TY - CONF TI - Mortality of Insects on the Surface of Plants using an Atmospheric Pressure Plasma Discharge AU - Bures, Brian L. AU - Donohue, Kevin V. AU - Long, Shengyou AU - Bourham, Mohamed A. AU - Roe, R.Michael T2 - Beltwide Cotton Conference C2 - 2004/// C3 - Proceedings of the Beltwide Cotton Conference CY - San Antonio, TX DA - 2004/// PY - 2004/1/6/ ER - TY - JOUR TI - Area X-Ray Source for Industrial, Clinical and Screening Applications AU - Kim, Chang H. AU - Doster, J.Michael AU - Bourham, Mohamed A. T2 - ANS Transactions DA - 2004/11// PY - 2004/11// VL - 91 SP - 686–687 ER - TY - RPRT TI - Static Charges and Arc Channels Effect on Initiation of Chemical Reactions in Energetic Materials AU - Bourham, M. A3 - US Navy Office of Naval Research DA - 2004/3// PY - 2004/3// M3 - Final Technical Report PB - US Navy Office of Naval Research ER - TY - JOUR TI - Editorial AU - Dunn, William AU - Fernández, Jorge E. AU - Gardner, Robin P. AU - Tartari, Agostino T2 - Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms DA - 2004/1// PY - 2004/1// DO - 10.1016/S0168-583X(03)01525-8 VL - 213 SP - vii-viii SN - 0168-583X UR - http://dx.doi.org/10.1016/S0168-583X(03)01525-8 ER - TY - JOUR TI - Generalized photon skyshine calculations AU - Hayes, RB T2 - Radiation Protection Dosimetry AB - 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. DA - 2004/// PY - 2004/// DO - 10.1093/rpd/nch342 VL - 111 IS - 3 SP - 251–256 ER - TY - JOUR TI - Impurities in CdZnTe crystal grown by vertical Bridgman method AU - Li, Guoqiang AU - Jie, Wanqi AU - Wang, Tao AU - Yang, Ge T2 - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment AB - The impurity segregation in CdZnTe grown by vertical Bridgman method and its corresponding effects on the crystal optical and electrical properties have been studied in detail. Inductively coupled plasma mass spectrometry reveals that impurities Al and Ga with segregation coefficient larger than one centralize in the first-to-freeze portion of the ingot, while impurities Li, Na, Mn, and Cu with segregation coefficient less than one enrich in the last-to-freeze portion of the ingot. At the same time, all impurities enrich in the grain boundaries. Hall measurement indicates that there exists an approximate linear monotonously increasing relationship between the free-carrier density and the sum of all the impurities concentration, which leads to an increase in the infrared transmission with the increase of wave number within the impurity enriching portions caused by the free carrier absorption. It is also found that the resistivity decreases with the concentration of Li, Na, and Cu, but increases with the concentration of Al, Mn, and Ga. An annealing processing is adopted to extract the impurities and therefore improve the crystal properties. DA - 2004/12// PY - 2004/12// DO - 10.1016/J.NIMA.2004.06.135 VL - 534 IS - 3 SP - 511-517 J2 - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment LA - en OP - SN - 0168-9002 UR - http://dx.doi.org/10.1016/J.NIMA.2004.06.135 DB - Crossref KW - segregation KW - IR transmission KW - free-carrier absorption KW - annealing KW - CdZnTe ER - TY - JOUR TI - Behaviors of impurities in Cd0.85Zn0.15Te crystals grown by vertical Bridgman method AU - Li, Guoqiang AU - Jie, Wanqi AU - Yang, Ge AU - Wang, Tao T2 - Materials Science and Engineering: B AB - The distribution of impurities Li, Na, Mg, Al, S, Cl, K, Cu, In, Ga and Ag in Cd0.85Zn0.15Te crystal ingots grown by vertical Bridgman method has been investigated using the inductively coupled plasma mass spectrometry (ICP/MS). It is found that the segregation coefficients of Al, S, In and Ga are larger than unit, which leads to their enrichment in the first-to-freeze portion of ingots, while the segregation coefficients of Li, Na, Mg, Cl, K, Cu and Ag are less than unit, which leads to their enrichment in the last-to-freeze portion of ingots. Resistivity measurements reveal that Mg, Al, S, Cl, In and Ga are positive to increase the resistivity of Cd0.85Zn0.15Te, while Li, Na, K, Cu, and Ag are negative. Infrared (IR) transmission measurements and Hall measurements indicate that the free carrier absorption within the both impurity enriching portions decreases IR transmission and causes a decrease in IR transmission with the decrease of wavenumber. After an annealing processing, the concentration of all the impurities is highly reduced and the crystal properties are remarkably improved. DA - 2004/10// PY - 2004/10// DO - 10.1016/j.mseb.2004.05.006 VL - 113 IS - 1 SP - 7-12 J2 - Materials Science and Engineering: B LA - en OP - SN - 0921-5107 UR - http://dx.doi.org/10.1016/j.mseb.2004.05.006 DB - Crossref KW - segregation KW - IR transmission KW - free-carrier absorption KW - annealing KW - Cd1-xZnxTe ER - TY - JOUR TI - Growth of In doped CdZnTe by vertical Bridgman method and the effect of In on the crystal properties AU - Li, Guoqiang AU - Jie, Wanqi AU - Gu, Zhi AU - Yang, Ge AU - Wang, Tao AU - Zhang, Jijun T2 - Journal of Crystal Growth AB - An Indium (In) doped Cd0.9Zn0.1Te (CdZnTe:In) ingot was grown by vertical Bridgman method. The distribution of In in the ingot was analyzed. It was evaluated that the segregation coefficient of In in CdZnTe during the growth was 1.3, which caused a higher In concentration in the initial part of CdZnTe:In ingot and a lower In concentration in the final part. In was also enriched at the grain boundaries but homogeneously distributed inside the grains in the as-grown crystal. Photoluminescence spectra indicated that In had two states existing in the CdZnTe:In ingot. One was interstitial neutral In and the other was substitutional ion In+. The two states led to the two donor levels at 0.12 and 0.04 eV in CdZnTe:In band construction, respectively. IR transmission measurements exhibited that CdZnTe:In was almost opaque to IR emission when the wavenumber was larger than 1000 cm−1, then was 24% transparent when the wavenumber was decreased to lower than 1000 cm−1. This phenomenon also confirmed the existence of the donor level of 0.12 eV demonstrated by the PL spectra. Resistivity measurements revealed that CdZnTe:In obtained three orders higher resistivity than CdZnTe. It meant that doping of In into CdZnTe could improve the crystal properties. DA - 2004/4// PY - 2004/4// DO - 10.1016/j.jcrysgro.2003.12.079 VL - 265 IS - 1-2 SP - 159-164 J2 - Journal of Crystal Growth LA - en OP - SN - 0022-0248 UR - http://dx.doi.org/10.1016/j.jcrysgro.2003.12.079 DB - Crossref KW - defects KW - doping KW - segregation KW - Bridgman technique KW - semiconducting II-VI materials ER - TY - JOUR TI - Helios, current coupling collision probability method, applied for solving the NEA C5G7 MOX benchmark AU - Ivanov, Boyan D. AU - Ivanov, Kostadin N. AU - Stamm'ler, Rudi J.J. T2 - Progress in Nuclear Energy AB - As part of an effort to test the ability of current transport codes to treat reactor core problems without spatial homogenization, the lattice code HELIOS was employed to perform criticality calculations. The test consists in seven-group calculations of the C5 MOX fuel assembly problem specified by Cavarec et. al. [1]. This problem, known as C5G7 MOX Benchmark, is described in the Benchmark Specification [2] and comprises two cases — two and three-dimensional geometry. There are four fuel assemblies — two with MOX fuel, the other two with UO2 fuel. Each fuel assembly is made up of a 17×17 lattice of square fuel-pin cells. Fuel pin compositions are specified in the Benchmark Specification, which also provides seven-group transport-corrected isotropic scattering cross-sections for U02, the three MOX enrichments, the guide tubes, the fission chamber and the moderator. This paper preset is the methodology employed in solving the C5G7 MOX Fuel Assembly Problem using the transport code HELIOS. DA - 2004/1// PY - 2004/1// DO - 10.1016/j.pnucene.2004.09.004 VL - 45 IS - 2-4 SP - 119-124 J2 - Progress in Nuclear Energy LA - en OP - SN - 0149-1970 UR - http://dx.doi.org/10.1016/j.pnucene.2004.09.004 DB - Crossref KW - HELIOS KW - deterministic KW - transport KW - MOX ER - TY - JOUR TI - Minimizing the gamma radiation effects to spent fuel pool walls AU - Tippayakul, Chanatip AU - Levine, Samuel AU - Ivanov, Kostadin N. AU - Mahgerefteh, Moussa T2 - Annals of Nuclear Energy AB - This paper presents the study of the gamma exposure to the spent fuel pool walls from spent fuel assemblies. The Monte Carlo code, MCNP4C, was used to model and analyze the spent fuel pool walls. In addition, the gamma source from the spent fuel assembly was modeled by the isotope generation and depletion code, ORIGEN2.2. Both PWR (TMI-I) and BWR (PB-2) spent fuel pool models were investigated. The primary objective of the study was to determine the arrangement of the spent fuel assemblies to minimize the gamma radiation to the spent fuel pool walls. Different cases of spent fuel assembly configurations in the spent fuel pool were studied. The study results show the amount of gamma radiation deposited on each section of the spent fuel pool walls. Finally, the spent fuel assembly with axial peaking factor was also studied. DA - 2004/3// PY - 2004/3// DO - 10.1016/j.anucene.2003.09.006 VL - 31 IS - 5 SP - 459-480 J2 - Annals of Nuclear Energy LA - en OP - SN - 0306-4549 UR - http://dx.doi.org/10.1016/j.anucene.2003.09.006 DB - Crossref ER - TY - JOUR TI - Development of the VVER core loading optimization system AU - Guler, C. AU - Levine, S. AU - Ivanov, K. AU - Svarny, J. AU - Krysl, V. AU - Mikolas, P. AU - Sustek, J. T2 - Annals of Nuclear Energy AB - The optimization procedures previously applied to Western type PWRs are being used for the first time to optimize the VVER 440 nuclear power plant (NPP)—Dukovany, and VVER 1000—NPP Temelin in the Czech Republic. The objective of the calculation is to minimize fuel cost while preserving all the safety constraints and margins. Optimization with burnable poisons (BP) is simplified by reloading the core in two steps; first, by optimum fuel placement using the Haling Power Distribution (HPD), and second, by optimum placement of burnable poisons to meet the safety constraints. This two-step single cycle optimization method can be extended to the multiple cycle level. Application to the VVER reactors involves applying a hexagonal geometry core analysis model. A program has been initiated to develop a similar multi-cycle optimization system for the VVER reactors between the Penn State University and SKODA in the Czech Republic. This research has been successful in developing loading patterns for cycles 2–4 of the Temelin NPP. The package, which was developed during this research, can be applied to any VVER reactors to optimize the core loading. DA - 2004/5// PY - 2004/5// DO - 10.1016/j.anucene.2003.09.005 VL - 31 IS - 7 SP - 747-772 J2 - Annals of Nuclear Energy LA - en OP - SN - 0306-4549 UR - http://dx.doi.org/10.1016/j.anucene.2003.09.005 DB - Crossref ER - TY - JOUR TI - NMIS plus gamma spectroscopy for attributes of HEU, PU and HE detection AU - Mihalczo, J.T. AU - Mattingly, J.K. AU - Neal, J.S. AU - Mullens, J.A. T2 - Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms AB - A combined nuclear materials identification system–gamma ray spectrometry system can be used passively to obtain the following attributes of Pu: presence, fissile mass, 240/239 ratio and metal versus oxide. This system can also be used with a small, portable, DT neutron generator to measure the attributes of highly enriched uranium (HEU): presence, fissile mass, enrichment, metal versus oxide; and detect the presence of high explosives (HE). For the passive system, time-dependent coincidence distributions can be used for the presence, fissile mass, metal versus oxide for Pu, 240/239 ratio, and gamma ray spectrometry can also be used for 240/239 ratio and presence, allowing presence and 240/239 ratio to be confirmed by two methods. For the active system with a DT neutron generator, all relevant attributes for both Pu and HEU can be determined from various features of the time-dependent coincidence distribution measurements. Active gamma ray spectrometry would determine the presence of HE. The various features of time-dependent coincidence distributions and gamma ray spectrometry that determine these attributes are discussed with some examples from previous determinations. DA - 2004/1// PY - 2004/1// DO - 10.1016/S0168-583X(03)01651-3 VL - 213 SP - 378-384 J2 - Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms LA - en OP - SN - 0168-583X UR - http://dx.doi.org/10.1016/S0168-583X(03)01651-3 DB - Crossref ER - TY - JOUR TI - Dort solutions to the two-dimensional C5G7MOXbenchmark problem AU - Azmy, Yousry Y. AU - Gehin, Jess C. AU - Orsi, Roberto T2 - Progress in Nuclear Energy AB - Abstract We present a comprehensive study of the solution error for the C5G7MOXBenchmark problem using the two-dimensional transport code DORT. We set a stringent criterion that a successful solution to the benchmark exercise must satisfy, namely that at least for some of the benchmark quantities convergence to the reference solution with computational model refinement must be demonstrated. In the present exercise this amounts