False CAM Alarms from Radon Fluctuations}, volume={85}, DOI={10.1097/00004032-200311002-00008}, abstractNote={The root cause of many false continuous air monitor (CAM) alarms is revealed for CAMs that use constant spectral shape assumptions in transuranic (TRU) alpha activity determination algorithms. This paper shows that when atmospheric radon levels continually decrease and bottom out at a minimum level, reduced false TRU count rates are not only expected but measured. Similarly, when the radon levels continually increase to a maximum level, elevated false TRU count rates were measured as predicted. The basis for expecting this dependence on changes in radon levels is discussed.}, journal={Health Physics}, publisher={Ovid Technologies (Wolters Kluwer Health)}, author={Hayes, Robert}, year={2003}, pages={S81–S84} }
 @article{hayes_chiou_2003, title={Preliminary Evaluation of Real Time False CAM Alarm Prediction Through Continuous Radon Monitoring}, volume={84}, DOI={10.1097/00004032-200305001-00012}, abstractNote={The outputs of two real-time radon monitors were compared with the output from a continuous air monitor (CAM) to evaluate the potential of predicting false CAM alarms. From the results obtained, it appears that the radon monitor will be able to indicate when large rapid changes in radon levels are occurring before the effect on a CAM has taken place.}, journal={Health Physics}, publisher={Ovid Technologies (Wolters Kluwer Health)}, author={Hayes, Robert and Chiou, Hung Cheng}, year={2003}, pages={S89–S92} }
 @article{hayes_haskell_kenner_2002, title={AN EPR MODEL FOR SEPARATING INTERNAL 90SR DOSES FROM EXTERNAL GAMMA-RAY DOSES IN TEETH}, volume={83}, DOI={10.1097/00004032-200207000-00008}, abstractNote={The problem of retrospectively measuring radiation doses to humans having both external and internal exposures is addressed. A simplified theoretical model is presented by which the internal exposure from a bone seeking radionuclide can be measured and distinguished from an external gamma-ray dose. The model also provides a means of estimating initial acute uptakes of 90Sr.}, number={1}, journal={Health Physics}, publisher={Ovid Technologies (Wolters Kluwer Health)}, author={Hayes, Robert B. and Haskell, Edwin H. and Kenner, Gerry H.}, year={2002}, pages={75–81} }
 @article{hayes_beekman_2002, title={Alpha CAM alarm set points in a salt dust environment}, volume={82}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0036104290&partnerID=MN8TOARS}, DOI={10.1097/00004032-200206000-00019}, abstractNote={While considering the regulatory and site specific requirements for Continuous Air Monitor responses in the Waste Isolation Pilot Plant underground (which is a salt mine), a number of issues relating to the buildup of salt (NaCl) on the filters must be considered when determining the alarm set points. As the Waste Isolation Pilot Plant is a Department of Energy facility, alarm set point determination must be made in light of the regulatory drivers and physical limitations found when monitoring for airborne contamination in an underground salt mine. The use of dual alarm set points is also exploited to implement a graded approach to alarm responses.}, number={6}, journal={Health Physics}, publisher={Ovid Technologies (Wolters Kluwer Health)}, author={Hayes, Robert B. and Beekman, Marsha L.}, year={2002}, pages={887–897} }
 @article{hayes_2002, title={Beta CAM alarm set-point determination using historical data at the WIPP}, volume={19}, journal={Radiation Protection Management}, author={Hayes, R.}, year={2002}, pages={16–24} }
 @article{hayes_2002, title={DOSE RATE PREDICTION METHODOLOGY FOR REMOTE HANDLED TRANSURANIC WASTE WORKERS AT THE WASTE ISOLATION PILOT PLANT}, volume={83}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0036777960&partnerID=MN8TOARS}, DOI={10.1097/00004032-200210000-00002}, abstractNote={Abstract— An approach is described for estimating future dose rates to Waste Isolation Pilot Plant workers processing remote handled transuranic waste. The waste streams will come from the entire U.S. Department of Energy complex and can take on virtually any form found from the processing sequences for defense-related production, radiochemistry, activation and related work. For this reason, the average waste matrix from all generator sites is used to estimate the average radiation fields over the facility lifetime. Innovative new techniques were applied to estimate expected radiation fields. Non-linear curve fitting techniques were used to predict exposure rate profiles from cylindrical sources using closed form equations for lines and disks. This information becomes the basis for Safety Analysis Report dose rate estimates and for present and future ALARA design reviews when attempts are made to reduce worker doses.}, number={4}, journal={Health Physics}, publisher={Ovid Technologies (Wolters Kluwer Health)}, author={Hayes, Robert}, year={2002}, pages={449–455} }
 @article{hayes_gadbury_goff_2002, title={Preliminary Measurements of Surface Removable NORM Activity in the WIPP Underground}, volume={82}, DOI={10.1097/00004032-200205001-00015}, abstractNote={The results of correlating surface removable activity to that measured on a fixed air sampler is reported. It was found from over 40 smears taken during a two week period that surface removable activity from Naturally Occurring Radioactive Material (NORM) can be predicted to be within a factor of 2 or 3 using either a fixed air sampler measurement or even another smear measurement from a specified surface. The method is being used to take credit for background surface removable activity in similar fashion to a background count for any other radiation detector. The utility of this technique is also discussed from an operational health physics perspective for the Waste Isolation Pilot Plant.}, number={Supplement}, journal={Health Physics}, publisher={Ovid Technologies (Wolters Kluwer Health)}, author={Hayes, Robert and Gadbury, Casey and Goff, Tom}, year={2002}, pages={S103–S107} }
 @article{goff_hayes_2001, title={Internal contamination evaluation of a radioactive materials shipping container using a radiation assessment filter}, volume={18}, number={6}, journal={Radiation Protection Management}, author={Goff, T and Hayes, R}, year={2001}, pages={30–38} }
