@book{longland_2024, title={Measurements at the Facility for Experiments of Nuclear Reactions in Stars (FENRIS) (Final Technical Report)}, url={https://doi.org/10.2172/2322513}, DOI={10.2172/2322513}, author={Longland, Richard}, year={2024}, month={Mar} }
 @article{fox_longland_marshall_chaves_2024, title={Resolution of 40Ca to Constrain Potassium in NGC 2419}, volume={132}, ISSN={["1079-7114"]}, url={https://doi.org/10.1103/PhysRevLett.132.062701}, DOI={10.1103/PhysRevLett.132.062701}, abstractNote={The globular cluster NGC 2419 was the first to exhibit a Mg-K anticorrelation, linked to hydrogen burning at temperatures between 80-260 MK. However, the key K-destroying reaction, ^{39}K(p,γ)^{40}Ca, has a large rate uncertainty in this range. We significantly constrain this rate with a high resolution ^{39}K(^{3}He,d)^{40}Ca study. We resolve the E_{r}^{c.m.}=154  keV resonance in ^{39}K+p for the first time, increasing the previous rate by up to a factor 13 and reducing its 1σ width by up to a factor of 42. Reaction network calculations for NGC 2419 suggest that this could lower temperatures needed to reproduce the Mg-K anticorrelation.}, number={6}, journal={PHYSICAL REVIEW LETTERS}, author={Fox, W. and Longland, R. and Marshall, C. and Chaves, F. Portillo}, year={2024}, month={Feb} }
 @article{cooper_hunt_downen_setoodehnia_portillo_marshall_clegg_champagne_longland_2023, title={Correlated characterization of 20Ne-implanted targets using nuclear reaction analysis, Rutherford backscattering spectrometry, and ion transport modeling}, volume={1056}, ISSN={["1872-9576"]}, DOI={10.1016/j.nima.2023.168654}, abstractNote={We present the preparation and characterization of a large sample of implanted noble gas targets for use in precision nuclear astrophysics measurements with intense proton beams. Tantalum and titanium backings were prepared using wet-acid etching, outgassed via resistive heating, and implanted with 20Ne+ beams from differing ion sources. These experimental targets were investigated using both nuclear reaction analysis techniques on the 1169-keV resonance in 20Ne(p, γ)21Na and Rutherford backscattering spectrometry analysis with 2-MeV α-particle beams. Results from these analyses reveal small target-to-target variations in stoichiometry, while exhibiting excellent agreement independent of ion-beam analysis method. We also present a self-consistent validation of the nuclear reaction analysis results using ion transport simulations in TRIM-2013 that rely on input parameters from SIMNRA scattering-yield fits to Rutherford backscattering spectra. In addition to a complete description of the implantation profile, this analysis method provides an alternate solution for characterizing a large sample of implanted targets when no suitable resonances are available for nuclear reaction analysis.}, journal={NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT}, author={Cooper, A. L. and Hunt, S. and Downen, L. and Setoodehnia, K. and Portillo, F. and Marshall, C. and Clegg, T. B. and Champagne, A. E. and Longland, R.}, year={2023}, month={Nov} }
 @article{marshall_setoodehnia_cinquegrana_kellly_chaves_karakas_longland_2023, title={New constraints on sodium production in globular clusters from the 23Na(3He, d) 24Mg reaction}, volume={107}, ISSN={["2469-9993"]}, DOI={10.1103/PhysRevC.107.035806}, abstractNote={The star-to-star anticorrelation of sodium and oxygen is a defining feature of globular clusters, but, to date, the astrophysical site responsible for this unique chemical signature remains unknown. Sodium enrichment within these clusters depends sensitively on reaction rate of the sodium destroying reactions $^{23}\mathrm{Na}(p,\ensuremath{\gamma})$ and $^{23}\mathrm{Na}(p,\ensuremath{\alpha})$. In this paper, we report the results of a $^{23}\mathrm{Na}{(^{3}\mathrm{He},d)}^{24}\mathrm{Mg}$ transfer reaction carried out at Triangle Universities Nuclear Laboratory using a $21\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}\phantom{\rule{0.16em}{0ex}}^{3}\mathrm{He}$ beam. Astrophysically relevant states in $^{24}\mathrm{Mg}$ between $11<{E}_{x}<12\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}$ were studied using high-resolution magnetic spectroscopy, thereby allowing the extraction of excitation energies and spectroscopic factors. Bayesian methods are combined with the distorted wave Born approximation to assign statistically meaningful uncertainties to the extracted spectroscopic factors. For the first time, these uncertainties are propagated through to the estimation of proton partial widths. Our experimental data are used to calculate the reaction rate. The impact of the new rates are investigated using asymptotic giant branch star models. It is found that while the astrophysical conditions still dominate the total uncertainty, intramodel variations on sodium production from the $^{23}\mathrm{Na}(p,\ensuremath{\gamma})$ and $^{23}\mathrm{Na}(p,\ensuremath{\alpha})$ reaction channels are a lingering source of uncertainty.}, number={3}, journal={PHYSICAL REVIEW C}, author={Marshall, C. and Setoodehnia, K. and Cinquegrana, G. C. and Kellly, J. H. and Chaves, F. Portillo and Karakas, A. and Longland, R.}, year={2023}, month={Mar} }
 @article{portillo_longland_cooper_hunt_laird_marshall_setoodehnia_2023, title={Spin-parities of subthreshold resonances in the 18F(p, ?)15O reaction}, volume={107}, ISSN={["2469-9993"]}, url={https://doi.org/10.1103/PhysRevC.107.035809}, DOI={10.1103/PhysRevC.107.035809}, abstractNote={The $^{18}$F(p, $\alpha$)$^{15}$O reaction is key to determining the $^{18}$F abundance in classical novae. However, the cross section for this reaction has large uncertainties at low energies largely caused by interference effects. Here, we resolve a longstanding issue with unknown spin-parities of sub-threshold states in $^{19}$Ne that reduces these uncertainties. The $^{20}$Ne($^3$He, $^4$He)$^{19}$Ne neutron pick-up reaction was used to populate $^{19}$Ne excited states, focusing on the energy region of astrophysical interest ($\approx$ 6 - 7 MeV). The experiment was performed at the Triangle Universities Nuclear Laboratory using the high resolution Enge split-pole magnetic spectrograph. Spins and parities were found for states in the astrophysical energy range. In particular, the state at 6.133 MeV (E$_{r}^{\text{c.m.}} = -278$ keV) was found to have spin and parity of $3/2^+$ and we confirm the existence of an unresolved doublet close to 6.288 MeV (E$_{r}^{\text{c.m.}} = -120$ keV) with J$^{\pi}$ = $1/2^+$ and a high-spin state. Using these results, we demonstrate a significant factor of two decrease in the reaction rate uncertainties at nova temperatures.}, number={3}, journal={PHYSICAL REVIEW C}, author={Portillo, F. and Longland, R. and Cooper, A. L. and Hunt, S. and Laird, A. M. and Marshall, C. and Setoodehnia, K.}, year={2023}, month={Mar} }
 @article{adsley_williams_harrouz_carrasco-rojas_sereville_hammache_longland_bastin_davids_faestermann_et al._2023, title={Understanding globular cluster abundances through nuclear reactions}, volume={2586}, ISBN={["*****************"]}, ISSN={["1742-6596"]}, DOI={10.1088/1742-6596/2586/1/012100}, abstractNote={Abstract}, journal={28TH INTERNATIONAL NUCLEAR PHYSICS CONFERENCE, INPC 2022}, author={Adsley, P. and Williams, M. and Harrouz, D. S. and Carrasco-Rojas, D. P. and Sereville, N. and Hammache, F. and Longland, R. and Bastin, B. and Davids, B. and Faestermann, T. and et al.}, year={2023} }
 @article{psaltis_chen_longland_connolly_brune_davids_fallis_giri_greife_hutcheon_et al._2022, title={Direct Measurement of Resonances in 7Be(alpha,gamma )11C Relevant to vp-Process Nucleosynthesis}, volume={129}, ISSN={["1079-7114"]}, url={https://doi.org/10.1103/PhysRevLett.129.162701}, DOI={10.1103/PhysRevLett.129.162701}, abstractNote={We have performed the first direct measurement of two resonances of the ^{7}Be(α,γ)^{11}C reaction with unknown strengths using an intense radioactive ^{7}Be beam and the DRAGON recoil separator. We report on the first measurement of the 1155 and 1110 keV resonance strengths of 1.73±0.25(stat)±0.40(syst)  eV and 125_{-25}^{+27}(stat)±15(syst)  meV, respectively. The present results have reduced the uncertainty in the ^{7}Be(α,γ)^{11}C reaction rate to ∼9.4%-10.7% over T=1.5-3  GK, which is relevant for nucleosynthesis in the neutrino-driven outflows of core-collapse supernovae (νp process). We find no effect of the new, constrained reaction rate on νp-process nucleosynthesis.}, number={16}, journal={PHYSICAL REVIEW LETTERS}, author={Psaltis, A. and Chen, A. A. and Longland, R. and Connolly, D. S. and Brune, C. R. and Davids, B. and Fallis, J. and Giri, R. and Greife, U. and Hutcheon, D. A. and et al.}, year={2022}, month={Oct} }
 @article{harrouz_sereville_adsley_hammache_longland_bastin_faestermann_hertenberger_la cognata_lamia_et al._2022, title={Experimental study of the Si-30(He-3, d) P-31 reaction and thermonuclear reaction rate of Si-30(p, gamma)( 3)1P}, volume={105}, ISSN={["2469-9993"]}, url={https://doi.org/10.1103/PhysRevC.105.015805}, DOI={10.1103/PhysRevC.105.015805}, abstractNote={D. S. Harrouz, N. de Séréville, ∗ P. Adsley, 3, † F. Hammache, R. Longland, 5 B. Bastin, T. Faestermann, R. Hertenberger, M. La Cognata, L. Lamia, 10 A. Meyer, S. Palmerini, 12 R. G. Pizzone, S. Romano, 10, 13 A. Tumino, 14 and H.-F. Wirth Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France School of Physics, University of the Witwatersrand, Johannesburg 2050, South Africa iThemba Laboratory for Accelerator Based Sciences, Somerset West 7129, South Africa North Carolina State University, Raleigh, NC 27695 Triangle Universities Nuclear Laboratory, Durham, NC 27708 Grand Accélérateur National d’Ions Lourds (GANIL), CEA/DRF-CNRS/IN2P3, Bd. Henri Becquerel, 14076 Caen, France Physik Department E12, Technische Universität München, D-85748 Garching, Germany Fakultät für Physik, Ludwig-Maximilians-Universität München, D-85748 Garching, Germany Laboratori Nazionali del Sud Istituto Nazionale di Fisica Nucleare, Via Santa Sofia 62, 95123 Catania, Italy Dipartimento di Fisica e Astronomia E. Majorana, Univ. di Catania, Catania, Italy Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, Perugia, Italy Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, Perugia, Italy Centro Siciliano di Fisica Nucleare e Struttura della Materia-CSFNSM, Catania, Italy Facoltà di Ingegneria e Architettura, Università degli Studi di Enna, Italy (Dated: January 11, 2022)}, number={1}, journal={PHYSICAL REVIEW C}, author={Harrouz, D. S. and Sereville, N. and Adsley, P. and Hammache, F. and Longland, R. and Bastin, B. and Faestermann, T. and Hertenberger, R. and La Cognata, M. and Lamia, L. and et al.}, year={2022}, month={Jan} }