to examining the evolution of the DORT solution, e.g. the multiplication factor, with increasing angular quadrature order, decreasing computational cell size, and tighter representation of the curved rod-moderator interface for all circular rods in the core model. In addition we explored the effect of angular quadrature type, comparing solution accuracy for the fully symmetric and the Square Legendre-Chebychev quadratures establishing superiority of the latter. We establish the high quality of DORT's solution to this benchmark exercise by demonstrating that the multiplication factor asymptotically approaches the reference solution as stated in our self-imposed success criterion. High accuracy of the pin power distribution is also attained, however, convergence to the reference values is not realized. We conjecture that this is due to the lack of error information in the reference values. Our results also illustrate DORT's high accuracy on reasonable meshes and quadrature orders, as well as the sufficiency of a crude, square, geometric approximation of the rod-moderator interface to achieve high accuracy. DA - 2004/1// PY - 2004/1// DO - 10.1016/j.pnueene.2004.09.011 VL - 45 IS - 2-4 SP - 215-231 J2 - Progress in Nuclear Energy LA - en OP - SN - 0149-1970 UR - http://dx.doi.org/10.1016/j.pnueene.2004.09.011 DB - Crossref KW - DORT KW - MOX KW - discrete-ordinates KW - benchmark KW - accuracy ER - TY - JOUR TI - Short-term rupture studies of Zircaloy-4 and Nb-modified Zircaloy-4 tubing using closed-end internal pressurization AU - Zhou, Y AU - Devarajan, B AU - Murty, K.L T2 - Nuclear Engineering and Design AB - Burst rupture properties of Zircaloy-4 and Nb-Modified Zircaloy-4 are investigated at temperatures ranging from 638 to 843 K by internal pressurization of closed-end tubing samples. Various pressurization levels were imposed and rupture times were noted. The data enabled an evaluation of Larson–Miller parameter and the present experimental results on Zircaloy-4 were in excellent agreement with those reported in the literature. The effect of 1% Nb addition to Zircaloy-4 was studied since these materials are now known to resist long-time corrosion in water reactors and are thus considered for high burn-up applications. Negligible differences were noted in the rupture characteristics between the standard Zircaloy-4 and Nb-added Zircaloy-4. In addition, a limited amount of testing was performed to characterize the hoop creep behavior of these materials using a creep tester with hoop strain monitored in situ by a Laser telemetric extensometer. Both the alloys followed an exponential stress variation of the creep-rate at high (>10−3E, E is the elastic modulus) stresses. At very low stresses, viscous creep was noted identifiable with Coble creep corresponding to small grain sized materials. DA - 2004/3// PY - 2004/3// DO - 10.1016/j.nucengdes.2003.06.013 VL - 228 IS - 1-3 SP - 3-13 J2 - Nuclear Engineering and Design LA - en OP - SN - 0029-5493 UR - http://dx.doi.org/10.1016/j.nucengdes.2003.06.013 DB - Crossref ER - TY - CONF TI - Two-phase natural circulation flow in AP-1000 in-vessel retention-related ULPU-V facility experiments AU - Dinh, T.N. AU - Tu, J.P. AU - Theofanous, T.G. C2 - 2004/// C3 - Proceedings of the 2004 International Congress on Advances in Nuclear Power Plants, ICAPP'04 DA - 2004/// SP - 928-938 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-14844322005&partnerID=MN8TOARS ER - TY - JOUR TI - The Characteristics-Based Matching (CBM) method for compressible flow with moving boundaries and interfaces AU - Nourgaliev, R.R. AU - Dinh, T.N. AU - Theofanous, T.G. T2 - Journal of Fluids Engineering, Transactions of the ASME AB - Recently, Eulerian methods for capturing interfaces in multi-fluid problems become increasingly popular. While these methods can effectively handle significant deformations of interface, the treatment of the boundary conditions in certain classes of compressible flows are known to produce nonphysical oscillations due to the radical change in equation of state across the material interface. One promising recent development to overcome these problems is the Ghost Fluid Method (GFM). The present study initiates a new methodology for boundary condition capturing in multifluid compressible flows. The method, named Characteristics-Based Matching (CBM), capitalizes on recent developments of the level set method and related techniques, i.e., PDE-based re-initialization and extrapolation, and the Ghost Fluid Method (GFM). Specifically, the CBM utilizes the level set function to capture interface position and a GFM-like strategy to tag computational nodes. In difference to the GFM method, which employs a boundary condition capturing in primitive variables, the CBM method implements boundary conditions based on a characteristic decomposition in the direction normal to the boundary. In this way overspecification of boundary conditions is avoided and we believe so will be spurious oscillations. In this paper, we treat (moving or stationary) fluid-solid interfaces and present numerical results for a select set of test cases. Extension to fluid-fluid interfaces will be presented in a subsequent paper. DA - 2004/// PY - 2004/// DO - 10.1115/1.1778713 VL - 126 IS - 4 SP - 586-604 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-11144306362&partnerID=MN8TOARS ER - TY - JOUR TI - Aerobreakup in rarefied supersonic gas flows AU - Theofanous, T.G. AU - Li, G.J. AU - Dinh, T.N. T2 - Journal of Fluids Engineering, Transactions of the ASME AB - We present new experimental results on the interfacial instabilities and breakup of Newtonian liquid drops suddenly exposed to rarefied, high-speed (Mach 3) air flows. The experimental approach allows for the first time detailed observation of interfacial phenomena and mixing throughout the breakup cycle over a wide range of Weber numbers. Key findings are that Rayleigh-Taylor instability alone is the active mechanism for freestream Weber numbers as low as 28 for low viscosity liquids and that stripping rather than piercing is the asymptotic regime as We→∞. This and other detailed visual evidence over 26<We<2,600 are uniquely suitable for testing Computational Fluid Dynamics (CFD) simulations on the way to basic understanding of aerobreakup over a broad range of conditions. DA - 2004/// PY - 2004/// DO - 10.1115/1.1777234 VL - 126 IS - 4 SP - 516-527 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-11144311824&partnerID=MN8TOARS ER - TY - CONF TI - Rayleigh-Bénard natural convection heat transfer: Pattern formation, complexity and