 @article{hayes_haskell_2000, title={A method for identification of interfering signals in EPR dating of tooth enamel}, volume={32}, ISSN={1350-4487}, url={http://dx.doi.org/10.1016/s1350-4487(00)00108-6}, DOI={10.1016/s1350-4487(00)00108-6}, abstractNote={Abstract In this paper, a method for identifying interfering EPR signals in fossil tooth enamel is presented. This method consists of optimizing EPR parameters to enhance spectral resolution of the fossil signals followed by a g -factor and intensity normalized subtraction of a high-dosed, modern tooth enamel sample spectrum. By scanning the modern tooth enamel sample with the same parameters as the fossil sample, the difference spectrum of the fossil and modern irradiated tooth enamel samples can resolve numerous hyperfine and other interfering signals. This method was successfully applied to a fossil sample studied elsewhere (Grun, R., 1998a. Ancient TL 16, 51–55; Grun, R., Clapp, R., 1996. Ancient TL 14, 1–5; Martin Jonas, 1997. Ph.D. Thesis, Cambridge University; Jonas, M., Grun, R., 1997. Radiat. Meas. 27, 49–58; Vanhaelewyn et al., 2000. Appl. Radiat. Isot. 52, 1317–1326). This sample has shown discrepancies in dose estimations obtained from the power absorption curve versus those obtained from the first derivative spectra (Grun, R., 1998b. Radiat. Meas. 29, 177–193). The reason for this, and other discrepancies, are accounted for by the signals resolved using the method presented here.}, number={5-6}, journal={Radiation Measurements}, publisher={Elsevier BV}, author={Hayes, Robert B. and Haskell, Edwin H.}, year={2000}, month={Dec}, pages={781–785} }
 @article{hayes_haskell_kenner_barrus_2000, title={A virtually nondestructive EPR technique accounting for diagnostic X-rays}, volume={32}, ISSN={1350-4487}, url={http://dx.doi.org/10.1016/S1350-4487(00)00118-9}, DOI={10.1016/s1350-4487(00)00118-9}, abstractNote={We have implemented the method proposed by Aldrich and Pass (Aldrich, J.E., Pass, B., 1988. Determining radiation exposure from nuclear accidents and atomic tests using dental enamel. Health Phys. 54, 469–471.) to measure both the interior and exterior portions of a tooth in order to determine the diagnostic X-ray component of the total dose in the teeth. This was done using a modified nondestructive approach of Haskell et al. (Haskell, E.H., Hayes, R.B., Romanyukha, A.A., Kenner, G.H., 2000. Preliminary report on the development of a virtually non-destructive additive dose technique for EPR dosimetry Appl. Radiat Isot. 52, 1065–1070.) given in Hayes et al. (Hayes, R.B., Haskell, E.H., Barrus, J.K., Kenner, G.H., Romanyukha, A.A., 2000. Accurate EPR radiosensitivity calibration using small sample masses. Nucl. Instr. Meth. A. 441, 535–550). Here only 5% of the total tooth enamel sample from an enamel crown was used for individual sample sensitivity calibration. A cavity response correction for the low mass samples was also used (Hayes et al., 2000). The teeth were American wisdom teeth having unknown doses applied by the IAEA in the range of 0 to 1 Gy as part of the second international intercomparison (Wieser, A., Mehta, K., Amira, S., Aragno, S., Bercea, S., Brik, A., Bugai, A., Callens, F., Chumak, V., Ciesielski, B., Debuyst, R., Dubovsky, S., Duliu, O., Fattibene, P., Haskell, E., Hayes, R., Ignatiev, E., Ivannikov, A., Kirillov, V., Kleschenko, E., Nakamura, N., Nathe, M., Nowak, J., Onori, S., Pass, B., Pivovarov, S., Romanyukha, A., Scherbina, O., Shames, A., Sholom, S., Skvortsov, V., Stepanenko, V., Tikounov, D., Toyoda, S., 2000. The 2nd international intercomparison on EPR tooth dosimetry. Radiat. Meas. in press). Final dose reconstruction estimates of the IAEA applied values showed a very high correlation (R=0.996). The approximate excess dose measured on the outside of the teeth relative to the inside was 49±35 mGy which is attributed to the diagnostic X-ray exposure given to the America wisdom teeth prior to extraction. The method used showed only a small dependence on the accelerating voltage of the X-ray source.}, number={5-6}, journal={Radiation Measurements}, publisher={Elsevier BV}, author={Hayes, Robert B. and Haskell, Edwin H. and Kenner, Gerry H. and Barrus, Jeffrey K.}, year={2000}, month={Dec}, pages={559–566} }
 @article{hayes_haskell_barrus_kenner_romanyukha_2000, title={Accurate EPR radiosensitivity calibration using small sample masses}, volume={441}, DOI={10.1016/s0168-9002(99)00976-6}, abstractNote={We demonstrate a procedure in retrospective EPR dosimetry which allows for virtually nondestructive sample evaluation in terms of sample irradiations. For this procedure to work, it is shown that corrections must be made for cavity response characteristics when using variable mass samples. Likewise, methods are employed to correct for empty tube signals, sample anisotropy and frequency drift while considering the effects of dose distribution optimization. A demonstration of the method's utility is given by comparing sample portions evaluated using both the described methodology and standard full sample additive dose techniques. The samples used in this study are tooth enamel from teeth removed during routine dental care. We show that by making all the recommended corrections, very small masses can be both accurately measured and correlated with measurements of other samples. Some issues relating to dose distribution optimization are also addressed.}, number={3}, journal={Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment}, publisher={Elsevier BV}, author={Hayes, R.B. and Haskell, E.H. and Barrus, J.K. and Kenner, G.H. and Romanyukha, A.A.}, year={2000}, month={Mar}, pages={535–550} }
 @article{hayes_haskell_wieser_romanyukha_hardy_barrus_2000, title={Assessment of an alanine EPR dosimetry technique with enhanced precision and accuracy}, volume={440}, DOI={10.1016/s0168-9002(99)00957-2}, abstractNote={Dose reconstruction in the course of a series of blind tests demonstrated that an accuracy of 10 mGy for low doses and 1% for high doses can be achieved using EPR spectroscopy. This was accomplished using a combination of methodologies including polynomial filtration of the EPR spectrum, dosimeter rotation during scanning, use of an EPR standard fixed into the resonator and subtraction of all nonradiogenic signals. Doses were reconstructed over the range of 0.01–1000 Gy using this compound spectral EPR analysis. This EPR technique, being equally applicable to fractionated doses (such as those delivered during multiple radiotherapy treatments), was verified to exhibit dose reciprocity. Irradiated alanine dosimeters which were stored exhibited compound spectral EPR signal fading of ca 3% over 9 months. All error estimates given in this paper are given at the 1 standard deviation level and unless otherwise specified do not account for uncertainties in source calibration.}, number={2}, journal={Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment}, publisher={Elsevier BV}, author={Hayes, Robert B. and Haskell, Edwin H. and Wieser, Albrecht and Romanyukha, Alexander A. and Hardy, Byron L. and Barrus, Jeffrey K.}, year={2000}, month={Feb}, pages={453–461} }