 @article{psaltis_chen_longland_connolly_brune_davids_fallis_giri_greife_hutcheon_et al._2022, title={First inverse kinematics measurement of resonances in 7Be(alpha, gamma)11C relevant to neutrino-driven wind nucleosynthesis using DRAGON}, volume={106}, ISSN={["2469-9993"]}, DOI={10.1103/PhysRevC.106.045805}, abstractNote={A possible mechanism to explain the origin of the light $p$ nuclei in the Galaxy is the nucleosynthesis in the proton-rich neutrino-driven wind ejecta of core-collapse supernovas via the $\ensuremath{\nu}p$ process. However, this production scenario is very sensitive to the underlying supernova dynamics and the nuclear physics input. As far as the nuclear uncertainties are concerned, the breakout from the $pp$ chains via the $^{7}\mathrm{Be}(\ensuremath{\alpha},\ensuremath{\gamma})^{11}\mathrm{C}$ reaction has been identified as an important link which can influence the nuclear flow and, therefore, the efficiency of the $\ensuremath{\nu}p$ process. However, its reaction rate is poorly known over the relevant temperature range, $T$ = 1.5--3 GK. We report on the first direct measurement of two resonances of the $^{7}\mathrm{Be}(\ensuremath{\alpha},\ensuremath{\gamma})^{11}\mathrm{C}$ reaction with previously unknown strengths using an intense radioactive $^{7}\mathrm{Be}$ beam from the Isotope Separator and Accelerator (ISAC-I) Center facility and the DRAGON recoil separator in inverse kinematics. We have decreased the $^{7}\mathrm{Be}(\ensuremath{\alpha},\ensuremath{\gamma})^{11}\mathrm{C}$ reaction rate uncertainty to $\ensuremath{\approx}9.4\text{--}10.7$% over the relevant temperature region.}, number={4}, journal={PHYSICAL REVIEW C}, author={Psaltis, A. and Chen, A. A. and Longland, R. and Connolly, D. S. and Brune, C. R. and Davids, B. and Fallis, J. and Giri, R. and Greife, U. and Hutcheon, D. A. and et al.}, year={2022}, month={Oct} }
 @article{frost-schenk_adsley_laird_longland_angus_barton_choplin_diget_hirschi_marshall_et al._2022, title={The impact of O-17 + alpha reaction rate uncertainties on the s-process in rotating massive stars}, volume={514}, ISSN={["1365-2966"]}, DOI={10.1093/mnras/stac1373}, abstractNote={ABSTRACT}, number={2}, journal={MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY}, author={Frost-Schenk, J. and Adsley, P. and Laird, A. M. and Longland, R. and Angus, C. and Barton, C. and Choplin, A. and Diget, C. Aa and Hirschi, R. and Marshall, C. and et al.}, year={2022}, month={Jun}, pages={2650–2657} }
 @article{marshall_setoodehnia_portillo_kelley_longland_2021, title={New energy for the 133-keV resonance in the Na-23(p, gamma) Mg-24 reaction and its impact on nucleosynthesis in globular clusters}, volume={104}, ISSN={["2469-9993"]}, url={https://doi.org/10.1103/PhysRevC.104.L032801}, DOI={10.1103/PhysRevC.104.L032801}, abstractNote={Globular cluster stars exhibit star-to-star anticorrelations between oxygen and sodium in their atmospheres. An improved description of the sodium-destroying $^{23}\mathrm{Na}+\mathrm{p}$ reaction rates is essential to understanding these observations. We present an energy analysis of $^{24}\mathrm{Mg}$ states based on a new measurement of the $^{23}\mathrm{Na}(^{3}\mathrm{He},\mathrm{d})^{24}\mathrm{Mg}$ reaction. A key resonance in $^{23}\mathrm{Na}(\mathrm{p},\ensuremath{\gamma})^{24}\mathrm{Mg}$ is found to be at ${E}_{r}^{\text{c.m.}}=133(3)$ keV, 5 keV lower than previously adopted. This finding has a dramatic effect on the $^{23}\mathrm{Na}(\mathrm{p},\ensuremath{\gamma})^{24}\mathrm{Mg}$ reaction rate, increasing it by a factor of 2 for the recommended rate. The nucleosynthesis impact of this change is investigated.}, number={3}, journal={PHYSICAL REVIEW C}, author={Marshall, C. and Setoodehnia, K. and Portillo, F. and Kelley, J. H. and Longland, R.}, year={2021}, month={Sep} }
 @article{marshall_morfouace_sereville_longland_2020, title={Bayesian analysis of the Zn-70(d, He-3) Cu-69 transfer reaction}, volume={102}, ISSN={["2469-9993"]}, DOI={10.1103/PhysRevC.102.024609}, abstractNote={Transfer reactions provide information about the single-particle nature of nuclear levels. In particular, the differential cross sections from these measurements are sensitive to the angular momentum of the transferred particle and the spectroscopic factor of the populated level. However, the process of extracting these properties is subject to uncertainties, both from experimental and theoretical sources. By integrating the distorted wave Born approximation into a Bayesian model, we propagate these uncertainties through to the spectroscopic factors and orbital angular momentum values. We use previously reported data of the proton pickup reaction $^{70}$Zn$(d, ^3\!\text{He}) ^{69}$Cu as an example. By accounting for uncertainties in the experimental data, optical model parameters, and reaction mechanism, we find that the extracted spectroscopic factors for low lying states of $^{69}$Cu are subject to large, asymmetric uncertainties ranging from $35 \%$ to $108 \%$. Additionally, Bayesian model comparison is employed to assign probabilities to each of the allowed angular momentum transfers. This method confirms the assignments for many states, but suggests that the data for a state lying at $3.70$ MeV is better characterized by an $\ell = 3$ transfer, rather than the previously reported $\ell = 2$.}, number={2}, journal={PHYSICAL REVIEW C}, author={Marshall, C. and Morfouace, P. and Sereville, N. and Longland, R.}, year={2020}, month={Aug} }
 @article{longland_sereville_2020, title={Correlated energy uncertainties in reaction rate calculations}, volume={642}, ISSN={["1432-0746"]}, url={https://doi.org/10.1051/0004-6361/202038151}, DOI={10.1051/0004-6361/202038151}, abstractNote={Context. Monte Carlo methods can be used to evaluate the uncertainty of a reaction rate that arises from many uncertain nuclear inputs. However, until now no attempt has been made to find the effect of correlated energy uncertainties in input resonance parameters.}, journal={ASTRONOMY & ASTROPHYSICS}, author={Longland, Richard and Sereville, Nicolas}, year={2020}, month={Oct} }
 @article{meyer_sereville_laird_hammache_longland_lawson_pignatari_audouin_beaumel_fortier_et al._2020, title={Evaluation of the N-13(alpha, p)O-16 thermonuclear reaction rate and its impact on the isotopic composition of supernova grains}, volume={102}, ISSN={["2469-9993"]}, url={https://doi.org/10.1103/PhysRevC.102.035803}, DOI={10.1103/PhysRevC.102.035803}, abstractNote={Background: It has been recently suggested that hydrogen ingestion into the helium shell of massive stars could lead to high $^{13}\mathrm{C}$ and $^{15}\mathrm{N}$ excesses when the shock of a core-collapse supernova passes through its helium shell. This prediction questions the origin of extremely high $^{13}\mathrm{C}$ and $^{15}\mathrm{N}$ abundances observed in rare presolar SiC grains which is usually attributed to classical novae. In this context the $^{13}\mathrm{N}(\ensuremath{\alpha},p)^{16}\mathrm{O}$ reaction plays an important role since it is in competition with $^{13}\mathrm{N}\phantom{\rule{4pt}{0ex}}{\ensuremath{\beta}}^{+}$ decay to $^{13}\mathrm{C}$.Purpose: The $^{13}\mathrm{N}(\ensuremath{\alpha},p)^{16}\mathrm{O}$ reaction rate used in stellar evolution calculations comes from the Caughlan and Fowler compilation with very scarce information on the origin of this rate and with no associated uncertainty. The goal of this work is to provide a recommended $^{13}\mathrm{N}(\ensuremath{\alpha},p)^{16}\mathrm{O}$ reaction rate, based on available experimental data, with a meaningful statistical uncertainty.Method: Unbound nuclear states in the $^{17}\mathrm{F}$ compound nucleus were studied using the spectroscopic information of the analog states in $^{17}\mathrm{O}$ nucleus that were measured at the Tandem-Alto facility using the $^{13}\mathrm{C}(^{7}\mathrm{Li},t)^{17}\mathrm{O}$ $\ensuremath{\alpha}$-particle-transfer reaction. The $\ensuremath{\alpha}$-particle spectroscopic factors were derived using a finite-range distorted-wave Born approximation analysis. This spectroscopic information was used to calculate a recommended $^{13}\mathrm{N}(\ensuremath{\alpha},p)^{16}\mathrm{O}$ reaction rate with meaningful uncertainty using a Monte Carlo approach.Results: The $^{13}\mathrm{N}(\ensuremath{\alpha},p)^{16}\mathrm{O}$ reaction rate from the present work is found to be within a factor of two of the previous evaluation in the temperature range of interest, with a typical uncertainty of a factor $\ensuremath{\approx}2--3$. The source of this uncertainty has been identified to come from the three main contributing resonances at ${E}_{r}^{\mathrm{c}.\mathrm{m}.}=221$, 741, and 959 keV. This new error estimation translates to an overall uncertainty in the $^{13}\mathrm{C}$ production of a factor of 50 when using the lower and upper reaction rates in the conditions relevant for the $^{13}\mathrm{N}(\ensuremath{\alpha},p)^{16}\mathrm{O}$ activation.Conclusions: The main source of uncertainty on the re-evaluated $^{13}\mathrm{N}(\ensuremath{\alpha},p)^{16}\mathrm{O}$ reaction rate currently comes from the uncertain $\ensuremath{\alpha}$-particle width of relevant $^{17}\mathrm{F}$ states.}, number={3}, journal={PHYSICAL REVIEW C}, author={Meyer, A. and Sereville, N. de and Laird, A. M. and Hammache, F. and Longland, R. and Lawson, T. and Pignatari, M. and Audouin, L. and Beaumel, D. and Fortier, S. and et al.}, year={2020}, month={Sep} }
 @article{richter_brown_longland_wrede_denissenkov_fry_herwig_kurtulgil_pignatari_reifarth_2020, title={Shell-model studies of the astrophysical rp-process reactions S-34(p, gamma) Cl-35 and Cl-34g(,m)(p, gamma) Ar-35}, volume={102}, ISSN={["2469-9993"]}, url={https://doi.org/10.1103/PhysRevC.102.025801}, DOI={10.1103/PhysRevC.102.025801}, abstractNote={Background: Dust grains condensed in the outflows of presolar classical novae should have been present in the protosolar nebula. Candidates for such presolar nova grains have been found in primitive meteorites and can in principle be identified by their isotopic ratios, but the ratios predicted by state-of-the-art one-dimensional hydrodynamic models are uncertain due to nuclear-physics uncertainties.Purpose: To theoretically calculate the thermonuclear rates and uncertainties of the $^{34}\mathrm{S}(p,\ensuremath{\gamma})^{35}\mathrm{Cl}$ and $^{34g,m}\mathrm{Cl}(p,\ensuremath{\gamma})^{35}\mathrm{Ar}$ reactions and investigate their impacts on the predicted $^{34}\mathrm{S}/^{32}\mathrm{S}$ isotopic ratio for presolar nova grains.Method: A shell-model approach in a ($0+1$) $\ensuremath{\hbar}\ensuremath{\omega}$ model space was used to calculate the properties of resonances in the $^{34}\mathrm{S}(p,\ensuremath{\gamma})^{35}\mathrm{Cl}$ and $^{34g,m}\mathrm{Cl}(p,\ensuremath{\gamma})^{35}\mathrm{Ar}$ reactions and their thermonuclear rates. Uncertainties were estimated using a Monte Carlo method. The implications of these rates and their uncertainties on sulfur isotopic nova yields were investigated using a postprocessing nucleosynthesis code. The rates for transitions from the ground state of $^{34}\mathrm{Cl}$ as well as from the isomeric first excited state of $^{34}\mathrm{Cl}$ were explicitly calculated.Results: At energies in the resonance region near the proton-emission threshold, many negative-parity states appear. Energies, spectroscopic factors, and proton-decay widths are reported. The resulting thermonuclear rates are compared with previous determinations.Conclusions: The shell-model calculations alone are sufficient to constrain the variation of the $^{34}\mathrm{S}/^{32}\mathrm{S}$ ratios to within about 30%. Uncertainties associated with other reactions must also be considered, but in general we find that the $^{34}\mathrm{S}/^{32}\mathrm{S}$ ratios are not a robust diagnostic to clearly identify presolar grains made from nova ejecta.}, number={2}, journal={PHYSICAL REVIEW C}, author={Richter, W. A. and Brown, B. A. and Longland, R. and Wrede, C. and Denissenkov, P. and Fry, C. and Herwig, F. and Kurtulgil, D. and Pignatari, M. and Reifarth, R.}, year={2020}, month={Aug} }