predictability AU - Dinh, T.N. AU - Yang, Y.Z. AU - Tu, J.P. AU - Nourgaliev, R.R. AU - Theofanous, T.G. C2 - 2004/// C3 - Proceedings of the 2004 International Congress on Advances in Nuclear Power Plants, ICAPP'04 DA - 2004/// SP - 1342-1352 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-14844334669&partnerID=MN8TOARS ER - TY - CONF TI - Particle-to-particle long range interaction and drag in supersonic flows AU - Li, G.J. AU - Nourgaliev, R.R. AU - Dinh, T.N. AU - Theofanous, T.G. C2 - 2004/// C3 - AIAA Paper DA - 2004/// DO - 10.2514/6.2004-1064 SP - 6604-6614 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-2942746723&partnerID=MN8TOARS ER - TY - JOUR TI - A pseudocompressibility method for the numerical simulation of incompressible multifluid flows AU - Nourgaliev, R.R. AU - Dinh, T.N. AU - Theofanous, T.G. T2 - International Journal of Multiphase Flow AB - This paper presents an explicit characteristics-based, conservative, finite-difference method for the simulation of incompressible multiphase flows. The method is based on the artificial compressibility concept, extended to variable-density, and uses a time stretching procedure to relieve the acoustic constrain. We take advantage of the algorithmic simplicity and hyperbolicity provided by the artificial compressibility to develop a flow solver that is numerically robust, accurate and effective for massively parallel computations of incompressible multifluid flows. The resulting method, named Numerical Acoustic Relaxation or NAR, is a combination of the AC concept with the Level Set method for interface-capturing and the Ghost-Fluid method to compute flows with multiple, arbitrary density variation, free or stationary interfaces. In this paper we demonstrate convergence and accuracy of the solver by computing such standard test problems as the “Lid-Driven Cavity” and “Doubly Periodic Shear Layer”. Competitiveness with approximate projection, vorticity stream function, pseudospectral, and Lattice Boltzmann Equation is also discussed. In addition, we demonstrate the interface-capturing features of NAR by means of the “simple” “Rayleigh–Taylor” and “Water Column Collapse” problems. DA - 2004/// PY - 2004/// DO - 10.1016/j.ijmultiphaseflow.2004.03.010 VL - 30 IS - 7-8 SPEC. ISS. SP - 901-937 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-3242720707&partnerID=MN8TOARS KW - incompressible flow KW - artificial compressibility KW - pseudocompressibility method KW - numerical acoustic relaxation KW - characteristics-based treatment KW - level set KW - ghost fluid KW - multifluid flow ER - TY - CONF TI - A numerical study of the shape effect on drag in supersonic low reynolds number (rarefied) flows AU - Sushchikh, S.Yu. AU - Dinh, T.N. AU - Theofanous, T.G. AB - The present numerical study is motivated by the analysis of pressure and shear forces that a rarefled supersonic ∞ow exerts on a drop and acts to deform the drop. We use a high-order accurate Cartesian-grid-based numerical scheme and an advanced method for boundary condition treatment to solve the Navier-Stokes equations for high-speed ∞ows around circular and elliptical bodies with difierent aspect ratios that represent difierent stages of the drop deformation. The calculation results depict a strong efiect of the aspect ratio on drag, while predict weaker dependencies of drag on Reynolds and Mach number over the range examined. With the decrease of aspect ratio, the pressure drag increases while the shear drag decreases. Finally, we show that for a flxed Weber number, the corresponding variation of Mach and Reynolds numbers renders minor changes in pressure drag but signiflcantly alter the shear drag. C2 - 2004/// C3 - AIAA Paper DA - 2004/// DO - 10.2514/6.2004-1063 SP - 6566-6575 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-2942700403&partnerID=MN8TOARS ER - TY - CONF TI - Direct numerical simulation of disperse multiphase high-speed flows AU - Nourgaliev, R.R. AU - Dinh, T.N. AU - Theofanous, T.G. AU - Koning, J.M. AU - Greenman, R.M. AU - Nakafuji, G.T. C2 - 2004/// C3 - AIAA Paper DA - 2004/// SP - 10365-10375 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-2942741149&partnerID=MN8TOARS ER - TY - CONF TI - Characterization and predictability of transient heat transfer in an unstably stratified fluid layer during power startup AU - Dinh, T.N. AU - Tu, J.P. AU - Yang, Y.Z. AU - Nourgaliev, R.R. AU - Theofanous, T.G. AB - We study transient heat transfer in unstably stratified fluid layers of importance to thermal management of power equipment. A novel experimental approach was developed and used to obtain thermal images of a heater surface during a power startup and convection pattern formation. We use a high-resolution infrared camera to characterize thermal responses of a vapor- deposited nano-film heater. The experiments were analyzed with a computational fluid dynamics code, using different numerical schemes and grid refinements. It was found that the three- dimensional model based on solving Navier-Stokes and energy equation is generally capable of capturing thermal and flow behavior, including pattern formation in unstably stratified fluid layers. It was also found that presence of non-uniformities of boundary condition may explain the early onset of instabilities observed in experiments as compared to predictions by the direct numerical simulation. Implications of the findings for thermal management are discussed. C2 - 2004/// C3 - 37th AIAA Thermophysics Conference DA - 2004/// DO - 10.2514/6.2004-2733 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85088757090&partnerID=MN8TOARS ER - TY - CONF TI - Burnout in high heat flux boiling: The hydrodynaraic and physico-chemical factors AU - Dinh, T.N. AU - Tu, J.P. AU - Theofanous, T.G. C2 - 2004/// C3 - AIAA Paper DA - 2004/// SP - 1865-1872 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-2942709672&partnerID=MN8TOARS ER - TY - CONF TI - An experimental study of droplet breakup in supersonic flow: The effect of long-range interactions AU - Li, G.J. AU - Dinh, T.N. AU - Theofanous, T.G. C2 - 2004/// C3 - AIAA Paper DA - 2004/// SP - 12063-12073 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-2942741075&partnerID=MN8TOARS ER - TY - JOUR TI - Creating a baseline radiological standard for the waste isolation pilot plant underground AU - Chiou, Hung-Cheng AU - Hayes, Robert T2 - Isotopes in Environmental and Health Studies AB - 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. DA - 2004/9// PY - 2004/9// DO - 10.1080/10256010410001678053 VL - 40 IS - 3 SP - 213-220 J2 - Isotopes in Environmental