 @article{wieser_onori_aragno_fattibene_romanyukha_ignatiev_koshta_skvortzov_ivannikov_stepanenko_et al._2000, title={Comparison of sample preparation and signal evaluation methods for EPR analysis of tooth enamel}, volume={52}, DOI={10.1016/s0969-8043(00)00050-6}, abstractNote={In dose reconstruction by EPR dosimetry with teeth various methods are applied to prepare tooth enamel samples and to evaluate the dosimetric signal. A comparison of seven frequently used methods in EPR dosimetry with tooth enamel was performed. The participating Institutes have applied their own procedure to prepare tooth enamel samples and to evaluate the dosimetric signal. The precision of the EPR measurement and the dependence of the estimated dosimetric signal with irradiation up to 1000 mGy were compared. The obtained results are consistent among the different methods. The reproducibility of the dosimetric signal and its estimated relation with the absorbed dose was found to be very close for the applied methods with one possible exception.}, number={5}, journal={Applied Radiation and Isotopes}, publisher={Elsevier BV}, author={Wieser, A and Onori, S and Aragno, D and Fattibene, P and Romanyukha, A and Ignatiev, E and Koshta, A and Skvortzov, V and Ivannikov, A and Stepanenko, V and et al.}, year={2000}, month={May}, pages={1059–1064} }
 @article{sholom_haskell_hayes_chumak_kenner_2000, title={EPR-dosimetry with carious teeth}, volume={32}, ISSN={1350-4487}, url={http://dx.doi.org/10.1016/s1350-4487(00)00064-0}, DOI={10.1016/s1350-4487(00)00064-0}, abstractNote={The effect of caries in EPR dosimetry of tooth enamel (in the dose range of 0–1 Gy) was investigated. The enamel of each tooth was divided into carious, non-carious and intermediate portions. The EPR signals of enamel at g = 2.0018 (dosimetric) and g = 2.0045 (native) were examined. The intensity of the dosimetric signal was the same for all three portions, while that of the native signal was higher for carious portions than for non-carious and intermediate portions. Reconstruction of the laboratory applied doses was done using all portions. Reasonable correlation between nominal and reconstructed doses was found in most cases. The effect of alkali treatment on the native and dosimetric signals of enamel was also tested. Reduction of the native signal intensity, particularly in the carious portions, was found to be the only significant effect. This resulted in a slight improvement in the accuracy of the reconstructed doses.}, number={5-6}, journal={Radiation Measurements}, publisher={Elsevier BV}, author={Sholom, S.V. and Haskell, E.H. and Hayes, R.B. and Chumak, V.V. and Kenner, G.H.}, year={2000}, month={Dec}, pages={799–803} }
 @article{haskell_hayes_romanyukha_kenner_2000, title={Preliminary report on the development of a virtually nondestructive additive dose technique for EPR dosimetry}, volume={52}, DOI={10.1016/s0969-8043(00)00049-x}, abstractNote={We propose a new approach to the additive dose method in EPR dosimetry studies for tooth enamel specimens. We outline a specialized routine whereby the sample may be left for the most part unirradiated, while only a small aliquot of the sample will be additively irradiated to relatively large doses. The routine is done in such a way so as not to significantly compromise either precision or accuracy of the dose reconstruction. It is also demonstrated that the overall throughput of the dose reconstruction is not appreciably compromised. With this potential ability, the utility of an international dose/sensitivity standard for EPR dosimetry of teeth is considered.}, number={5}, journal={Applied Radiation and Isotopes}, publisher={Elsevier BV}, author={Haskell, Edwin H and Hayes, Robert B and Romanyukha, Alexander A and Kenner, Gerry H}, year={2000}, month={May}, pages={1065–1070} }
 @article{wieser_mehta_amira_aragno_bercea_brik_bugai_callens_chumak_ciesielski_et al._2000, title={The second international intercomparison on EPR tooth dosimetry}, volume={32}, ISSN={1350-4487}, url={http://dx.doi.org/10.1016/s1350-4487(00)00060-3}, DOI={10.1016/s1350-4487(00)00060-3}, abstractNote={Eighteen international EPR laboratories participated in the second intercomparison programme. Each participant had to prepare enamel samples and evaluate the absorbed dose from molars that were irradiated in vitro in the range 0–1000 mGy. The objective of the programme was to bring together all methods which are currently applied by different laboratories for EPR dose reconstruction and to demonstrate the present state of dosimetry. An overview of the essential features of the different methods is presented. The current accuracy of EPR tooth enamel dosimetry under defined conditions of irradiation is evaluated.}, number={5-6}, journal={Radiation Measurements}, publisher={Elsevier BV}, author={Wieser, A. and Mehta, K. and Amira, S. and Aragno, D. and Bercea, S. and Brik, A. and Bugai, A. and Callens, F. and Chumak, V. and Ciesielski, B. and et al.}, year={2000}, month={Dec}, pages={549–557} }
 @article{haskell_difley_kenner_hayes_snyder_gustafson_1999, title={A comparison of optically stimulated luminescence dating methods applied to Eolian sands from the Mojave desert in Southern Nevada}, volume={18}, ISSN={0277-3791}, url={http://dx.doi.org/10.1016/s0277-3791(98)00057-2}, DOI={10.1016/s0277-3791(98)00057-2}, abstractNote={Optical dating methods were applied to eolian quartz and feldspar grains taken from near-surface locations in the Mojave Desert in southern Nevada, U.S.A. Three separate sites, all believed to have originated from the same geological event were sampled. Multiple aliquot methods as well as a single aliquot method (the ‘single aliquot regeneration, added dose’ or SARA technique) were applied. Variations on these methods included different pre-heat treatments for the additive dose technique and optical and thermal resets for the SARA technique. An automated routine was developed for use with the SARA analyses, and a new method of correcting for partial bleaching was also developed and tested. The greatest variations in results were seen with the multiple aliquot methods. Mean ages varied from 7.8±0.7 ka for the SARA technique applied to quartz to 6.1±1.6 ka for the SARA technique applied to feldspar samples. Results of the multiple aliquot technique using quartz was 7.4±2.9 ka and 7.4±4.0 ka for the 220°C pre-heat for 5 min and 160°C pre-heat for 16 h, respectively.}, number={2}, journal={Quaternary Science Reviews}, publisher={Elsevier BV}, author={Haskell, E. and Difley, R. and Kenner, G. and Hayes, R. and Snyder, K. and Gustafson, D.}, year={1999}, month={Feb}, pages={235–242} }