 @article{richter_brown_longland_wrede_fry_denisenkov_herwig_kurtulgil_pignatari_reifarth_2020, title={Shell-model studies of the astrophysical rp-process reactions S-34(p,gamma)Cl-35 and Cl-34g,Cl-m(p,gamma)Ar-35}, volume={1643}, ISSN={["1742-6596"]}, DOI={10.1088/1742-6596/1643/1/012064}, abstractNote={Abstract}, journal={27TH INTERNATIONAL NUCLEAR PHYSICS CONFERENCE (INPC2019)}, author={Richter, W. A. and Brown, B. Alex and Longland, R. and Wrede, C. and Fry, C. and Denisenkov, P. and Herwig, F. and Kurtulgil, D. and Pignatari, M. and Reifarth, R.}, year={2020} }
 @article{hamill_woods_kahl_longland_greene_marshall_portillo_setoodehnia_2020, title={Study of the Mg-25(d,p)Mg-26 reaction to constrain the Al-25(p,gamma)Si-26 resonant reaction rates in nova burning conditions}, volume={56}, ISSN={["1434-601X"]}, DOI={10.1140/epja/s10050-020-00052-9}, abstractNote={Abstract}, number={2}, journal={EUROPEAN PHYSICAL JOURNAL A}, author={Hamill, C. B. and Woods, P. J. and Kahl, D. and Longland, R. and Greene, J. P. and Marshall, C. and Portillo, F. and Setoodehnia, K.}, year={2020}, month={Feb} }
 @article{dermigny_iliadis_champagne_longland_2020, title={Thermonuclear reaction rate of Si-30(p , gamma) P-31}, volume={102}, ISSN={["2469-9993"]}, DOI={10.1103/PhysRevC.102.014609}, abstractNote={Silicon synthesis in high-temperature hydrogen burning environments presents one possible avenue for the study of abundance anomalies in globular clusters. This was suggested in a previous study, which found that the large uncertainties associated with the $^{30}$Si(p,$\gamma$)$^{31}$P reaction rate preclude a firm understanding of the stellar conditions that give rise to the Mg-K anti-correlation observed in the globular cluster NGC 2419. In an effort to improve the reaction rate, we present new strength measurements of the $E_r^{lab} = 435$ keV and $E_r^{lab} = 501$ keV resonances in $^{30}$Si(p,$\gamma$)$^{31}$P. For the former, which was previously unobserved, we obtain a resonance strength of $\omega\gamma = (1.28 \pm 0.25$) $\times 10^{-4}$ eV. For the latter, we obtain a value of $\omega\gamma = (1.88 \pm 0.14)$ $\times 10^{-1}$ eV, which has a smaller uncertainty compared to previously measured strengths. Based on these results, the thermonuclear reaction rate has been re-evaluated. The impact of the new measurements is to lower the reaction rate by a factor of $\approx$10 at temperatures important to the study of NGC 2419. The rate uncertainty at these temperatures has also been reduced significantly.}, number={1}, journal={PHYSICAL REVIEW C}, author={Dermigny, John and Iliadis, Christian and Champagne, Art and Longland, Richard}, year={2020}, month={Jul} }
 @article{setoodehnia_kelley_marshall_chaves_longland_2019, title={Experimental study of Cl35 excited states via S32(α,p)}, volume={99}, DOI={10.1103/physrevc.99.055812}, abstractNote={Presolar grains originating in oxygen-neon novae may be identified by their sulfur isotopic ratios compared with theoretical estimates. These ratios depend on reliable $^{33}$S($p, \gamma$)$^{34}$Cl and $^{34}$S($p, \gamma$)$^{35}$Cl reaction rates. The latter rate has recently been computed based on experimental input, and many new excited states in $^{35}$Cl were discovered above the proton threshold. The experimental $^{34}$S($p, \gamma$)$^{35}$Cl rate was found to be 2 - 5 times smaller than the theoretical one, and the simulated $^{34}$S/$^{32}$S isotopic ratio for nova presolar grains was thus predicted to be smaller than that of type II supernova grains by up to a factor of 3.7. The present study was performed to confirm the existence of these new resonances, and to improve the remaining uncertainties in the $^{34}$S($p, \gamma$)$^{35}$Cl reaction rate. Energies and spin-parities of the $^{35}$Cl excited levels were investigated with an Enge split-pole spectrograph using the $^{32}$S($\alpha, p$)$^{35}$Cl reaction. Differential cross sections of the outgoing protons were measured at $E_{\alpha}$ = 21 MeV. The existence of the newly discovered states are largely confirmed, although a few states were not observed in this study. The spins and parities of several $^{35}$Cl states were assigned tentatively for the first time. The present $^{34}$S($p, \gamma$)$^{35}$Cl experimental thermonuclear reaction rate is consistent within 1$\sigma$ with the previous evaluation. However, our rate uncertainty is larger due to a more realistic treatment of the experimental uncertainties. The uncertainty in the present rate is up to a factor of 3.5 at nova temperatures. We recommend future work to focus on the unknown properties of four excited states of $^{35}$Cl at 6643 keV, 6761 keV, 6780 keV, and 6800 keV.}, number={5}, journal={Physical Review C}, publisher={American Physical Society (APS)}, author={Setoodehnia, K. and Kelley, J. H. and Marshall, C. and Chaves, F. Portillo and Longland, R.}, year={2019}, month={May} }
 @article{marshall_setoodehnia_kowal_portillo_champagne_hale_dummer_longland_2019, title={The Focal-Plane Detector Package on the TUNL Split-Pole Spectrograph}, volume={68}, ISSN={["1557-9662"]}, DOI={10.1109/TIM.2018.2847938}, abstractNote={A focal-plane detector for the Enge split-pole spectrograph at the Triangle Universities Nuclear Laboratory has been designed. The detector package consists of two position-sensitive gas avalanche counters: a gas proportionality energy loss section and a residual energy scintillator. This setup allows both particle identification and focal-plane reconstruction. In this paper, we will detail the construction of each section along with their accompanying electronics and data acquisition. Effects of energy loss throughout the detector, ray-tracing procedures, and resolution as a function of fill pressure and bias voltage are also investigated. A measurement of the 27Al $(d,p)$  reaction is used to demonstrate a detector performance and to illustrate a Bayesian method of energy calibration.}, number={2}, journal={IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Marshall, Caleb and Setoodehnia, Kiana and Kowal, Katie and Portillo, Federico and Champagne, Arthur E. and Hale, Stephen and Dummer, Andrew and Longland, Richard}, year={2019}, month={Feb}, pages={533–546} }
 @article{manwell_parikh_chen_séréville_adsley_irvine_hammache_stefan_longland_tomlinson_et al._2018, title={Effectiveness of using a magnetic spectrograph with the Trojan Horse method}, volume={940}, DOI={10.1088/1742-6596/940/1/012046}, abstractNote={The Trojan Horse method relies on performing reactions in a specific kinematic phase space that maximizes contributions of a quasi-free reaction mechanism. The hallmark of this method is that the incident particle can be accelerated to high enough energies to overcome the Coulomb barrier of the target, but once inside the target nucleus the relative motion of the clustered nuclei allows the reaction of interest to proceed at energies below this Coulomb Barrier. This method allows the experimentalist to probe reactions that have significance in astrophysics at low reaction energies that would otherwise be impossible due to the vanishing cross section. Traditionally the Trojan Horse method has been applied with the use of silicon detectors to observe the reaction products. In this study we apply the Trojan Horse method to a well studied reaction to examine the potential benefits of using a splitpole magnetic spectrograph to detect one of the reaction products. We have measure the three body 7Li(d,αn)α reaction to constrain the energy 7Li(d,α)α cross section. Measurements were first made using two silicon detectors, and then by replacing one detector with the magnetic spectrograph. The experimental design, limitations, and early results are discussed.}, journal={Journal of Physics: Conference Series}, publisher={IOP Publishing}, author={Manwell, S. and Parikh, A. and Chen, A. A. and Séréville, N. and Adsley, P. and Irvine, D. and Hammache, F. and Stefan, I. and Longland, R. F. and Tomlinson, J. and et al.}, year={2018}, month={Jan}, pages={012046} }
 @article{setoodehnia_marshall_kelley_liang_chaves_longland_2018, title={Excited states of Ca-39 and their significance in nova nucleosynthesis}, volume={98}, ISSN={["2469-9993"]}, DOI={10.1103/PhysRevC.98.055804}, abstractNote={Background: Discrepancies exist between the observed abundances of argon and calcium in oxygen-neon nova ejecta and those predicted by nova models. An improved characterization of the $^{38}$K($p, \gamma$)$^{39}$Ca reaction rate over the nova temperature regime ($\sim$ 0.1 -- 0.4 GK), and thus the nuclear structure of $^{39}$Ca above the proton threshold (5770.92(63) keV), is necessary to resolve these contradictions. 
Purpose: The present study was performed to search for low-spin proton resonances in the $^{38}$K $+$ $p$ system, and to improve the uncertainties in energies of the known astrophysically significant proton resonances in $^{39}$Ca. 
Method: The level structure of $^{39}$Ca was investigated via high-resolution charged-particle spectroscopy with an Enge split-pole spectrograph using the $^{40}$Ca($^{3}$He, $\alpha$)$^{39}$Ca reaction. Differential cross sections were measured over 6 laboratory angles at 21 MeV. Distorted-wave Born approximation calculations were performed to constrain the spin-parity assignments of observed levels with special attention to those significant in determination of the $^{38}$K($p, \gamma$)$^{39}$Ca reaction rate over the nova temperature regime. 
Results: The resonance energies corresponding to two out of three astrophysically important states at 6154(5) and 6472.2(24) keV are measured with better precision than previous charged-particle spectroscopy measurements. A tentatively new state is discovered at 5908(3) keV. The spin-parity assignments of a few of the astrophysically important resonances are determined. 