and Health Studies LA - en OP - SN - 1025-6016 1477-2639 UR - http://dx.doi.org/10.1080/10256010410001678053 DB - Crossref KW - background radiation KW - radiation protection KW - radiological standard KW - salt mine KW - transuranic waste KW - waste disposal ER - TY - JOUR TI - CURVE FITTING AIR SAMPLE FILTER DECAY CURVES TO ESTIMATE TRANSURANIC CONTENT AU - Hayes, Robert B. AU - Chiou, Hung Cheng T2 - Health Physics AB - 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. DA - 2004/1// PY - 2004/1// DO - 10.1097/00004032-200401000-00010 VL - 86 IS - 1 SP - 80-91 KW - air sampling KW - monitoring KW - air KW - computer calculations KW - ventilation ER - TY - JOUR TI - A NEW TECHNIQUE FOR PRELIMINARY ESTIMATES OF TRU ACTIVITY ON AIR SAMPLE FILTERS AND RADIOLOGICAL SMEARS AU - Hayes, Robert T2 - Health Physics AB - 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. DA - 2004/// PY - 2004/// DO - 10.1097/00004032-200410000-00011 VL - 87 IS - 4 SP - 429-436 KW - air sampling KW - spectrometry KW - alpha KW - naturally occurring radionuclides KW - waste management ER - TY - JOUR TI - The Monte Carlo approach MCPUT for correcting pile-up distorted pulse-height spectra AU - Guo, WJ AU - Lee, SH AU - Gardner, RP T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT AB - Pulse pile-up distortion is a common problem for radiation spectroscopy measurements involving high counting rates. The Monte Carlo pile-up to true approach (MCPUT) is proposed and benchmarked in this article for correcting pile-up distorted pulse-height spectra to true spectra. In previous work, a Monte Carlo approach was used for predicting the pile-up distorted pulse-height spectra for high counting-rate measurements (“the forward calculation”). The present work improves the previous simulation by employing a better ADC dead-time model. Based on this improved “forward calculation”, the MCPUT approach introduces an iterative procedure for correcting pile-up distortions. Experiments with an Fe-55 source and a Si(Li) detector are used for benchmarking purposes. The MCPUT corrected spectrum for the high counting-rate measurement shows excellent agreement with the measured true spectrum at low counting rate with reduced chi-square as the quantitative measure. The approach is also efficient, as accurate calculations are possible in a few minutes. DA - 2004/10/1/ PY - 2004/10/1/ DO - 10.1016/j.nima.2004.05.089 VL - 531 IS - 3 SP - 520-529 SN - 1872-9576 KW - Monte Carlo KW - MCPUT KW - pulse pile up KW - spectroscopy ER - TY - JOUR TI - Surface modification of organic polymer films treated in atmospheric plasmas AU - Hwang, YJ AU - Matthews, S AU - McCord, M AU - Bourham, M T2 - JOURNAL OF THE ELECTROCHEMICAL SOCIETY AB - The effect of plasma treatment on surface characteristics of polyethylene terephthalate films was investigated using helium and oxygenated-helium atmospheric plasmas. Sample exposure to plasma was conducted in a closed ventilation test cell inside the main plasma chamber with variable exposure times. The percent weigh loss of the samples showed an initial increase followed by decrease with extended exposure time, indicating a combined mechanism of etching and redeposition. The wettability as measured by the contact angle showed a sharp initial increase followed by a steady-state trend with increased exposure time, suggesting a change in surface functionality. Atomic force microscopy analysis revealed increase in surface roughness, as well as evidence of redeposition of etched volatiles. Functionality changes were measured using X-ray photoelectron spectroscopy and these changes were correlated to the new plasma-induced properties. © 2004 The Electrochemical Society. All rights reserved. DA - 2004/// PY - 2004/// DO - 10.1149/1.1756891 VL - 151 IS - 7 SP - C495-C501 SN - 1945-7111 ER - TY - JOUR TI - Using the Monte Carlo - Library Least-Squares (MCLLS) approach for the in vivo XRF measurement of lead in bone AU - Guo, WJ AU - Gardner, RP AU - Todd, AC T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT AB - The Monte Carlo – Library Least-Squares (MCLLS) method has been developed by the Center for Engineering Applications of Radioisotopes for various XRF applications of multi-elemental composition analysis and implemented with the CEARXRF code. In the present work, it is successfully applied to the in vivo XRF measurement of lead in bone and benchmarked by the measurement of a plaster of Paris phantom of known lead concentration. It is implicitly assumed that if the approach works for this sample that closely approximates the real problem of interest, it will also work for the real in vivo case when the proper description of the real case is used. Traditional techniques for XRF analysis are reviewed briefly and the full advantages of the MCLLS method are discussed. Simulation results are presented that are in good agreement with experimental results. The applicability of the MCLLS method to the lead in bone measurement is supported by the good fitting results obtained with simulated Monte Carlo elemental library spectra and close agreement between simulated and experimental spectra from a calcium-rich matrix-based calibration standard in a test geometrical configuration. DA - 2004/1/11/ PY - 2004/1/11/ DO - 10.1016/j.nima.2003.09.030 VL - 516 IS - 2-3 SP - 586-593 SN - 0168-9002 KW - in vivo lead in bone measurement KW - XRF KW - least-squares fitting KW - MCLLS KW - CEARXRF ER - TY - JOUR TI - Ultratough nanocrystalline copper with a narrow grain size distribution AU - Youssef, KM AU - Scattergood, RO AU - Murty, KL AU - Koch, CC T2 - APPLIED PHYSICS LETTERS AB - We report a unique way of using mechanical milling/in situ consolidation at both liquid-nitrogen and room temperature to produce artifact-free nanocrystalline Cu(23nm) with a narrow grain size distribution. This nanocrystalline Cu exhibits an extraordinarily high yield strength (770MPa), as predicted from a Hall–Petch extrapolation, along with good ductility (comparable with ∼30% uniform tensile elongation). Possible factors leading to this excellent optimization of strength and ductility are discussed. DA - 2004/8/9/ PY - 2004/8/9/ DO - 10.1063/1.1779342 VL - 85 IS - 6 SP - 929-931 SN - 1077-3118 ER - TY - JOUR TI - Plasma characteristics in pulsed direct current reactive magnetron sputtering of aluminum nitride thin films AU - Lee, Jung W. AU - Cuomo, Jerome J. AU - Bourham, Mohamed A. T2 - Journal of Vacuum Science & Technology A AB - Plasma diagnostics is important to identify plasma parameters and generate reproducible plasma in magnetron sputtering. Langmuir