 @article{haskell_hayes_kenner_wieser_aragno_fattibene_onori_1999, title={Achievable Precision and Accuracy in EPR Dosimetry of Tooth Enamel}, volume={84}, DOI={10.1093/oxfordjournals.rpd.a032792}, abstractNote={The utility of combining various methodologies is examined to remove systematically or correct for the major instrumental effects which introduce uncertainties in EPR dosimetry of tooth enamel. The result is a relatively high precision method that can be successfully transferred between laboratories. Only an ideal case was considered in this study whereby the actual native signal prior to irradiation was used as the empirical zero in each individual dose response. To prove its general value, the overall methodology was applied to seven teeth of differing quality, prepared using different methodologies, and measured in three laboratories using different EPR spectrometers. Using this approach to characterise the utility of both the methodology and instrumentation resulted in 5 ± 5 mGy (1σ) spectral intensity reproducibility at the 100 mGy dose level for the seven samples analysed. Similarly, at the 1100 mGy level, spectral intensity reproducibility was found to be equivalent to 13 ± 5 mGy (1σ) for the same seven samples. Assuming linearity of dose response in the 0-1100 mGy dose range and using dose responses at 100 mGy and 1100 mGy levels, gave an overall extrapolated x intercept (dose estimate) offset of -13 ± 19 mGy (1σ).}, number={1}, journal={Radiation Protection Dosimetry}, publisher={Oxford University Press (OUP)}, author={Haskell, E.H. and Hayes, R.B. and Kenner, G.H. and Wieser, A. and Aragno, D. and Fattibene, P. and Onori, S.}, year={1999}, month={Aug}, pages={527–535} }
 @article{haskell_hayes_kenner_1999, title={An EPR Dosimetry Method For Rapid Scanning of Children Following A Radiation Accident Using Deciduous Teeth}, volume={76}, DOI={10.1097/00004032-199902000-00005}, abstractNote={Electron paramagnetic resonance dosimetry may be applied to whole deciduous teeth of children. This makes it feasible to make direct measurement of absorbed gamma ray dose in the days and weeks following a nuclear accident, particularly if used in conjunction with a public awareness program. The technique reported here requires little sample preparation and has resulted in precision of approximately 30 mGy (1 sigma) for a deciduous incisor. Under conditions for rapid screening procedures, the methodology is estimated to provide 0.5 Gy accuracy. The largest error in the process is the determination of an appropriate background native signal for subtraction from the whole tooth spectrum. The native signal is superimposed on the radiation-induced signal, and the subtraction requires knowledge of a sample's relative content of enamel and dentin along with their relative native signal intensities. Using a composite background standard, an equivalent absorbed dose of 70+/-38 mGy (1 sigma) was determined. The lower detection limit of the technique was achieved by the elimination of anisotropic effects through rotation of the sample during measurement, together with subtraction of the standard native background signal and empty tube background spectra from the sample spectra.}, number={2}, journal={Health Physics}, publisher={Ovid Technologies (Wolters Kluwer Health)}, author={Haskell, E. H. and Hayes, R. B. and Kenner, G. H.}, year={1999}, pages={137–144} }
 @article{haskell_hayes_romanyukha_barrus_kenner_1999, title={Automated Spectral Manipulation and Data Analysis for EPR Dosimetry of Teeth}, volume={84}, DOI={10.1093/oxfordjournals.rpd.a032791}, abstractNote={A method for automating the spectral manipulation and data analysis procedures for EPR dosimetry of teeth is presented. The method is shown to correlate with conventional spectral peak-to-peak values to within 10 mGy for the reconstructed doses. Paired difference t-test data show that definitive systematic differences exist but that these effects on the reconstructed dose accuracy and precision are negligible for typical applications in tooth enamel EPR dosimetry. The algorithm is written in Hypercard© script for Macintosh computers but could be -implemented on other platforms.}, number={1}, journal={Radiation Protection Dosimetry}, publisher={Oxford University Press (OUP)}, author={Haskell, E.H. and Hayes, R.B. and Romanyukha, A.A. and Barrus, J.K. and Kenner, G.H.}, year={1999}, month={Aug}, pages={521–526} }
 @article{hayes_1999, title={Electron paramagnetic resonance dosimetry: Methodology and material characterization}, volume={26}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85024820162&partnerID=MN8TOARS}, DOI={10.1118/1.598776}, abstractNote={Electron paramagnetic resonance(EPR) methodologies for radiationdosimetry are investigated using various dosimeter materials. Specifically, methodologies were developed and used which were intended to improve the accuracy and precision of EPR dosimetric techniques, including combining specimen rotation during measurement, use of an internal manganese standard, instrument stabilization techniques, and strict measurement protocols. Characterization and quantification of these improvements were performed on three specific EPR dosimeter materials. The dosimeter materials investigated were walrus teeth, human tooth enamel, and alanine dosimeters. Walrus teeth showed the least desirable properties for EPRdosimetry yielding large native signals and low radiation sensitivity. The methods for tooth enamel and alanine resulted in large improvements in precision and accuracy. The minimum detectable dose (MDD) found for alanine was approximately 30 mGy (three standard deviations from the measured zero dose value). This is a sensitivity improvement of 5 to 10 over other specialized techniques published in the literature that offer MDDs in the range of 150–300 mGy. The accuracy of the method on tooth-enamel was comparable to that typically reported in the literature although the measurement precision was increased by about 7. This improvement in measurement precision enabled a more nondestructive testing evaluation procedure to be developed (where the whole sample need not be additively irradiated in order to calibrate its radiation sensitivity). Using this virtually nondestructive evaluation procedure on numerous samples showed that the method could reconstruct the same doses to within 10 mGy of those evaluated destructively. Doses used for this assessment were in the range of 100–250 mGy.}, number={11}, journal={Med. Phys.}, publisher={American Association of Physicists in Medicine (AAPM)}, author={Hayes, Robert Bruce}, year={1999}, pages={2516} }