Conclusions: The present $^{38}$K($p, \gamma$)$^{39}$Ca upper limit thermonuclear reaction rate at 0.1 -- 0.4 GK is higher than that determined in [Physical Review C 97 (2018) 025802] by at most a factor of 1.4 at 0.1 GK.}, number={5}, journal={PHYSICAL REVIEW C}, publisher={American Physical Society (APS)}, author={Setoodehnia, K. and Marshall, C. and Kelley, J. H. and Liang, J. and Chaves, F. Portillo and Longland, R.}, year={2018}, month={Nov} }
 @article{martin_josé_longland_2018, title={On the parallelization of stellar evolution codes}, volume={5}, DOI={10.1186/s40668-018-0025-5}, abstractNote={Abstract}, number={1}, journal={Computational Astrophysics and Cosmology}, publisher={Springer Nature}, author={Martin, David and José, Jordi and Longland, Richard}, year={2018}, month={Nov} }
 @article{longland_dermigny_marshall_2018, title={Reaction rates for the K-39(p, gamma)Ca-40 reaction}, volume={98}, ISSN={["2469-9993"]}, DOI={10.1103/PhysRevC.98.025802}, abstractNote={The magnesium-potassium anticorrelation observed in globular cluster NGC2419 can be explained by nuclear burning of hydrogen in hot environments. The exact site of this nuclear burning is, as yet, unknown. In order to constrain the sites responsible for this anticorrelation, the nuclear reactions involved must be well understood. The $^{39}\mathrm{K}+p$ reactions are one such pair of reactions. Here, we report a new evaluation of the $^{39}\mathrm{K}(p,\ensuremath{\gamma})^{40}\mathrm{Ca}$ reaction rate by taking into account ambiguities and measurement uncertainties in the nuclear data. The uncertainty in the $^{39}\mathrm{K}(p,\ensuremath{\gamma})^{40}\mathrm{Ca}$ reaction rate is larger than previously assumed, and its influence on nucleosynthesis models is demonstrated. We find the $^{39}\mathrm{K}(p,\ensuremath{\gamma})^{40}\mathrm{Ca}$ reaction cross section should be the focus of future experimental study to help constrain models aimed at explaining the magnesium-potassium anticorrelation in globular clusters.}, number={2}, journal={PHYSICAL REVIEW C}, publisher={American Physical Society (APS)}, author={Longland, R. and Dermigny, J. and Marshall, C.}, year={2018}, month={Aug} }
 @article{longland_2017, title={Correlated uncertainties in Monte Carlo reaction rate calculations}, volume={604}, url={https://doi.org/10.1051/0004-6361/201730911}, DOI={10.1051/0004-6361/201730911}, abstractNote={Context. Monte Carlo methods have enabled nuclear reaction rates from uncertain inputs to be presented in a statistically meaningful manner. However, these uncertainties are currently computed assuming no correlations between the physical quantities that enter those calculations. This is not always an appropriate assumption. Astrophysically important reactions are often dominated by resonances, whose properties are usually normalized to a well-known reference resonance. This insight provides a basis from which to develop a flexible framework for including correlations in Monte Carlo reaction rate calculations. Aims. The aim of this work is to develop and test a method for including correlations in Monte Carlo reaction rate calculations when the input has been normalized to a common reference. Methods. A mathematical framework is developed for including correlations between input parameters in Monte Carlo reaction rate calculations. The magnitude of those correlations is calculated from the uncertainties typically reported in experimental papers, where full correlation information is not available. The method is applied to four illustrative examples: a fictional 3-resonance reaction, $^{27}$Al(p,$\gamma$)$^{28}$Si, $^{23}$Na(p,$\alpha$)$^{20}$Ne, and $^{23}$Na($\alpha$,p)$^{26}$Al. Results. Reaction rates at low temperatures that are dominated by a few isolated resonances are found to minimally impacted by correlation effects. However, reaction rates determined from many overlapping resonances can be significantly affected. Uncertainties in the $^{23}$Na($\alpha$,p)$^{26}$Al reaction, for example, increase by up to a factor of 5. This highlights the need to take correlation effects into account in reaction rate calculations, and provide insight into which cases are expected to be most affected by them. The impact of correlation effects on nucleosynthesis is also investigated.}, journal={Astronomy & Astrophysics}, publisher={EDP Sciences}, author={Longland, Richard}, year={2017}, month={Jul}, pages={A34} }
 @article{hunt_iliadis_longland_2016, title={Characterization of a B-10-doped liquid scintillator as a capture-gated neutron spectrometer}, volume={811}, ISSN={["1872-9576"]}, DOI={10.1016/j.nima.2015.12.001}, abstractNote={We use a 250 MHz digitizer to characterize the pulse shape discrimination of a BC-523A 10B-doped liquid scintillator with capture-gating capabilities. Our results are compared to recent work claiming pulse shape discrimination between fast and thermal neutron signals. The capture event is identified, and we explain the origin of signals that are often misinterpreted. We use the time-of-flight method to measure the detector energy resolution for fast incident monoenergetic neutrons and the intrinsic neutron detection efficiency. Monte Carlo simulations are performed and we find agreement between measured and simulated results. These steps are important for understanding 10B-doped capture-gated spectroscopy in mixed radiation environments, as efficiencies using capture-gating are rarely reported in the literature.}, journal={NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT}, publisher={Elsevier BV}, author={Hunt, S. and Iliadis, C. and Longland, R.}, year={2016}, month={Mar}, pages={108–114} }
 @article{tain_jordán_agramunt_algora_bandac_bettini_caballero-folch_calviño_cano-ott_cortés_et al._2016, title={Measurement of very low (α,n) cross sections of astrophysical interest}, volume={665}, DOI={10.1088/1742-6596/665/1/012031}, abstractNote={The reactions 13C(α, n)16O and 22Ne(α, n)25Mg are the primary sources of neutrons for the astrophysical s-process. The feasibility of cross section measurements within the respective Gamow windows is discussed in quantitative terms for a 4π neutron counter, based on 3He tubes and a neutron moderator, placed in an underground lab.}, journal={Journal of Physics: Conference Series}, publisher={IOP Publishing}, author={Tain, J L and Jordán, D and Agramunt, J and Algora, A and Bandac, I and Bettini, A and Caballero-Folch, R and Calviño, F and Cano-Ott, D and Cortés, G and et al.}, year={2016}, month={Jan}, pages={012031} }
 @article{nsangu_laird_parikh_adsley_birch_chen_faestermann_fox_fulton_hertenberger_et al._2016, title={The20Ne(d,p)21Ne transfer reaction in relation to thes-process abundances}, volume={665}, DOI={10.1088/1742-6596/665/1/012026}, abstractNote={A study of the 20Ne(d,p)21Ne transfer reaction was performed using the Quadrupole Dipole Dipole Dipole (Q3D) magnetic spectrograph in Garching, Germany. The experiment probed excitation energies in 21Ne ranging from 6.9 MeV to 8.5 MeV. The aim was to investigate the spectroscopic information of 21Ne within the Gamow window of core helium burning in massive stars. Further information in this region will help reduce the uncertainties on the extrapolation down to Gamow window cross sections of the 17O(α,γ)21Ne reaction. In low metallicity stars, this reaction has a direct impact on s-process abundances by determining the fate of 16O as either a neutron poison or a neutron absorber. The experiment used a 22-MeV deuteron beam, with intensities varying from 0.5-1 μA, and an implanted target of 20Ne of 7 μg/cm2 in 40 μg/cm2 carbon foils. Sixteen 21Ne peaks have been identified in the Ex = 6.9-8.5 MeV range, of which only thirteen peaks correspond to known states. Only the previously-known Ex = 7.960 MeV state was observed within the Gamow window.}, journal={Journal of Physics: Conference Series}, publisher={IOP Publishing}, author={Nsangu, C T and Laird, A M and Parikh, A and Adsley, P and Birch, M D and Chen, A A and Faestermann, T and Fox, S P and Fulton, B R and Hertenberger, R and et al.}, year={2016}, month={Jan}, pages={012026} }
 @article{buckner_iliadis_kelly_downen_champagne_cesaratto_howard_longland_2015, title={High-intensity-beam study of O-17(p,gamma)F-18 and thermonuclear reaction rates for O-17 + p}, volume={91}, ISSN={["1089-490X"]}, DOI={10.1103/physrevc.91.015812}, abstractNote={Hydrogen burning of the oxygen isotopes takes place in low-mass stars, asymptotic giant branch stars, and classical novae. Observations of oxygen elemental and isotopic abundances in stellar spectra or in presolar grains provide strong constraints for stellar models if reliable thermonuclear reaction rates for hydrogen burning of oxygen are available. We present the results of a new measurement of the ${}^{17}\mathrm{O}{(p,\ensuremath{\gamma})}^{18}\mathrm{F}$ reaction in the laboratory bombarding energy range of $170--530$ keV. The measurement is performed with significantly higher beam intensities (${I}_{\mathrm{max}}$ $\ensuremath{\approx}$ 2 mA) compared to previous work and by employing a sophisticated $\ensuremath{\gamma}$-ray coincidence spectrometer. We measured the cross section at much lower energies than previous in-beam experiments. We also apply a novel data-analysis technique that is based on the decomposition of different contributions to the measured pulse-height spectrum. Our measured strengths of the low-energy resonances amount to $\ensuremath{\omega}{\ensuremath{\gamma}}_{\mathrm{pres}}(193\phantom{\rule{0.16em}{0ex}}\mathrm{keV})=(1.86\ifmmode\pm\else\textpm\fi{}0.13)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ eV and $\ensuremath{\omega}{\ensuremath{\gamma}}_{\mathrm{pres}}(518\phantom{\rule{0.16em}{0ex}}\mathrm{keV})=(13.70\ifmmode\pm\else\textpm\fi{}0.96)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ eV. For the direct capture $S$ factor at zero energy, we find a value of ${S}_{\mathrm{DC}}^{\mathrm{pres}}(0)$ = $4.82\ifmmode\pm\else\textpm\fi{}0.41$ keV b. We also present new thermonuclear rates for the ${}^{17}\mathrm{O}+p$ reactions, taking into account all consistent results from previous measurements.}, number={1}, journal={PHYSICAL REVIEW C}, publisher={American Physical Society (APS)}, author={Buckner, M. Q. and Iliadis, C. and Kelly, K. J. and Downen, L. N. and Champagne, A. E. and Cesaratto, J. M. and Howard, C. and Longland, R.}, year={2015}, month={Jan} }
 @article{coc_petitjean_uzan_vangioni_descouvemont_iliadis_longland_2015, title={New reaction rates for improved primordial D/H calculation and the cosmic evolution of deuterium}, volume={92}, ISSN={["1550-2368"]}, DOI={10.1103/physrevd.92.123526}, abstractNote={Primordial or big bang nucleosynthesis (BBN) is one of the three historically strong evidences for the big bang model. Standard BBN is now a parameter-free theory, since the baryonic density of the Universe has been deduced with an unprecedented precision from observations of the anisotropies of the cosmic microwave background radiation. There is a good agreement between the primordial abundances of He4, D, He3, and Li7 deduced from observations and from primordial nucleosynthesis calculations. However, the Li7 calculated abundance is significantly higher than the one deduced from spectroscopic observations and remains an open problem. In addition, recent deuterium observations have drastically reduced the uncertainty on D/H, to reach a value of 1.6%. It needs to be matched by BBN predictions whose precision is now limited by thermonuclear reaction rate uncertainties. This is especially important as many attempts to reconcile Li observations with models lead to an increased D prediction. Here, we reevaluate the d(p,γ)He3, d(d,n)He3, and d(d,p)H3 reaction rates that govern deuterium destruction, incorporating new experimental data and carefully accounting for systematic uncertainties. Contrary to previous evaluations, we use theoretical ab initio models for the energy dependence of the S factors. As a result, these rates increase at BBN temperatures, leading to a reduced value of D/H=(2.45±0.10)×10-5 (2σ), in agreement with observations.}, number={12}, journal={PHYSICAL REVIEW D}, publisher={American Physical Society (APS)}, author={Coc, Alain and Petitjean, Patrick and Uzan, Jean-Philippe and Vangioni, Elisabeth and Descouvemont, Pierre and Iliadis, Christian and Longland, Richard}, year={2015}, month={Dec} }
 @article{kelly_champagne_longland_buckner_2015, title={New recommended omega gamma for the E-r(c.m.)=458 keV resonance in Ne-22(p,gamma)Na-23}, volume={92}, ISSN={["1089-490X"]}, DOI={10.1103/physrevc.92.035805}, abstractNote={The ${E}_{r}^{\mathrm{c.m.}}=458$ keV resonance in $^{22}\mathrm{Ne}(p,\ensuremath{\gamma})^{23}\mathrm{Na}$ is an ideal reference resonance for measurements of cross sections and resonance strengths in noble gas targets. We report on a new measurement of the strength of this resonance. Data analysis employed the TFractionFitter class of root combined with geant simulations of potential decay cascades from this resonance. This approach allowed us to extract precise primary branching ratios for decays from the resonant state, including a new primary branch to the 7082-keV state in $^{23}\mathrm{Na}$. Our new resonance strength of $\ensuremath{\omega}\ensuremath{\gamma}$(458 keV) = 0.583(43) eV is more than $1\ensuremath{\sigma}$ higher than a recent high-precision result that relied on literature branching ratios.}, number={3}, journal={PHYSICAL REVIEW C}, publisher={American Physical Society (APS)}, author={Kelly, K. J. and Champagne, A. E. and Longland, R. and Buckner, M. Q.}, year={2015}, month={Sep} }
 @article{iliadis_longland_coc_timmes_champagne_2015, title={Statistical methods for thermonuclear reaction rates and nucleosynthesis simulations}, volume={42}, DOI={10.1088/0954-3899/42/3/034007}, abstractNote={Rigorous statistical methods for estimating thermonuclear reaction rates and 
nucleosynthesis are becoming increasingly established in nuclear astrophysics. 