probes have been used to measure local plasma parameters such as electron temperature (Te), charge densities (ne and ni), and plasma potential (Vp). Pulsed direct current (dc) power in the midfrequency range (50–250 kHz) has been used in growing insulating films without charging accumulations at target. Recent investigations showed increased energetic particle bombardment of the substrate in pulsed power. In this work, aluminum nitride thin films were fabricated by pulsed dc power sputter deposition. The argon and nitrogen plasma was characterized by Langmuir probe measurement. The electron temperature in argon and nitrogen plasma was observed to increased from 3.06 to 5.32 eV when the pulsed dc frequency increased from 75 to 250 kHz. The ion density and energy flux were found to increase with frequency. This is believed to be from the stochastic heating generated by the fast oscillation in the target voltage wave form. The measured plasma characteristics were correlated with the crystal orientation of AlN thin films. The crystal structure of AlN thin films changed to (002) preferred orientations as the ion and energy flux increased. DA - 2004/3// PY - 2004/3// DO - 10.1116/1.1641049 VL - 22 IS - 2 SP - 260–263 SN - 1520-8559 ER - TY - JOUR TI - Investigation into etching mechanism of polyethylene terephthalate (PET) films treated in helium and oxygenated-helium atmospheric plasmas AU - Matthews, , SR AU - Hwang, YJ AU - McCord, MG AU - Bourham, MA T2 - JOURNAL OF APPLIED POLYMER SCIENCE AB - Abstract This research makes an investigation into the etching mechanism of atmospheric plasma conditions on the surface of polyethylene terephthalate (PET) films. Two types of untreated PET films (S/200 and S/500) were exposed to plasma for 0 to 5.0 min in 30‐s increments. The first set of each film type was treated in helium plasma, while the second was treated in oxygenated‐helium plasma. Differential Scanning Calorimetry (DSC) was used to characterize pre‐ and post‐exposure films. Weight changes and the degree of solubility were also determined. Based on peak area results, the percent crystallinity of PET S/200 increased by an average of 4.57% (helium treated) and 13.56% (oxygenated‐helium treated), while the S/500 showed only a small increase. There was no significant change in the melting or crystallization temperatures of either film type, indicating a decrease in amorphous content versus an increase in crystalline material. Weight loss analysis supports this theory. Solubility testing revealed a continual decrease in swelling as exposure time was increased. A model was developed to predict the change in the degree of solubility for polyphase surfaces considering the etching rate per phase. The model was applied to PET with good correlation between the model and experimental data. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2383–2389, 2004 DA - 2004/12/15/ PY - 2004/12/15/ DO - 10.1002/app.21162 VL - 94 IS - 6 SP - 2383-2389 SN - 1097-4628 KW - films KW - surfaces KW - modifications KW - modeling KW - plasma ER - TY - JOUR TI - Super-nodal methods for space-time kinetics AU - Mertyurek, U AU - Turinsky, PJ T2 - NUCLEAR SCIENCE AND ENGINEERING AB - A Super-Nodal method is developed to improve computational efficiency of core simulations for three-dimensional (3-D) core neutronics models. Computational performance of the neutronics model is increased by reducing the number of spatial nodes used in the core modeling. The Super-Nodal method reduces the errors associated with the use of coarse nodes in the analyses by providing a new set of cross sections and discontinuity factors for the new nodalization. These so-called homogenization parameters are obtained by employing a consistent collapsing technique.During this research a new type of singularity, namely, “fundamental mode singularity,” is addressed in the analytical nodal method solution. The “coordinate shifting” approach is developed as a method to address this singularity. Also, the “buckling shifting” approach is developed as an alternative to address the “zero buckling singularity.” In the course of addressing the treatment of these singularities, an effort was made to provide better and more robust results from the Super-Nodal method by developing several new methods for determining the collapsed diffusion coefficient. A simple error analysis based on the relative residual in the 3-D few-group diffusion equation at the fine mesh level is also introduced in this work. DA - 2004/6// PY - 2004/6// DO - 10.13182/NSE04-A2422 VL - 147 IS - 2 SP - 93-126 SN - 1943-748X ER - TY - JOUR TI - Two-dimensional diagonal summing of coincidence spectra for bulk PGNAA applications AU - Metwally, WA AU - Gardner, RP AU - Mayo, CW T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT AB - Abstract In the past 10 years, new electronic devices have been developed that allow fast coincidence measurements to be performed that are capable of simultaneously recording the individual spectra as well as the coincidence spectra of multiple detectors. Utilizing these devices with computer software allows multiparameter data acquisition which adds much more flexibility in data analysis. One of the capabilities that is enabled is that of obtaining two-dimensional spectra. In this work, the use of this equipment and the two-dimensional spectra obtained with it are used to allow two-dimensional diagonal summing. The main advantages of this approach are improved peak resolution and very low background (Compton continuum). Possible uses of the two-dimensional diagonal summing are identifying coincidence schemes, performing elemental analysis, and identifying trace elements in bulk samples. The spectra obtained are very promising for these applications. DA - 2004/6/11/ PY - 2004/6/11/ DO - 10.1016/j.nima.2004.02.012 VL - 525 IS - 3 SP - 511-517 SN - 1872-9576 KW - two-dimensional diagonal summing KW - gamma-gamma coincidence KW - PGNAA ER - TY - JOUR TI - The analog linear interpolation approach for Monte Carlo simulation of PGNAA: The CEARPGA code AU - Zhang, WC AU - Gardner, RP T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS AB - The analog linear interpolation approach (ALI) has been developed and implemented to eliminate the big weight problem in the Monte Carlo simulation code CEARPGA. The CEARPGA code was previously developed to generate elemental library spectra for using the Monte Carlo – library least-squares (MCLLS) approach in prompt gamma-ray neutron activation analysis (PGNAA). In addition, some other improvements to this code have been introduced, including (1) adopting the latest photon cross-section data, (2) using an improved detector response function, (3) adding the neutron activation backgrounds, (4) generating the individual natural background libraries, (5) adding the tracking of annihilation photons from pair production interactions outside of the detector and (6) adopting a general geometry package. The simulated result from the new CEARPGA code is compared with those calculated from the previous CEARPGA code and the MCNP code and experimental data. The new CEARPGA code is found to give the best result. DA - 2004/1// PY - 2004/1// DO - 10.1016/S0168-583X(03)01544-1 VL - 213 SP - 116-123 SN - 0168-583X KW - Monte Carlo simulation KW - PGNAA KW - neutron activation analysis KW - sample analysis KW - library least-squares KW - Monte Carlo code ER - TY - JOUR TI - Preliminary studies on K and L coincidence spectroscopy for optimizing the in vivo XRF measurement of lead in bone AU - Guo, WJ AU - Gardner, RP AU - Metwally, WA T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS AB - Previous studies treated the optimal combined K and L XRF system which consists of a Cd-109 point source, a low energy Ge detector (LEGe) and a Si(Li) detector. The Monte-Carlo library least-squares (MCLLS) approach and differential operator approach were treated separately. In this work, an approach for combining the MCLLS approach with the differential operator approach (MCDOLLS) is presented and an optimal configuration for coincidence spectroscopy of K and L X-rays is proposed based on preliminary experimental data. DA - 2004/1// PY - 2004/1// DO - 10.1016/S0168-583X(03)01674-4 VL - 213 SP - 574-578 SN - 0168-583X KW - XRF KW - K and L X-ray coincidence KW - in vivo lead in bone measurement KW - MCLLS KW - differential operator ER - TY - JOUR TI - Optimization of the steady neutron source technique for absorption cross section measurement by using an Sb-124-Be neutron source AU - Sun, J AU - Gardner, RP T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS AB - An improved experimental approach has been developed to determine thermal neutron absorption cross sections. It uses an 124Sb–Be neutron source which has an average neutron energy of only about 12 keV. It can be moderated in either a water tank or a paraffin filled box and can be used for aqueous or powder samples. This new design is first optimized by MCNP simulation and then benchmarked and calibrated with experiments to verify the simulations and realize the predicted improved measurement sensitivity and reproducibility. The 124Sb–Be source device is from 1.35 to 1.71 times more sensitive than the previous method based on the use of a 252Cf source. DA - 2004/1// PY - 2004/1// DO - 10.1016/S0168-583X(03)01527-1 VL - 213 SP - 22-28 SN - 0168-583X KW - absorption cross section KW - steady neutron source KW - sensitivity KW - MCNP ER - TY - JOUR TI - Elemental PGNAA analysis using gamma-gamma coincidence counting with the library least-squares approach AU - Metwally, WA AU - Gardner, RP AU - Mayo, CW T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS AB - Abstract An accurate method for determining elemental analysis using gamma–gamma coincidence counting is presented. To demonstrate the feasibility of this method for PGNAA, a system of three radioisotopes (Na-24, Co-60 and Cs-134) that emit coincident gamma rays was used. Two HPGe detectors were connected to a system that allowed both singles and coincidences to be collected simultaneously. A known mixture of the three radioisotopes was used and data was deliberately collected at relatively high counting rates to determine the effect of pulse pile-up distortion. The results obtained, with the library least-squares analysis, of both the normal and coincidence counting are presented and compared to the known amounts. The coincidence results are shown to give much better accuracy. It appears that in addition to the expected advantage of reduced background, the coincidence approach is considerably more resistant to pulse pile-up distortion. DA - 2004/1// PY - 2004/1// DO - 10.1016/S0168-583X(03)01660-4 VL - 213 SP - 394-399 SN - 1872-9584 KW - PGNAA KW - gamma-gamma coincidence ER - TY - JOUR TI - A semi-empirical model for a Sr-90 beta-particle transmission thickness gauge for aluminum alloys AU - Gardner, RP AU - Metwally, WA AU - Shehata, A T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS AB - A semi-empirical model is derived and tested for a 90Sr beta-particle transmission thickness gauge for aluminum alloys. Monte Carlo simulation is also used to verify the forward scatter part of the model. The model accurately accounts for thickness as well as forward scatter, gamma-ray background, and the measurement interference of sample density and composition. The model parameters are obtained and the model is benchmarked with industrial experimental data from a 90Sr(90Y) gauge. DA - 2004/1// PY - 2004/1// DO - 10.1016/S0168-583X(03)01582-9 VL - 213 SP - 357-363 SN - 0168-583X ER - TY - JOUR TI - A Monte Carlo simulation approach for generating NaI detector response functions (DRFs) that accounts for non-linearity and variable flat continua AU - Gardner, RP AU - Sood, A T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS AB - A new approach to generating detector response functions (DRFs) for NaI detectors is developed and demonstrated. It consists of using Monte Carlo simulation with a specific purpose code (named g03) that utilizes relatively rigorous gamma-ray transport with very simple electron transport. The approach accounts for two phenomena that have not been previously treated in this way: NaI non-linearity and the variable flat continua part of the DRF. The first is accounted for by utilizing the known non-linear relationship between NaI scintillation efficiency and deposited electron energy within the Monte Carlo code. The second is accounted for by using a semi-empirical relationship between electron range and incident gamma-ray energy within the Monte Carlo code. The resulting DRFs for 3″ × 3″ and 6″ × 6″ NaI detectors are benchmarked with the extensive existing data of Heath [AEC Research and Development Report, Physics, TID-4500] for the 3″ × 3″ detectors and with new data for the 6″ × 6″ detectors. Results indicate that the approach is accurate and the use of this approach should increase the accuracy of prompt gamma-ray neutron activation analysis significantly. DA - 2004/1// PY - 2004/1// DO - 10.1016/S0168-583X(03)01539-8 VL - 213 SP - 87-99 SN - 0168-583X KW - detector response function KW - Monte Carlo simulation KW - NaI non-linearity