 @article{romanyukha_hayes_haskell_kenner_1999, title={Geographic Variations in the EPR Spectrum of Tooth Enamel}, volume={84}, DOI={10.1093/oxfordjournals.rpd.a032774}, abstractNote={The presence of stable radiation-induced radicals in the mineral component of tooth enamel allows use of this material as a biological dosemeter. Estimation of the dose absorbed in tooth enamel can be done by EPR. Generally, for the purpose of dose reconstruction, the EPR spectrum of tooth enamel is interpreted in terms of two main components. The first is a broad background signal often called the native signal centered at a g value of 2.0045. The origin of this signal is not precisely known. The second main component in the tooth enamel spectrum (g⊥ = 2.0018, g∥ = 1.9985) is purely radiation induced and can be used for retrospective dosimetry. Internal structure of the native signal and variations of its amplitude and linewidth were investigated for the samples prepared from modern teeth obtained from different geographic locations (USA and Russia). Possible reasons for the variations observed are discussed as are the potential effects of the variations on the reliability of dose estimation.}, number={1}, journal={Radiation Protection Dosimetry}, publisher={Oxford University Press (OUP)}, author={Romanyukha, A.A. and Hayes, R.B. and Haskell, E.H. and Kenner, G.H.}, year={1999}, month={Aug}, pages={445–449} }
 @article{haskell_hayes_kenner_1998, title={A High Sensitivity EPR Technique for Alanine Dosimetry}, volume={77}, DOI={10.1093/oxfordjournals.rpd.a032293}, abstractNote={Uncertainties of ±5 mGy were achieved in the measurement of alanine dosemeters using optimised EPR parameters, instrumentation, spectral manipulation and subtraction techniques. Modulation amplitude and microwave power were adjusted to combine resonances of two neighbouring alanine signals. Instrumental variations were minimised by combining and subtracting pre- and post-measurement spectra of the empty EPR tube. A spectrum of the native signal of non-dosed alanine was generated from a single batch of dosemeters and subtracted from spectra of the irradiated dosemeters, also from the same batch. Field alignment was adjusted with the use of an in-cavity Mn ++ standard. A constant rotation goniometer was used to eliminate anisotropies in the EPR tube and alanine samples. Finally, digital filters were applied to the resulting spectra.}, number={1}, journal={Radiation Protection Dosimetry}, publisher={Oxford University Press (OUP)}, author={Haskell, E.H. and Hayes, R.B. and Kenner, G.H.}, year={1998}, month={May}, pages={43–49} }
 @article{hayes_haskell_kenner_1998, title={An assessment of the Levenberg-Marquardt fitting algorithm on saturating exponential data sets}, volume={16}, number={2}, journal={Ancient TL}, author={Hayes, R.B. and Haskell, E.H. and Kenner, G.H.}, year={1998}, pages={57–62} }
 @article{hayes_kenner_haskell_1998, title={EPR Dosimetry of Pacific Walrus (Odobenus Rosmarus Divergens) Teeth}, volume={77}, DOI={10.1093/oxfordjournals.rpd.a032295}, abstractNote={The potential for EPR dosimetry using walrus tooth cementum was examined. Using standard peak to peak methods, individual measurement errors of the dosimetric signal (g 2.0018) were approximately 350 mGy (I SD). Linearity of the dose response extended up to 6 kGy for large intact specimens. The dentin was found to have a larger g=2.005 signal than the cementum and so was not investigated for linearity or sensitivity due to its expected higher organic content. A complex native signal was seen in all samples. A heat induced signal similar to that occurring in human tooth enamel was also observed. The signal was detectable at temperatures as low as 70°C. Deorganification with diethylenetriamine using the Soxhlet extraction procedure decreased the initial dosimetric signal by a factor of 10.}, number={1}, journal={Radiation Protection Dosimetry}, publisher={Oxford University Press (OUP)}, author={Hayes, R.B. and Kenner, G.H. and Haskell, E.H.}, year={1998}, month={May}, pages={55–63} }
 @article{kenner_haskell_hayes_baig_higuchi_1998, title={EPR Properties of Synthetic Apatites, Deorganified Dentine, and Enamel}, volume={62}, DOI={10.1007/s002239900457}, number={5}, journal={Calcified Tissue International}, publisher={Springer Science \mathplus Business Media}, author={Kenner, G. H. and Haskell, E. H. and Hayes, R. B. and Baig, A. and Higuchi, W. I.}, year={1998}, month={May}, pages={443–446} }
 @article{sholom_haskell_hayes_chumak_kenner_1998, title={Influence of crushing and additive irradiation procedures on EPR dosimetry of tooth enamel}, volume={29}, DOI={10.1016/s1350-4487(97)00205-9}, abstractNote={The effect of the crushing and additive dose procedures used in EPR dosimetry of enamel on EPR signals with g-factors of 2.0045 and g⊥=2.0018, g||=1.9975 was studied. Eight fractions, ranging in size from <75 μm to 2 mm, were prepared from one tooth. Two cases were investigated: crushing of a non-irradiated sample and crushing of a previously irradiated sample (6 Gy from a 60Co gamma ray source). In the non-irradiated case, the intensity of the native signal at 2.0045 increased by approximately 1.75 times as the grain size decreased from maximum to minimum. A small decrease (<8%) in radiation sensitivity (change in signal intensity per unit of irradiation) was also observed with decreasing grain size. In the irradiated samples, crushing resulted in slight variations of reconstructed doses from expected values, but the worst case (grain sizes <75 μm) showed that additional errors were less than 10%. Due to the presence of transient signals, the radiation sensitivity of enamel measured immediately after exposure is underestimated. It increases by about 15% in the first month. Based on the decomposition of the observed spectra, a new interpretation of transient signals is proposed which explains the above phenomena. Recommendations about how to use this interpretation in retrospective EPR dosimetry are given.}, number={1}, journal={Radiation Measurements}, publisher={Elsevier BV}, author={Sholom, S.V. and Haskell, E.H. and Hayes, R.B. and Chumak, V.V. and Kenner, G.H.}, year={1998}, month={Feb}, pages={105–111} }