The main challenge being faced is that experimental reaction rates are highly 
complex quantities derived from a multitude of different measured nuclear 
parameters (e.g., astrophysical S-factors, resonance energies and strengths, 
particle and γ-ray partial widths). We discuss the application of the Monte 
Carlo method to two distinct, but related, questions. First, given a set of 
measured nuclear parameters, how can one best estimate the resulting thermonuclear 
reaction rates and associated uncertainties? Second, given a set of 
appropriate reaction rates, how can one best estimate the abundances from 
nucleosynthesis (i.e., reaction network) calculations? The techniques described 
here provide probability density functions that can be used to derive statistically 
meaningful reaction rates and final abundances for any desired coverage 
probability. Examples are given for applications to s-process neutron sources, 
core-collapse supernovae, classical novae, and Big Bang nucleosynthesis.}, number={3}, journal={Journal of Physics G: Nuclear and Particle Physics}, publisher={IOP Publishing}, author={Iliadis, Christian and Longland, Richard and Coc, Alain and Timmes, F X and Champagne, Art E}, year={2015}, month={Feb}, pages={034007} }
 @article{champagne_iliadis_longland_2014, title={Nuclear astrophysics in the laboratory and in the universe}, volume={4}, DOI={10.1063/1.4864794}, abstractNote={Nuclear processes drive stellar evolution and so nuclear physics, stellar models and observations together allow us to describe the inner workings of stars and their life stories. This Information on nuclear reaction rates and nuclear properties are critical ingredients in addressing most questions in astrophysics and often the nuclear database is incomplete or lacking the needed precision. Direct measurements of astrophysically-interesting reactions are necessary and the experimental focus is on improving both sensitivity and precision. In the following, we review recent results and approaches taken at the Laboratory for Experimental Nuclear Astrophysics (LENA, http://research.physics.unc.edu/project/nuclearastro/Welcome.html).}, number={4}, journal={AIP Advances}, publisher={AIP Publishing}, author={Champagne, A. E. and Iliadis, C. and Longland, R.}, year={2014}, month={Apr}, pages={041006} }
 @article{longland_martin_josé_2014, title={Performance improvements for nuclear reaction network integration}, volume={563}, DOI={10.1051/0004-6361/201321958}, abstractNote={Aims. The aim of this work is to compare the performance of three reaction network integration methods used in stellar nucleosynthesis calculations. These are the Gear’s backward di erentiation method, Wagoner’s method (a 2nd-order Runge-Kutta method), and the Bader-Deuflehard semi-implicit multi-step method. Methods. To investigate the e ciency of each of the integration methods considered here, a test suite of temperature and density versus time profiles is used. This suite provides a range of situations ranging from constant temperature and density to the dramatically varying conditions present in white dwarf mergers, novae, and X-ray bursts. Some of these profiles are obtained separately from full hydrodynamic calculations. The integration e ciencies are investigated with respect to input parameters that constrain the desired accuracy and precision. Results. Gear’s backward di erentiation method is found to improve accuracy, performance, and stability in integrating nuclear reaction networks. For temperature-density profiles that vary strongly with time, it is found to outperform the Bader-Deuflehard method (although that method is very powerful for more smoothly varying profiles). Wagoner’s method, while relatively fast for many scenarios, exhibits hard-to-predict inaccuracies for some choices of integration parameters owing to its lack of error estimations.}, journal={Astronomy & Astrophysics}, publisher={EDP Sciences}, author={Longland, R. and Martin, D. and José, J.}, year={2014}, month={Mar}, pages={A67} }
 @article{mohr_longland_iliadis_2014, title={Thermonuclear reaction rate of Ne-18(alpha, p)Na-21 from Monte Carlo calculations}, volume={90}, ISSN={["1089-490X"]}, DOI={10.1103/physrevc.90.065806}, abstractNote={The $^{18}\mathrm{Ne}(\ensuremath{\alpha},p)^{21}\mathrm{Na}$ reaction impacts the break-out from the hot CNO cycles to the $rp$ process in type-I x-ray bursts. We present a revised thermonuclear reaction rate, which is based on the latest experimental data. The new rate is derived from Monte Carlo calculations, taking into account the uncertainties of all nuclear physics input quantities. In addition, we present the reaction rate uncertainty and probability density versus temperature. Our results are also consistent with estimates obtained using different indirect approaches.}, number={6}, journal={PHYSICAL REVIEW C}, publisher={American Physical Society (APS)}, author={Mohr, P. and Longland, R. and Iliadis, C.}, year={2014}, month={Dec} }
 @article{irvine_chen_parikh_setoodehnia_faestermann_hertenberger_wirth_bildstein_bishop_clark_et al._2013, title={Evidence for the existence of the astrophysically important 6.40-MeV state of31S}, volume={88}, DOI={10.1103/physrevc.88.055803}, abstractNote={Proton-unbound excited states of ${}^{31}$S have been populated with the ${}^{32}$S($d,t$)${}^{31}$S reaction at a beam energy of 24 MeV. Tritons corresponding to ${}^{31}$S states with ${E}_{x}{(}^{31}S)\ensuremath{\approx}6.3$--$7.1$ MeV were momentum analyzed with a high resolution quadrupole-dipole-dipole-dipole (Q3D) magnetic spectrograph at six angles ranging from ${\ensuremath{\theta}}_{\mathrm{lab}}={15}^{\ensuremath{\circ}}$ to $58.{5}^{\ensuremath{\circ}}$. We report a statistically significant detection of an astrophysically important state at ${E}_{x}{(}^{31}S)=6402$ (2) keV, whose existence as a third state in this region has been under debate. Using updated $A=31$ nuclear structure information, we present a new set of proposed ${}^{31}$S-${}^{31}$P mirror assignments for ${}^{31}$S, in which this state is tentatively assigned a spin of 7/2. This level, corresponding to a ${}^{30}$P + $p$ resonance at 271 keV, is likely to have a significant influence on the ${}^{30}$P($p,\ensuremath{\gamma}$)${}^{31}$S reaction rate in explosive hydrogen burning in classical novae.}, number={5}, journal={Physical Review C}, publisher={American Physical Society (APS)}, author={Irvine, D. and Chen, A. A. and Parikh, A. and Setoodehnia, K. and Faestermann, T. and Hertenberger, R. and Wirth, H.-F. and Bildstein, V. and Bishop, S. and Clark, J. A. and et al.}, year={2013}, month={Nov} }
 @article{laird_parikh_murphy_wimmer_chen_deibel_faestermann_fox_fulton_hertenberger_et al._2013, title={Isγ-Ray Emission from Novae Affected by Interference Effects in theF18(p,α)O15Reaction?}, volume={110}, DOI={10.1103/physrevlett.110.032502}, abstractNote={The (18)F(p,α)(15)O reaction rate is crucial for constraining model predictions of the γ-ray observable radioisotope (18)F produced in novae. The determination of this rate is challenging due to particular features of the level scheme of the compound nucleus, (19)Ne, which result in interference effects potentially playing a significant role. The dominant uncertainty in this rate arises from interference between J(π)=3/2(+) states near the proton threshold (S(p)=6.411 MeV) and a broad J(π)=3/2(+) state at 665 keV above threshold. This unknown interference term results in up to a factor of 40 uncertainty in the astrophysical S-factor at nova temperatures. Here we report a new measurement of states in this energy region using the (19)F((3)He,t)(19)Ne reaction. In stark contrast to previous assumptions we find at least 3 resonances between the proton threshold and E(cm)=50 keV, all with different angular distributions. None of these are consistent with J(π)=3/2(+) angular distributions. We find that the main uncertainty now arises from the unknown proton width of the 48 keV resonance, not from possible interference effects. Hydrodynamic nova model calculations performed indicate that this unknown width affects (18)F production by at least a factor of two in the model considered.}, number={3}, journal={Physical Review Letters}, publisher={American Physical Society (APS)}, author={Laird, A. M. and Parikh, A. and Murphy, A. St. J. and Wimmer, K. and Chen, A. A. and Deibel, C. M. and Faestermann, T. and Fox, S. P. and Fulton, B. R. and Hertenberger, R. and et al.}, year={2013}, month={Jan} }
 @article{pogrebnyak_howard_iliadis_longland_mitchell_2013, title={Mean proton and alpha-particle reduced widths of the Porter-Thomas distribution and astrophysical applications}, volume={88}, ISSN={["1089-490X"]}, DOI={10.1103/physrevc.88.015808}, abstractNote={The Porter-Thomas distribution is a key prediction of the Gaussian orthogonal ensemble in random matrix theory. It is routinely used to provide a measure for the number of levels that are missing in a given resonance analysis. The Porter-Thomas distribution is also of crucial importance for estimates of thermonuclear reaction 
rates where the contributions of certain unobserved resonances to the total reaction rate need to be taken into account. In order to estimate such contributions by randomly sampling over the Porter-Thomas distribution, 
the mean value of the reduced width must be known. We present mean reduced width values for protons and α particles of compound nuclei in the A = 28–67 mass range. The values are extracted from charged-particle 
elastic scattering and reaction data that weremeasured at the riangle Universities Nuclear Laboratory over several decades. Our new values differ significantly from those previously reported that were based on a preliminary analysis of a smaller data set. As an example for the application of our results, we present new thermonuclear rates for the 40Ca(α,γ)44Ti reaction, which is important for 44Ti production in core-collapse supernovae, and compare with previously reported results.}, number={1}, journal={PHYSICAL REVIEW C}, publisher={American Physical Society (APS)}, author={Pogrebnyak, I. and Howard, C. and Iliadis, C. and Longland, R. and Mitchell, G. E.}, year={2013}, month={Jul} }
 @article{cesaratto_champagne_buckner_clegg_daigle_howard_iliadis_longland_newton_oginni_2013, title={Measurement of theErc.m.=138keV resonance in the23Na(p,γ)24Mg reaction and the abundance of sodium in AGB stars}, volume={88}, DOI={10.1103/physrevc.88.065806}, abstractNote={Globular clusters represent some of the oldest stellar aggregations in the universe. As such, they are used as testing grounds for theories of stellar evolution and nucleosynthesis. Astronomical observations have shown star-to-star abundance variations in light-mass elements in all galactic globular clusters that are not predicted by standard stellar evolution models. In particular, there exists a pronounced anticorrelation between Na and O in the cluster stars that is not observed in field stars of similar evolutionary state. The abundance of Na is regulated in part by the ${}^{23}\mathrm{Na}$$+p$ reaction, which is also a bridge between the NeNa and the MgAl mass regions, but the ${}^{23}\mathrm{Na}{(p,\ensuremath{\gamma})}^{24}\mathrm{Mg}$ reaction rate is very uncertain for burning temperatures relevant to stars on the red giant and asymptotic giant branches. This uncertainty arises from an expected but unobserved resonance at ${E}_{r}^{\mathrm{c}.\mathrm{m}.}$ = 138 keV. The resonance strength upper limit has been determined to be $\ensuremath{\omega}\ensuremath{\gamma}$${}_{\mathrm{UL}}$(138 keV) $\ensuremath{\le}5.17\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$ eV with indications of a signal at the 90% confidence level. New reaction rates have been calculated for the ${}^{23}\mathrm{Na}{(p,\ensuremath{\gamma})}^{24}\mathrm{Mg}$ and ${}^{23}\mathrm{Na}{(p,\ensuremath{\alpha})}^{20}\mathrm{Ne}$ reactions and the recommended value for the ${}^{23}\mathrm{Na}{(p,\ensuremath{\gamma})}^{24}\mathrm{Mg}$ rate has been reduced by over an order of magnitude at ${T}_{9}$ = 0.07. This will have implications for the processing of material between the NeNa and MgAl mass regions.}, number={6}, journal={Physical Review C}, publisher={American Physical Society (APS)}, author={Cesaratto, J. M. and Champagne, A. E. and Buckner, M. Q. and Clegg, T. B. and Daigle, S. and Howard, C. and Iliadis, C. and Longland, R. and Newton, J. R. and Oginni, B. M.}, year={2013} }