KW - flat continua KW - Prompt gamma-ray neutron activation analysis ER - TY - JOUR TI - Plasma and antimicrobial treatment of nonwoven fabrics for surgical gowns AU - Virk, RK AU - Ramaswamy, GN AU - Bourham, M AU - Bures, BL T2 - TEXTILE RESEARCH JOURNAL AB - Plasma treatments are gaining popularity in the textile industry due to their numerous advantages over conventional wet processing techniques. In this study, the nonwoven fabric Sontara®, commonly used for surgical gowns, is treated with antimicrobial finishes and a plasma containing fluorocarbon gas. Treated samples are evaluated for changes in physical and functional characteristics. The plasma treatment does not alter the weight, thickness, stiffness, air permeability, and breaking strength and elongation. Plasma-treated and water-repellent Sontara samples show higher blood and water resistance compared to other treatments. Plasma-treated samples also show a zone of inhibition for Staphylococcus aureus, thus providing a barrier against microbes. There is no zone of inhibition for the water repellent Sontara, untreated, and wet control samples. This implies that the nonwoven fabric treated with plasma can provide a better barrier against microbes than commonly available surgical gown fabric with a fluorocarbon finish. DA - 2004/12// PY - 2004/12// DO - 10.1177/004051750407401208 VL - 74 IS - 12 SP - 1073-1079 SN - 1746-7748 ER - TY - JOUR TI - Stabilization of prompt gamma-ray neutron activation analysis (PGNAA) spectra from NaI detectors AU - Metwally, WA AU - Gardner, RP T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT AB - Abstract NaI detectors are still used frequently in industrial Prompt Gamma-Ray Neutron Activation Analysis applications such as in bulk material analysis. They have the advantages of being efficient for high-energy gamma rays, being relatively rugged, and being able to be used without cooling. When using NaI detectors, and consequently photomultiplier tubes, the quality of the data can drastically deteriorate through gain and zero shifts that result in spectral smearing due to temperature and/or counting rate changes. A new offline approach is presented to stabilize the NaI spectral drift. The approach is not sensitive to the cause of the drift and takes into account the NaI and ADC non-linearities. Peak resolution is improved substantially when this approach is used in the presence of spectral drift. DA - 2004/6/11/ PY - 2004/6/11/ DO - 10.1016/j.nima.2004.02.011 VL - 525 IS - 3 SP - 518-521 SN - 1872-9576 KW - spectral drift KW - spectrum stabilization KW - temperature and counting rate drifts KW - NaI non-linearity ER - TY - JOUR TI - Nondestructive monitoring of structural materials using automated ball indentation (ABI) technique AU - Murty, KL AU - Mathew, MD T2 - NUCLEAR ENGINEERING AND DESIGN AB - Materials used for high temperature components in nuclear power generation, aerospace, chemical and process plants undergo changes in their microstructure during operation in service leading to degradation in their mechanical properties. Monitoring the progressive changes in the mechanical properties is very important from the point of view of ensuring the structural integrity of the components and also for possible extension of their useful service life. Nondestructive methods for directly evaluating the mechanical properties are required for the success of any materials aging and life management program. In this paper, we describe an innovative automated technique based on ball indentation that can be used for laboratory and field applications in order to measure the mechanical and fracture properties of materials. Typical results from laboratory studies on engineering materials are also presented. DA - 2004/3// PY - 2004/3// DO - 10.1016/j.nucengdes.2003.06.006 VL - 228 IS - 1-3 SP - 81-96 SN - 1872-759X ER - TY - JOUR TI - Electrical characterization of B-10 doped diamond irradiated with low thermal neutron fluence AU - Reed, ML AU - Reed, MJ AU - Jagannadham, K AU - Verghese, K AU - Bedair, SM AU - El-Masry, N AU - Butler, JE T2 - JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A AB - A sample of B10 isotope doped diamond was neutron irradiated to a thermal fluence of 1.3×1019 neutron cm−2. The diamond sample was cooled continuously during irradiation in a nuclear reactor. Li7 is formed by nuclear transmutation reaction from B10. Characterization for electrical conductance in the temperature range of 160 K&lt;T&lt;600 K was performed on an unirradiated B10 doped sample and the B10 doped and irradiated sample. The unirradiated diamond sample showed p-type conductance at higher temperature (T&gt;200 K) and p-type surface conductance at lower temperature (T&lt;200 K). The irradiated sample showed decreasing conductance below 230 K and increasing conductance above 230 K with increasing temperature. Furthermore, the conductance showed a decrease above 400 K followed by an increase above 500 K. The observed behavior below 400 K with increase in temperature is interpreted in terms of compensation of surface p-type carriers by n-type bulk carriers generated from Li7 that is formed by nuclear transmutation reaction from B10 atoms. Also, compensation of n-type carriers from Li7 by p-type carriers from B10 is used to interpret the conductance above 400 K. A low concentration of radiation induced defects, absence of defect complexes, and the low activation energy of n-type Li7 are thought responsible for the observed variation of conductance in the irradiated diamond. The present results illustrate that neutron transmutation from B10 doped diamond is a useful method to achieve n-type conductivity in diamond. DA - 2004/// PY - 2004/// DO - 10.1116/1.1763910 VL - 22 IS - 4 SP - 1191-1194 SN - 1520-8559 ER - TY - JOUR TI - A new Monte Carlo assisted approach to detector response functions AU - Sood, A AU - Gardner, RP T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS AB - The physical mechanisms that describe the components of NaI, Ge and Si(Li) detector responses have been investigated using Monte Carlo simulation. The mechanisms described focus on the shape of the Compton edge, the magnitude of the flat continuum, and the shape of the exponential tails features. These features are not accurately predicted by previous Monte Carlo simulations. Probable interaction mechanisms for each detector response component are given based on this Monte Carlo simulation. DA - 2004/1// PY - 2004/1// DO - 10.1016/S0168-583X(03)01540-4 VL - 213 SP - 100-104 SN - 0168-583X KW - detector response KW - Monte Carlo KW - spectrometry ER -