 @article{sholom_haskell_hayes_chumak_kenner_1998, title={Properties of light induced EPR signals in enamel and their possible interference with gamma-induced signals}, volume={29}, DOI={10.1016/s1350-4487(97)00227-8}, abstractNote={Exposure of tooth enamel to natural and artificial UV light results in stable EPR signals with g-factors of 1.9985, 2.0018, 2.0045, 2.0052 and 2.0110. The first three signals correspond to the parallel and perpendicular components of the radiation induced or dosimetric signal and the native signal reported in dosimetry and dating studies. The latter two signals were found to be sensitive to both gamma-ray and sunlight exposure, however, their responses to light differed from that to radiation, giving rise to the possibility of using them as indicators of the dose-equivalent resulting from light exposure.}, number={1}, journal={Radiation Measurements}, publisher={Elsevier BV}, author={Sholom, S.V and Haskell, E.H and Hayes, R.B and Chumak, V.V and Kenner, G.H}, year={1998}, month={Feb}, pages={113–118} }
 @article{hayes_haskell_romanyukha_kenner_1998, title={Technique for increasing reproducibility in EPR dosimetry of tooth enamel}, volume={9}, DOI={10.1088/0957-0233/9/12/011}, abstractNote={Variations in several electron paramagnetic resonance (EPR) spectral parameters of importance in retrospective dosimetry of tooth enamel were measured using instrumentation and methodologies designed to maximize measurement reproducibility. Measurements were made using accessory EPR equipment that can be readily constructed with little more than a variable power supply, a geared down motor and some high-purity CaO. Spectroscopic precision is considerably enhanced due to elimination of sample anisotropies by scanning samples throughout their angular range. Frequency drifting incurred by sample reorientation and instrument/sample warm-up is effectively eliminated using an in-cavity :CaO standard. This work shows that for highly anisotropic samples, spectral characteristic parameters (peak-to-peak amplitudes, signal component widths and positions) are reproduced with equal or comparable precision to the case where standard EPR configurations are used while measuring approximately isotropic samples.}, number={12}, journal={Meas. Sci. Technol.}, publisher={IOP Publishing}, author={Hayes, R B and Haskell, E H and Romanyukha, A A and Kenner, G H}, year={1998}, pages={1994–2006} }
 @article{hayes_haskell_kenner_1997, title={A mathematical approach to optimal selection of dose values in the additive dose method of EPR dosimetry}, volume={27}, DOI={10.1016/s1350-4487(96)00117-5}, abstractNote={Additive dose methods commonly used in electron paramagnetic resonance (EPR) dosimetry are time consuming and labor intensive. We have developed a mathematical approach for determining optimal spacing of applied doses and the number of spectra which should be taken at each dose level. Expected uncertainties in the data points are assumed to be normally distributed with a fixed standard deviation and the linearity of the dose response is also assumed. The optimum spacing and number of points necessary for minimal error can be estimated as can the likely error in the resulting dose estimate. When low doses are being estimated for enamel samples, the optimal spacing is shown to be a concentration of points near the zero dose value with fewer spectra taken at a single high dose value within the range of known linearity. Optimization of the analytical process results in increased accuracy and sample throughput.}, number={2}, journal={Radiation Measurements}, publisher={Elsevier BV}, author={Hayes, R.B. and Haskell, E.H. and Kenner, G.H.}, year={1997}, month={Apr}, pages={315–323} }
 @article{haskell_kenner_hayes_sholom_chumak_1997, title={An EPR intercomparison using teeth irradiated prior to crushing}, volume={27}, DOI={10.1016/s1350-4487(96)00131-x}, abstractNote={An intercomparison of methods used for EPR dosimetry of enamel was made by the Center for Applied Dosimetry at the University of Utah and the Scientific Center for Radiation Medicine in the Ukraine (SCRM). The Utah group used the differential microwave power technique while the Ukrainian group employed a system of chemical preparation combined with a technique of subtraction of standard background signals. Because of time constraints, the results were reported before each laboratory had performed detailed background analyses. These results showed that both methods were in good agreement with the applied dose. Subsequent to this, the Utah group continued work on refining the differential power technique while SCRM investigated the differences between the inner and outer portions of the teeth. It was determined that the contribution of dental X-rays to the total dose was between 20 and 140 mGy.}, number={2}, journal={Radiation Measurements}, publisher={Elsevier BV}, author={Haskell, E. and Kenner, G. and Hayes, R. and Sholom, S. and Chumak, V.}, year={1997}, month={Apr}, pages={419–424} }
 @book{haskell_kenner_hayes_chumak_shalom_1997, title={EPR dosimetry teeth in past and future accidents: A prospective look at a retrospective method}, DOI={10.2172/446328}, abstractNote={Accurate assessments of doses received by individuals exposed to radiation from nuclear accidents and incidents such as those at Hiroshima and Nagasaki, the Nevada test site, Cheliabinsk and Mayak are required for epidemiological studies seeking to establish relationships between radiation dose and health effects. One method of retrospective dosimetry which allows for measurement of cumulative gamma ray doses received by exposed individuals is electron paramagnetic resonance spectroscopy (EPR) of tooth enamel. Tooth enamel stores and retains, indefinitely, information on absorbed radiation dose. And teeth are available in every population as a result of dental extraction for medical reasons including periodontal disease and impacted wisdom teeth. In the case of children, deciduous teeth, which are shed between the ages of 7 and 13, can be a very important dosimetric source if documented collection is implemented shortly following an accident.}, institution={Office of Scientific and Technical Information (OSTI)}, author={Haskell, E. and Kenner, G. and Hayes, R. and Chumak, V. and Shalom, S.}, year={1997}, month={Mar} }