 @article{setoodehnia_chen_kahl_komatsubara_josé_longland_abe_binh_chen_cherubini_et al._2013, title={Nuclear structure of30S and its implications for nucleosynthesis in classical novae}, volume={87}, DOI={10.1103/physrevc.87.065801}, abstractNote={The uncertainty in the 29P(p,gamma)30S reaction rate over the temperature range of 0.1 - 1.3 GK was previously determined to span ~4 orders of magnitude due to the uncertain location of two previously unobserved 3+ and 2+ resonances in the 4.7 - 4.8 MeV excitation region in 30S. Therefore, the abundances of silicon isotopes synthesized in novae, which are relevant for the identification of presolar grains of putative nova origin, were uncertain by a factor of 3. To investigate the level structure of 30S above the proton threshold (4394.9(7) keV), a charged-particle spectroscopy and an in-beam gamma-ray spectroscopy experiments were performed. Differential cross sections of the 32S(p,t)30S reaction were measured at 34.5 MeV. Distorted wave Born approximation calculations were performed to constrain the spin-parity assignments of the observed levels. An energy level scheme was deduced from gamma-gamma coincidence measurements using the 28Si(3He,n-gamma)30S reaction. Spin-parity assignments based on measurements of gamma-ray angular distributions and gamma-gamma directional correlation from oriented nuclei were made for most of the observed levels of 30S. As a result, the resonance energies corresponding to the excited states in 4.5 MeV - 6 MeV region, including the two astrophysically important states predicted previously, are measured with significantly better precision than before. The uncertainty in the rate of the 29P(p,gamma)30S reaction is substantially reduced over the temperature range of interest. Finally, the influence of this rate on the abundance ratios of silicon isotopes synthesized in novae are obtained via 1D hydrodynamic nova simulations.}, number={6}, journal={Physical Review C}, publisher={American Physical Society (APS)}, author={Setoodehnia, K. and Chen, A. A. and Kahl, D. and Komatsubara, T. and José, J. and Longland, R. and Abe, Y. and Binh, D. N. and Chen, J. and Cherubini, S. and et al.}, year={2013}, month={Jun} }
 @article{sala_haberl_josé_parikh_longland_pardo_andersen_2012, title={CONSTRAINTS ON THE MASS AND RADIUS OF THE ACCRETING NEUTRON STAR IN THE RAPID BURSTER}, volume={752}, ISSN={0004-637X 1538-4357}, url={http://dx.doi.org/10.1088/0004-637X/752/2/158}, DOI={10.1088/0004-637X/752/2/158}, abstractNote={The Rapid Burster (MXB 1730-335) is a unique object, showing both type I and type II X-ray bursts. A type I burst of the Rapid Burster was observed with Swift/X-Ray Telescope on 2009 March 5, showing photospheric radius expansion (PRE) for the first time in this source. We report here on the mass and radius determination from this PRE burst using a Bayesian approach. After marginalization over the likely distance of the system (5.8–10 kpc), we obtain M = 1.1 ± 0.3 M☉ and R = 9.6 ± 1.5 km (1σ uncertainties) for the compact object, ruling out the stiffest equations of state for the neutron star. We study the sensitivity of the results to the distance, the color correction factor, and the hydrogen mass fraction in the envelope. We find that only the distance plays a crucial role.}, number={2}, journal={The Astrophysical Journal}, publisher={IOP Publishing}, author={Sala, G. and Haberl, F. and José, J. and Parikh, A. and Longland, R. and Pardo, L. C. and Andersen, M.}, year={2012}, month={Jun}, pages={158} }
 @article{longland_iliadis_2012, title={Current Status of the22Ne+αs-Process Neutron Source}, volume={337}, DOI={10.1088/1742-6596/337/1/012047}, abstractNote={The reaction rates of the s-process neutron producing 22Ne(α,n)25Mg reaction and its competing 22Ne(α, γ)26Mg reaction are needed to accurately predict nucleosynthesis in massive stars and Asymptotic Giant Branch stars. Here, we present a re-evaluation of the reaction rates by incorporating recent data and by using a Monte Carlo uncertainty propagation method. The effect of those results on nucleosynthesis in massive stars is studied. We show that our new rates lead to similar final abundances, but with significantly reduced uncertainties in comparison to literature rates.}, journal={Journal of Physics: Conference Series}, publisher={IOP Publishing}, author={Longland, Richard and Iliadis, Christian}, year={2012}, month={Feb}, pages={012047} }
 @article{longland_lorén-aguilar_josé_garcía-berro_althaus_2012, title={Lithium production in the merging of white dwarf stars}, volume={542}, DOI={10.1051/0004-6361/201219289}, abstractNote={The origin of R Coronae Borealis stars has been elusive for over 200 years. Currently, two theories for their formation have been presented. These are the Final Flash scenario, in which a dying asymptotic giant branch (AGB) star throws o its atmosphere to reveal the hydrogen poor, heavily processed material underneath, and the double degenerate scenario, in which two white dwarfs merge to produce a new star with renewed vigour. Some theories predict that the temperatures reached during the latter scenario would destroy any lithium originally present in the white dwarfs. The observed lithium content of some R Coronae Borealis stars, therefore, is often interpreted as an indication that the Final Flash scenario best describes their formation. In this paper, it is shown that lithium production can, indeed, occur in the merging of a helium white dwarf with a carbon-oxygen white dwarf if their chemical composition, particularly that of 3 He, is fully considered. The production mechanism is described in detail, and the sensitivity of lithium production to the merger environment is investigated. Nucleosynthesis post-processing calculations of smoothed-particle hydrodynamics (SPH) tracer particles are performed to show that any lithium produced in these environments will be concentrated towards the cloud of material surrounding the R CrB star. Measurements of the lithium content of these clouds would, therefore, provide a valuable insight into the formation mechanism of R CrB stars.}, journal={Astronomy & Astrophysics}, publisher={EDP Sciences}, author={Longland, R. and Lorén-Aguilar, P. and José, J. and García-Berro, E. and Althaus, L. G.}, year={2012}, month={Jun}, pages={A117} }
 @article{longland_iliadis_karakas_2012, title={Publisher's Note: Reaction rates for thes-process neutron source22Ne +α[Phys. Rev. C85, 065809 (2012)]}, volume={86}, DOI={10.1103/physrevc.86.019903}, number={1}, journal={Physical Review C}, publisher={American Physical Society (APS)}, author={Longland, R. and Iliadis, C. and Karakas, A. I.}, year={2012}, month={Jul} }
 @article{longland_iliadis_karakas_2012, title={Reaction rates for thes-process neutron source22Ne+α}, volume={85}, DOI={10.1103/physrevc.85.065809}, abstractNote={The 22Ne(α, n)25Mg reaction is an important source of neutrons for the s-process. In massive stars responsible for the weak component of the s-process, 22Ne(α, n)25Mg is the dominant source of neutrons, both during core helium burning and in carbon-shell burning. For the main s-process component produced in asymptotic giant branch (AGB) stars, the 13C(α, n)16O reaction is the dominant source of neutrons operating during the interpulse period, with the 22Ne + α source affecting mainly the s-process branchings during a thermal pulse. Rate uncertainties in the competing 22Ne(α, n)25Mg and 22Ne(α, γ)26Mg reactions result in large variations of s-process nucleosynthesis. Here, we present up-to-date and statistically rigorous 22Ne + α reaction rates using recent experimental results and Monte Carlo sampling. Our new rates are used in postprocessing nucleosynthesis calculations both for massive stars and AGB stars. We demonstrate that the nucleosynthesis uncertainties arising from the new rates are dramatically reduced in comparison to previously published results, but several ambiguities in the present data must still be addressed. Recommendations for further study to resolve these issues are provided.}, number={6}, journal={Physical Review C}, publisher={American Physical Society (APS)}, author={Longland, R. and Iliadis, C. and Karakas, A. I.}, year={2012}, month={Jun} }
 @article{longland_2012, title={Recommendations for Monte Carlo nucleosynthesis sampling}, volume={548}, DOI={10.1051/0004-6361/201220386}, abstractNote={Context. Recent reaction rate evaluations include reaction rate uncertainties that have been determined in a statistically meaningful manner. Furthermore, reaction rate probability density distributions have been determined and published in the form of lognormal parameters with the specific goal of pursuing Monte Carlo nucleosynthesis studies. Aims. A variety of methods is available for randomly sampling over reaction rate probability densities. The aim of this work is to investigate these methods and determine the most accurate method for estimating elemental abundance uncertainties. Methods. Experimental Monte Carlo reaction rates are first computed for the 22 Ne+ , 20 Ne(p, ) 21 Na, 25 Mg(p, ) 26 Al, and 18 F(p, ) 15 O reactions, which are used to calculate reference nucleosynthesis yields for 16 nuclei a ected by nucleosynthesis in massive stars and classical novae. Five di erent methods of randomly sampling over these reaction rate probability distributions are then developed, tested, and compared with the reference nucleosynthesis yields. Results. Given that the reaction rate probability density distributions can be described accurately with a lognormal distribution, Monte Carlo nucleosynthesis variations arising from the parametrised estimates for the reaction rate variations agree remarkably well with those obtained from the true rate samples. Most significantly, the most simple parametrisation agrees within just a few percent, meaning that Monte Carlo nucleosynthesis studies can be performed reliably using lognormal parametrisations of reaction rate probability density functions.}, journal={Astronomy & Astrophysics}, publisher={EDP Sciences}, author={Longland, R.}, year={2012}, month={Nov}, pages={A30} }
 @article{parikh_wimmer_faestermann_hertenberger_josé_longland_wirth_bildstein_bishop_chen_et al._2011, title={Improving theP30(p,γ)S31rate in oxygen-neon novae: Constraints onJπvalues for proton-threshold states inS31}, volume={83}, DOI={10.1103/physrevc.83.045806}, abstractNote={Calculation of the thermonuclear {sup 30}P(p,{gamma}){sup 31}S rate in oxygen-neon nova explosions depends critically upon nuclear structure information for states within {approx}600 keV of the {sup 30}P+p threshold in {sup 31}S. We have studied the {sup 31}P({sup 3}He,t){sup 31}S reaction at 25 MeV using a high-resolution quadrupole-dipole-dipole-dipole magnetic spectrograph. Tritons corresponding to the states E{sub x}({sup 31}S) {approx} 6.1-7.1 MeV were observed at ten angles between {theta}{sub lab} = 10 deg. and 55 deg. States that were only tentatively identified in past studies have been observed unambiguously. For the first time, we have measured and analyzed angular distributions of the {sup 31}P({sup 3}He,t){sup 31}S reaction. We present, also for the first time, a consistent set of experimental spin constraints for all except one of the critical proton-threshold states in {sup 31}S. Hydrodynamic nova simulations have been calculated in order to assess the impact on nova nucleosynthesis of remaining uncertainties in J{sup {pi}} values of {sup 31}S states and the unknown relevant proton spectroscopic factors. We find that these uncertainties may lead to a factor of up to 20 variation in the {sup 30}P(p,{gamma}){sup 31}S rate over typical nova peak temperatures, which may then lead to a factor of up tomore » 4 variation in the nova yields of Si-Ar isotopes.« less}, number={4}, journal={Physical Review C}, publisher={American Physical Society (APS)}, author={Parikh, A. and Wimmer, K. and Faestermann, T. and Hertenberger, R. and José, J. and Longland, R. and Wirth, H.-F. and Bildstein, V. and Bishop, S. and Chen, A. A. and et al.}, year={2011}, month={Apr} }
 @article{longland_lorén-aguilar_josé_garcía-berro_althaus_isern_2011, title={NUCLEOSYNTHESIS DURING THE MERGER OF WHITE DWARFS AND THE ORIGIN OF R CORONAE BOREALIS STARS}, volume={737}, DOI={10.1088/2041-8205/737/2/l34}, abstractNote={Many hydrogen-deficient stars are characterized by surface abundance patterns that are hard to reconcile with conventional stellar evolution. Instead, it has been suggested that they may represent the result of a merger episode between a helium and a carbon–oxygen white dwarf. In this Letter, we present a nucleosynthesis study of the merger of a 0.4 M☉ helium white dwarf with a 0.8 M☉ carbon–oxygen white dwarf, by coupling the thermodynamic history of Smoothed Particle Hydrodynamics particles with a post-processing code. The resulting chemical abundance pattern, particularly for oxygen and fluorine, is in qualitative agreement with the observed abundances in R Coronae Borealis stars.}, number={2}, journal={The Astrophysical Journal}, publisher={IOP Publishing}, author={Longland, R. and Lorén-Aguilar, P. and José, J. and García-Berro, E. and Althaus, L. G. and Isern, J.}, year={2011}, month={Aug}, pages={L34} }
 @article{longland_iliadis_champagne_newton_ugalde_coc_fitzgerald_2010, title={Charged-particle thermonuclear reaction rates: I. Monte Carlo method and statistical distributions}, volume={841}, DOI={10.1016/j.nuclphysa.2010.04.008}, abstractNote={A method based on Monte Carlo techniques is presented for evaluating thermonuclear reaction rates. We begin by reviewing commonly applied procedures and point out that reaction rates that have been reported up to now in the literature have no rigorous statistical meaning. Subsequently, we associate each nuclear physics quantity entering in the calculation of reaction rates with a specific probability density function, including Gaussian, lognormal and chi-squared distributions. Based on these probability density functions the total reaction rate is randomly sampled many times until the required statistical precision is achieved. This procedure results in a median (Monte Carlo) rate which agrees under certain conditions with the commonly reported recommended "classical" rate. In addition, we present at each temperature a low rate and a high rate, corresponding to the 0.16 and 0.84 quantiles of the cumulative reaction rate distribution. These quantities are in general different from the statistically meaningless "minimum" (or "lower limit") and "maximum" (or "upper limit") reaction rates which are commonly reported. Furthermore, we approximate the output reaction rate probability density function by a lognormal distribution and present, at each temperature, the lognormal parameters miu and sigma. The values of these quantities will be crucial for future Monte Carlo nucleosynthesis studies. Our new reaction rates, appropriate for bare nuclei in the laboratory, are tabulated in the second paper of this series (Paper II). The nuclear physics input used to derive our reaction rates is presented in the third paper of this series (Paper III). In the fourth paper of this series (Paper IV) we compare our new reaction rates to previous results.}, number={1-4}, journal={Nuclear Physics A}, publisher={Elsevier BV}, author={Longland, R. and Iliadis, C. and Champagne, A.E. and Newton, J.R. and Ugalde, C. and Coc, A. and Fitzgerald, R.}, year={2010}, month={Oct}, pages={1–30} }
 @article{iliadis_longland_champagne_coc_fitzgerald_2010, title={Charged-particle thermonuclear reaction rates: II. Tables and graphs of reaction rates and probability density functions}, volume={841}, DOI={10.1016/j.nuclphysa.2010.04.009}, abstractNote={Numerical values of charged-particle thermonuclear reaction rates for nuclei in the A=14 to 40 region are tabulated. The results are obtained using a method, based on Monte Carlo techniques, that has been described in the preceding paper of this issue (Paper I). We present a low rate, median rate and high rate which correspond to the 0.16, 0.50 and 0.84 quantiles, respectively, of the cumulative reaction rate distribution. The meaning of these quantities is in general different from the commonly reported, but statistically meaningless expressions, “lower limit”, “nominal value” and “upper limit” of the total reaction rate. In addition, we approximate the Monte Carlo probability density function of the total reaction rate by a lognormal distribution and tabulate the lognormal parameters μ and σ at each temperature. We also provide a quantitative measure (Anderson–Darling test statistic) for the reliability of the lognormal approximation. The user can implement the approximate lognormal reaction rate probability density functions directly in a stellar model code for studies of stellar energy generation and nucleosynthesis. For each reaction, the Monte Carlo reaction rate probability density functions, together with their lognormal approximations, are displayed graphically for selected temperatures in order to provide a visual impression. Our new reaction rates are appropriate for bare nuclei in the laboratory. The nuclear physics input used to derive our reaction rates is presented in the subsequent paper of this issue (Paper III). In the fourth paper of this issue (Paper IV) we compare our new reaction rates to previous results.}, number={1-4}, journal={Nuclear Physics A}, publisher={Elsevier BV}, author={Iliadis, C. and Longland, R. and Champagne, A.E. and Coc, A. and Fitzgerald, R.}, year={2010}, month={Oct}, pages={31–250} }
 @article{iliadis_longland_champagne_coc_2010, title={Charged-particle thermonuclear reaction rates: III. Nuclear physics input}, volume={841}, DOI={10.1016/j.nuclphysa.2010.04.010}, abstractNote={The nuclear physics input used to compute the Monte Carlo reaction rates and probability density functions that are tabulated in the second paper of this series (Paper II) is presented. Specifically, we publish the input files to the Monte Carlo reaction rate code RatesMC, which is based on the formalism presented in the first paper of this series (Paper I). This data base contains overwhelmingly experimental nuclear physics information. The survey of literature for this review was concluded in November 2009.}, number={1-4}, journal={Nuclear Physics A}, publisher={Elsevier BV}, author={Iliadis, C. and Longland, R. and Champagne, A.E. and Coc, A.}, year={2010}, month={Oct}, pages={251–322} }
 @article{iliadis_longland_champagne_coc_2010, title={Charged-particle thermonuclear reaction rates: IV. Comparison to previous work}, volume={841}, DOI={10.1016/j.nuclphysa.2010.04.012}, abstractNote={We compare our Monte Carlo reaction rates (see Paper II of this issue) to previous results that were obtained by using the classical method of computing thermonuclear reaction rates. For each reaction, the comparison is presented using two types of graphs: the first shows the change in reaction rate uncertainties, while the second displays our new results normalized to the previously recommended reaction rate. We find that the rates have changed significantly for almost all reactions considered here. The changes are caused by (i) our new Monte Carlo method of computing reaction rates (see Paper I of this issue), and (ii) newly available nuclear physics information (see Paper III of this issue).}, number={1-4}, journal={Nuclear Physics A}, publisher={Elsevier BV}, author={Iliadis, C. and Longland, R. and Champagne, A.E. and Coc, A.}, year={2010}, month={Oct}, pages={323–388} }
 @article{newton_iliadis_champagne_cesaratto_daigle_longland_2010, title={Measurement ofO17(p,γ)F18between the narrow resonances atErlab=193and519 keV}, volume={81}, DOI={10.1103/physrevc.81.045801}, abstractNote={The $^{17}\mathrm{O}$($p,\ensuremath{\gamma}$)$^{18}\mathrm{F}$ reaction sensitively influences hydrogen burning nucleosynthesis in a number of stellar sites, including classical novae. These thermonuclear explosions, taking place in close binary star systems, produce peak temperatures in the range of $T=100--400$ MK. Recent results indicate that the thermonuclear rates for this reaction in this particular temperature range are dominated by the direct capture process. We report on the measurement of the $^{17}\mathrm{O}$($p,\ensuremath{\gamma}$)$^{18}\mathrm{F}$ cross section between the narrow resonances at ${E}_{r}^{\mathrm{lab}}=193$ and $519$ keV, where the $S$ factor is expected to vary smoothly with energy. We extract the direct capture contribution from the total cross section and demonstrate that earlier data are inconsistent with our results.}, number={4}, journal={Physical Review C}, publisher={American Physical Society (APS)}, author={Newton, J. R. and Iliadis, C. and Champagne, A. E. and Cesaratto, J. M. and Daigle, S. and Longland, R.}, year={2010}, month={Apr} }
 @inproceedings{coc_iliadis_longland_champagne_fitzgerald_susa_arnould_gales_motobayashi_scheidenberger_et al._2010, title={Monte-Carlo Reaction Rate Evaluation for Astrophysics}, url={http://dx.doi.org/10.1063/1.3455927}, DOI={10.1063/1.3455927}, abstractNote={We present a new evaluation of thermonuclear reaction rates for astrophysics involving proton and α‐particle induced reactions, in the target mass range between A = 14 and 40, including many radioactive targets. A method based on Monte Carlo techniques is used to evaluate thermonuclear reaction rates and their uncertainties. At variance with previous evaluations, the low, median and high rates are statistically defined and a lognormal approximation to the rate distribution is given. This provides improved input for astrophysical model calculations using also the Monte Carlo method to estimate uncertainties on isotopic abundances.}, publisher={AIP}, author={Coc, A. and Iliadis, C. and Longland, R. and Champagne, A. E. and Fitzgerald, R. and Susa, Hajime and Arnould, Marcel and Gales, Sydney and Motobayashi, Tohru and Scheidenberger, Christoph and et al.}, year={2010} }
 @article{deboer_wiescher_görres_longland_iliadis_rusev_tonchev_2010, title={Photoexcitation of astrophysically important states inMg26. II. Ground-state-transition partial widths}, volume={82}, DOI={10.1103/physrevc.82.025802}, abstractNote={The level structure of 26 Mg near the neutron-separation energy, which is of interest for s-process nucleosynthesis, was studied at the High Intensity Gamma-Ray Source of the Triangle Universities Nuclear Laboratory using the method of nuclear resonance fluorescence. A nearly monoenergetic and linearly polarized γ-ray beam was used to scan the excitation energy range from 10.5 to 11.7 MeV. For the five states observed, the total widths and partial widths are determined. Precise measurement of these widths is necessary for the prediction of neutron production for the s-process.}, number={2}, journal={Physical Review C}, publisher={American Physical Society (APS)}, author={deBoer, R. J. and Wiescher, M. and Görres, J. and Longland, R. and Iliadis, C. and Rusev, G. and Tonchev, A. P.}, year={2010}, month={Aug} }
 @article{carson_iliadis_cesaratto_champagne_downen_ivanovic_kelley_longland_newton_rusev_et al._2010, title={Ratio of germanium detector peak efficiencies at photon energies of 4.4 and 11.7 MeV: Experiment versus simulation}, volume={618}, ISSN={["1872-9576"]}, DOI={10.1016/j.nima.2010.02.128}, abstractNote={Full-energy peak efficiencies of germanium detectors are frequently investigated at γ-ray energies below 4 MeV using calibrated radioactive sources, while very accurate peak efficiencies for higher photon energies are essentially non-existent. Peak efficiencies in the energy range of Eγ=4–12MeV are crucial for a number of applications, including nuclear astrophysics measurements of fusion reactions and resonance fluorescence experiments. We report on a novel method, using the 163 keV resonance in the B11(p,γ)C12 reaction, of measuring accurately the ratio of full-energy peak efficiencies at 4.44 and 11.66 MeV. We derive this ratio for three different detector-target distances (3, 12 and 26 cm) directly from measured peak intensities and demonstrate that corrections are small (γ-ray branching ratios, angular correlations, coincidence summing). Our measured full-energy peak efficiency ratios have a precision of 1.4–1.6%. Another important goal of our study was to determine to what precision full-energy peak efficiencies at high γ-ray energies can be predicted using the simulation codes Geant3 and Geant4. We imaged our detector using computed tomography and radiographs in order to extract reliable detector crystal dimensions. Based on these results, extensive computer simulations are performed. We find that the simulation results agree with the measured peak efficiency ratios within an uncertainty of 1.6% for Geant4 and 2.6% for Geant3. Our results are useful for assigning uncertainties when peak efficiencies are extrapolated from low energy data to high energies based on simulations only.}, number={1-3}, journal={NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT}, publisher={Elsevier BV}, author={Carson, Spencer and Iliadis, Christian and Cesaratto, John and Champagne, Art and Downen, Lori and Ivanovic, Marija and Kelley, John and Longland, Richard and Newton, Joseph R. and Rusev, Gencho and et al.}, year={2010}, month={Jun}, pages={190–198} }