 @article{haskell_hayes_kenner_sholom_chumak_1997, title={Electron Paramagnetic Resonance Techniques and Space Biodosimetry}, volume={148}, ISSN={0033-7587}, url={http://dx.doi.org/10.2307/3579717}, DOI={10.2307/3579717}, abstractNote={This paper was presented at a workshop addressing the potential of biodosimetry techniques for use in the interplanetary space program. Some of the concerns for adequate dosimetry in space include: (1) a dosimeter that provides a permanent record of the cumulative dose and can be read independently on return to Earth; (2) a dosimeter which cannot be lost, forgotten or inadvertently removed by an individual; and (3) appropriate assessments of radiation exposures that pose an acute health risk and could jeopardize the success of an interplanetary mission. Tooth enamel is a permanent, stable biological dosimeter showing great promise in retrospective dosimetry of radiation accidents. With a proper technique, the minimum detectable dose can be in the range of tens of milligrays in extracted, prepared teeth. In addition to transient accidental doses, the cumulative dose from chronic low-level exposures (which individually may be below reportable limits) is recorded in the enamel of teeth. While many teeth remain with an individual over all or most of a lifetime, one or more are often removed due to dental problems and provide an opportunity to make dosimeteric measurements. The collection and analysis of extracted teeth in later life allows measurement of cumulative lifetime dose using the high-sensitivity techniques described in this paper. The goal of a lightweight, high-sensitivity, in vivo EPR spectrometer has not yet been realized, but its benefit to all aspects of retrospective dosimetry, terrestrial or otherwise, would be great. This paper reviews the current status of EPR dosimetry of teeth as applied to retrospective measurements of accidental exposures and outlines future research directions which will further reduce the limits of detection.}, number={5}, journal={Radiation Research}, publisher={JSTOR}, author={Haskell, E. H. and Hayes, R. B. and Kenner, G. H. and Sholom, S. V. and Chumak, V. I.}, year={1997}, month={Nov}, pages={S51} }
 @article{haskell_hayes_kenner_1997, title={Improved accuracy of EPR dosimetry using a constant rotation goniometer}, volume={27}, DOI={10.1016/s1350-4487(96)00107-2}, abstractNote={Grains of sufficiently small diameter will theoretically result in an isotropic EPR response which is independent of sample orientation. In practice, use of such small grains may present problems of altered sensitivity and newly induced paramagnetic centers. Additionally, the effect of anisotropy is increased with increasing microwave power. This places limits on the effectiveness of the differential power method which allows determination of cumulative dose without the need for a zero background signal. The use of a constant rotation goniometer reduces the effect of anisotropy, making measurements at all microwave powers, and particularly the higher powers, significantly more accurate. Since the organic and the mineralized components of the EPR signal are both effected by anisotropy, this procedure may well result in reduced limits of detection.}, number={2}, journal={Radiation Measurements}, publisher={Elsevier BV}, author={Haskell, E.H. and Hayes, R.B. and Kenner, G.H.}, year={1997}, month={Apr}, pages={325–329} }
 @book{haskell_hayes_kenner_1996, title={EPR dosimetry of whole deciduous tooth using a constant rotation goniometer and background subtraction with a dentine standard}, DOI={10.2172/483334}, abstractNote={We report here a rapid method of electron paramagnetic resonance (EPR) dosimetry of dental enamel which will allow screening of whole deciduous teeth of children following a nuclear accident. The technique requires virtually no sample preparation and is capable of measuring doses of less than 100 mGy. Teeth may be scanned for threshold dose levels without the need for added calibration doses and those of particular interest may be more accurately examined using the additive dose method. The success of the technique lies in the elimination of anisotropic effects by rotation of spectra from the empty cavity and a standard background tooth. Normalization using in- cavity Mn++ standards is also employed.}, institution={Office of Scientific and Technical Information (OSTI)}, author={Haskell, E.H. and Hayes, R.B. and Kenner, G.H.}, year={1996}, month={Jan} }
 @book{shalom_chumak_haskell_hayes_kenner_1996, title={Influence of crushing and additive irradiation procedures on EPR dosimetry of tooth enamel}, DOI={10.2172/454027}, abstractNote={The effect of the crushing and additive dose procedures used in EPR dosimetry of enamel was studied on the signals with g-factors of 2. 0045 and g, = 2.0018, g. = 1.9975. Eight fractions, ranging in size from <75 micrometers to 2 mm, were prepared from one tooth. Two cases were investigated: crushing of a non-irradiated sample and of a sample previously irradiated (6 Gy from `Co gamma ray source). In the non-irradiated study, the intensity of the native signal at 2.0045 in by circa 1.75 times as the grain size decreased from maximum to minimum. A small in radiation sensitivity (< 8%) was also observed with decreasing grain size. In the irradiated samples, crushing resulted in slight variations of reconstructed doses from expected values, but the worst possible case (grain sizes < 75 micron) showed that additional errors were less than 10%. The radiation sensitivity of enamel measured immediately after exposure is underestimated. It increases by about 15% in the first month. Based on the decomposition of the observed spectra, a new interpretation of transient signals 1108 is proposed which explains the above phenomena. Recommendations about how to use this interpretation in retrospective EPR dosimetry are given.}, institution={Office of Scientific and Technical Information (OSTI)}, author={Shalom, S.V. and Chumak, V.V. and Haskell, E.H. and Hayes, R.B. and Kenner, G.H.}, year={1996}, month={Jan} }
 @article{haskell_hayes_kenner_1996, title={Preparation-induced errors in EPR dosimetry of enamel: Pre- and post-crushing sensitivity}, volume={47}, DOI={10.1016/s0969-8043(96)00163-7}, abstractNote={Polyakov et al. (1995) showed errors in dose estimation as a function of grain size for enamel grains given beta irradiation after crushing. We tested the effect of gamma irradiation applied to the specimens before and after crushing. We confirmed Polyakov's observations and found that post-crushing irradiation altered the slope of the dose-response curve of the hydroxyapatite signal and produced a grain-size-dependent offset. No changes in the slope of the dose-response curve were seen in enamel caps irradiated whole before crushing.}, number={11-12}, journal={Applied Radiation and Isotopes}, publisher={Elsevier BV}, author={Haskell, E.H. and Hayes, R.B. and Kenner, G.H.}, year={1996}, month={Nov}, pages={1305–1310} }
 @book{haskell_hayes_kenner_1996, title={Preparation-induced errors in EPR dosimetry of enamel: pre- and post-crushing sensitivity}, DOI={10.2172/483333}, abstractNote={Errors in dose estimation as a function of grain size for tooth enamel has been previously shown for beta irradiation after crushing. We tested the effect of gamma radiation applied to specimens before and after crushing. We extend the previous work in that we found that post-crushing irradiation altered the slope of the dose-response curve of the hydroxyapatite signal and produced a grain-size dependent offset. No changes in the slope of the dose-response curve were seen in enamel caps irradiated before crushing.}, institution={Office of Scientific and Technical Information (OSTI)}, author={Haskell, E.H. and Hayes, R.B. and Kenner, G.H.}, year={1996}, month={Jan} }
 @book{shalom_chumak_haskell_hayes_kenner_1996, title={Properties of light induced EPR signals in enamel and their possible interference with gamma-induced signals}, DOI={10.2172/321858}, abstractNote={Exposure of enamel to UV light (sunlight and artificial) results in EPR signals with g-factors of 2.0018 (perpendicular),1.9975 (parallel), 2.0045, 20052, and 2.0083. The first two signals correspond to the components of the radiation induced signal and the third signal corresponds to the native signal reported in dosimetry and dating studies. The remaining signals were found to be stable and sensitive to both gamma and sunlight exposure. Their sensitivity response to light and radiation was considerably different which gives rise to the possibility that the g=2.0052 and g=2.0083 signals might be used as indicators of the dose resulting from light exposure.}, institution={Office of Scientific and Technical Information (OSTI)}, author={Shalom, S.V. and Chumak, V.V. and Haskell, E.H. and Hayes, R.B. and Kenner, G.H.}, year={1996}, month={Jan} }
 @article{chumak_bailiff_baran_bugai_dubovsky_fedosov_finin_haskell_hayes_ivannikov_et al._1996, title={The first international intercomparison of EPR-dosimetry with teeth: First results}, volume={47}, ISSN={0969-8043}, url={http://dx.doi.org/10.1016/s0969-8043(96)00231-x}, DOI={10.1016/s0969-8043(96)00231-x}, abstractNote={Intercomparison of EPR-dosimetric techniques using tooth enamel had been performed in order to check whether the results produced by different laboratories are consistent and accurate. Participants were supposed to evaluate doses applied to pulverized enamel samples, using routine techniques from their laboratories. The intercomparison has demonstrated a great variety of methods used for dose reconstruction. Peculiarities of experimental approaches are discussed systematically in terms of procedure for recording the EPR-spectra, determination of the amplitude of the radiation induced signal, determination of the dose, and error propagation.}, number={11-12}, journal={Applied Radiation and Isotopes}, publisher={Elsevier BV}, author={Chumak, V. and Bailiff, I. and Baran, N. and Bugai, A. and Dubovsky, S. and Fedosov, I. and Finin, V. and Haskell, E. and Hayes, R. and Ivannikov, A. and et al.}, year={1996}, month={Nov}, pages={1281–1286} }
 @article{polyakov_haskell_kenner_huett_hayes_1995, title={Effect of mechanically induced background signal on EPR dosimetry of tooth enamel}, volume={24}, DOI={10.1016/1350-4487(95)00124-w}, abstractNote={The effect of the mechanically induced background ESR signal whose Lande factor is g = 2.0038, width = 0.791 mT, on absorbed dose estimation using the additive method was studied. The intensity and width of this signal increases with decreasing grain size. It was found to be thermally stable and sensitive to 90Sr radiation. The latter phenomenon should lead to its increasing contribution to the radiation-induced hydroxyapatite signal at g⊥ = 2.0018 at irradiation with higher doses. However, it was found that the interference between mechanically induced and the hydroxyapatite signals may be interpreted as either ‘negative’ for larger grain size or ‘positive’ for finer grain size. This feature in turn leads to under and overestimation of the hydroxyapatite signal, respectively, and is apparently caused by the inverse relationship between the signal width and grain size. Enamel samples were irradiated with 44, 88, 220, 440, 660 and 880 mGy from a 137Cs gamma ray source. It was determined that 220 mGy was the lowest absorbed dose that could be reliably detected, while doses as low as 44 mGy could tentatively be identified.}, number={3}, journal={Radiation Measurements}, publisher={Elsevier BV}, author={Polyakov, V. and Haskell, E. and Kenner, G. and Huett, G. and Hayes, R.}, year={1995}, month={Jul}, pages={249–254} }
 @article{haskell_kenner_hayes_1995, title={Electron Paramagnetic Resonance Dosimetry of Dentine Following Removal of Organic Material}, volume={68}, ISSN={0017-9078}, url={http://dx.doi.org/10.1097/00004032-199504000-00017}, DOI={10.1097/00004032-199504000-00017}, abstractNote={The feasibility of using dentine from surgically extracted human teeth as in vivo dosimeters was investigated. The organic fraction of human dentine was removed by Soxhlet extraction with diethylenetriamine. The specimens were then crushed and 75 to 250 microns granules were given doses of gamma radiation ranging from 50 mGy to 8 Gy. Following irradiation, electron paramagnetic resonance spectra were collected. Signals were detected with Lande factors of g = 2.0018, line width = 0.903 mT; and g = 1.9961, line width = 0.444 mT. These signals have both been reported for hydroxyapatite of bone and enamel. Several other signals were also seen but not characterized. It was concluded that doses of 500 mGy or less may be resolved with prior removal of the organic component of dentine.}, number={4}, journal={Health Physics}, publisher={Ovid Technologies (Wolters Kluwer Health)}, author={Haskell, E. H. and Kenner, G. H. and Hayes, R. B.}, year={1995}, month={Apr}, pages={579–584} }