 @article{longland_iliadis_cesaratto_champagne_daigle_newton_fitzgerald_2010, title={Resonance strength inNe22(p,γ)Na23from depth profiling in aluminum}, volume={81}, DOI={10.1103/physrevc.81.055804}, abstractNote={A novel method for extracting absolute resonance strengths has been investigated. By implanting $^{22}\mathrm{Ne}$ ions into a thick aluminum backing and simultaneously measuring the $^{22}\mathrm{Ne}$$+p$ and $^{27}\mathrm{Al}$$+p$ reactions, the strength of the ${E}_{r}^{\mathrm{lab}}=479$ keV resonance in $^{22}\mathrm{Ne}$($p$,$\ensuremath{\gamma}$)$^{23}\mathrm{Na}$ was determined to be $\ensuremath{\omega}\ensuremath{\gamma}=0.524(51)$ eV. This result has significantly reduced uncertainties compared to earlier work. Our results are important for the absolute normalizations of resonance strengths in the $^{22}\mathrm{Ne}$($p$,$\ensuremath{\gamma}$)$^{23}\mathrm{Na}$ hydrogen-burning reaction and in the $^{22}\mathrm{Ne}$$+\ensuremath{\alpha} s$-process neutron-source reactions.}, number={5}, journal={Physical Review C}, publisher={American Physical Society (APS)}, author={Longland, R. and Iliadis, C. and Cesaratto, J. M. and Champagne, A. E. and Daigle, S. and Newton, J. R. and Fitzgerald, R.}, year={2010}, month={May} }
 @article{longland_iliadis_rusev_tonchev_deboer_görres_wiescher_2009, title={Photoexcitation of astrophysically important states inMg26}, volume={80}, DOI={10.1103/physrevc.80.055803}, abstractNote={We performed a nuclear resonance fluorescence experiment to determine the energy and quantum numbers of excited states in {sup 26}Mg. Spin-parity ambiguities of excited states in {sup 26}Mg, the compound nucleus for the s-process neutron source {sup 22}Ne({alpha},n){sup 25}Mg, result in large uncertainties in the reaction rates. The present work uses the monoenergetic {gamma}-ray beam from the High-Intensity {gamma}-ray Source to probe states in the excitation energy range of E{sub x}=10.8 to 11.4 MeV. Five excited states were observed and unambiguous quantum numbers were assigned at E{sub x}=10 573.3(8) keV (J{sup {pi}}=1{sup -}), E{sub x}=10 647.3(8) keV (J{sup {pi}}=1{sup +}), E{sub x}=10 805.7(7) keV (J{sup {pi}}=1{sup -}), E{sub x}=10 949.1(8) keV (J{sup {pi}}=1{sup -}), and E{sub x}=11 153.5(10) keV (J{sup {pi}}=1{sup +}). The two natural parity states, located between the {alpha}-particle and neutron thresholds, are expected to significantly influence the rate of the competing {sup 22}Ne({alpha},{gamma}){sup 26}Mg reaction. An important finding of this work is that the E{sub x}=11 154 keV level has unnatural parity, contrary to previous results, and thus does not contribute to the {sup 22}Ne+{alpha} reaction rates.}, number={5}, journal={Physical Review C}, publisher={American Physical Society (APS)}, author={Longland, R. and Iliadis, C. and Rusev, G. and Tonchev, A. P. and deBoer, R. J. and Görres, J. and Wiescher, M.}, year={2009}, month={Nov} }
 @article{gintautas_champagne_kondev_longland_2009, title={Thermal equilibration ofLu176viaKmixing}, volume={80}, DOI={10.1103/physrevc.80.015806}, abstractNote={In astrophysical environments, the long-lived (\T_1/2 = 37.6 Gy) ground state of 176-Lu can communicate with a short-lived (T_1/2 = 3.664 h) isomeric level through thermal excitations. Thus, the lifetime of 176-Lu in an astrophysical environment can be quite different than in the laboratory. We examine the possibility that the rate of equilibration can be enhanced via K-mixing of two levels near E_x = 725 keV and estimate the relevant gamma-decay rates. We use this result to illustrate the effect of K-mixing on the effective stellar half-life. We also present a network calculation that includes the equilibrating transitions allowed by K-mixing. Even a small amount of K-mixing will ensure that 176-Lu reaches at least a quasi-equilibrium during an s-process triggered by the 22-Ne neutron source.}, number={1}, journal={Physical Review C}, publisher={American Physical Society (APS)}, author={Gintautas, Vadas and Champagne, Arthur E. and Kondev, Filip G. and Longland, Richard}, year={2009}, month={Jul} }
 @article{newton_longland_iliadis_2008, title={Matching of experimental and statistical-model thermonuclear reaction rates at high temperatures}, volume={78}, DOI={10.1103/physrevc.78.025805}, abstractNote={We address the problem of extrapolating experimental thermonuclear reaction rates toward high stellar temperatures (T>1 GK) by using statistical model (Hauser-Feshbach) results. Reliable reaction rates at such temperatures are required for studies of advanced stellar burning stages, supernovae, and x-ray bursts. Generally accepted methods are based on the concept of a Gamow peak. We follow recent ideas that emphasized the fundamental shortcomings of the Gamow peak concept for narrow resonances at high stellar temperatures. Our new method defines the effective thermonuclear energy range (ETER) by using the 8th, 50th, and 92nd percentiles of the cumulative distribution of fractional resonant reaction rate contributions. This definition is unambiguous and has a straightforward probability interpretation. The ETER is used to define a temperature at which Hauser-Feshbach rates can be matched to experimental rates. This matching temperature is usually much higher compared to previous estimates that employed the Gamow peak concept. We suggest that an increased matching temperature provides more reliable extrapolated reaction rates since Hauser-Feshbach results are more trustwhorthy the higher the temperature. Our ideas are applied to 21 (p,{gamma}), (p,{alpha}), and ({alpha},{gamma}) reactions on A=20-40 target nuclei. For many of the cases studied here, our extrapolated reaction rates at high temperatures differmore » significantly from those obtained using the Gamow peak concept.« less}, number={2}, journal={Physical Review C}, publisher={American Physical Society (APS)}, author={Newton, J. R. and Longland, R. and Iliadis, C.}, year={2008}, month={Aug} }
 @article{ugalde_champagne_daigle_iliadis_longland_newton_osenbaugh-stewart_clark_deibel_parikh_et al._2007, title={Experimental evidence for a natural parity state inMg26and its impact on the production of neutrons for thesprocess}, volume={76}, DOI={10.1103/physrevc.76.025802}, abstractNote={We have studied natural parity states in {sup 26}Mg via the {sup 22}Ne({sup 6}Li, d){sup 26}Mg reaction. Our method significantly improves the energy resolution of previous experiments and, as a result, we report the observation of a natural parity state in {sup 26}Mg. Possible spin-parity assignments are suggested on the basis of published {gamma}-ray decay experiments. The stellar rate of the {sup 22}Ne({alpha},{gamma}){sup 26}Mg reaction is reduced and may give rise to an increase in the production of s-process neutrons via the {sup 22}Ne({alpha},n){sup 25}Mg reaction.}, number={2}, journal={Physical Review C}, publisher={American Physical Society (APS)}, author={Ugalde, C. and Champagne, A. E. and Daigle, S. and Iliadis, C. and Longland, R. and Newton, J. R. and Osenbaugh-Stewart, E. and Clark, J. A. and Deibel, C. and Parikh, A. and et al.}, year={2007}, month={Aug} }
 @article{newton_iliadis_champagne_longland_ugalde_2007, title={Remeasurement of the 193 keV resonance inO17(p,α)N14}, volume={75}, DOI={10.1103/physrevc.75.055808}, abstractNote={A recently discovered resonance at 193 keV determines the thermonuclear rates of the {sup 17}O +p reactions at temperatures important for the nucleosynthesis in classical novae (T=0.1-0.4 GK). We report on a remeasurement of this resonance in the {sup 17}O(p,{alpha}){sup 14}N reaction by using a different kind of target compared to the previous study. Special emphasis is placed on Monte Carlo simulations of the experiment in order to better understand certain effects that have been disregarded previously. Our measured value of the resonance strength amounts to ({omega}{gamma}){sub p{alpha}}=(1.66{+-}0.17)x10{sup -3} eV, in agreement with the previously reported result. As a byproduct of our study, we find that the inhomogeneity of the foil placed in front of the {alpha}-particle detector determines the resolution in the pulse-height spectrum, and thus constrains the signal-to-noise ratio in searches of very weak (p,{alpha}) resonances.}, number={5}, journal={Physical Review C}, publisher={American Physical Society (APS)}, author={Newton, J. R. and Iliadis, C. and Champagne, A. E. and Longland, R. and Ugalde, C.}, year={2007}, month={May} }
 @article{longland_iliadis_champagne_fox_newton_2006, title={Nuclear astrophysics studies at the LENA facility: The -ray detection system}, volume={566}, DOI={10.1016/j.nima.2006.07.006}, abstractNote={The detection system of The Laboratory for Experimental Nuclear Astrophysics is described, including methods for measuring weak capture-γ-ray resonances. Improved γγ-coincidence techniques are detailed, as well as the reduction of cosmic muon-induced background in the energy region of Eγ=0.6–9.0MeV by the use of compact cosmic muon anti-coincidence shields. These techniques reduced background count rates in the regions of Eγ=0.6–3.0 and 3.0–9.0 MeV with respect to unshielded singles count rates by factors of 3600 and 21, respectively.}, number={2}, journal={Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment}, publisher={Elsevier BV}, author={Longland, R. and Iliadis, C. and Champagne, A.E. and Fox, C. and Newton, J.R.}, year={2006}, month={Oct}, pages={452–464} }
 @article{fox_iliadis_champagne_fitzgerald_longland_newton_pollanen_runkle_2005, title={Thermonuclear reaction rate ofO17(p,γ)F18}, volume={71}, DOI={10.1103/physrevc.71.055801}, abstractNote={The $^{17}\mathrm{O}(p,\ensuremath{\gamma})^{18}\mathrm{F}$ and $^{17}\mathrm{O}(p,\ensuremath{\alpha})^{14}\mathrm{N}$ reactions have a profound influence on hydrogen-burning nucleosynthesis in a number of stellar sites, including red giants, asymptotic giant branch (AGB) stars, massive stars, and classical novae. Previously evaluated thermonuclear rates for both reactions carry large uncertainties. We investigated the proton-capture reaction on $^{17}\mathrm{O}$ in the bombarding energy range of ${E}_{p}^{\mathrm{lab}}\phantom{\rule{0.3em}{0ex}}=\phantom{\rule{0.3em}{0ex}}180\text{\ensuremath{-}}540\phantom{\rule{0.3em}{0ex}}\text{keV}$. We observed a previously undiscovered resonance at ${E}_{R}^{\mathrm{lab}}\phantom{\rule{0.3em}{0ex}}=\phantom{\rule{0.3em}{0ex}}193.2\phantom{\rule{0.3em}{0ex}}\ifmmode\pm\else\textpm\fi{}\phantom{\rule{0.3em}{0ex}}0.9\phantom{\rule{0.3em}{0ex}}\text{keV}$. The resonance strength amounts to $(\ensuremath{\omega}\ensuremath{\gamma}){}_{p\ensuremath{\gamma}}=\phantom{\rule{0.3em}{0ex}}(1.2\ifmmode\pm\else\textpm\fi{}0.2)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. With this value, the uncertainties of the $^{17}\mathrm{O}(p,\ensuremath{\gamma})^{18}\mathrm{F}$ reaction rates are reduced by orders of magnitude in the peak temperature range of classical novae $(T=0.1\text{\ensuremath{-}}0.4\phantom{\rule{0.3em}{0ex}}\mathrm{GK})$. We also report on a reevaluation of the $^{17}\mathrm{O}(p,\ensuremath{\gamma})^{18}\mathrm{F}$ reaction rates at lower temperatures that are pertinent to red giants, AGB stars, or massive stars. The present work establishes the $^{17}\mathrm{O}(p,\ensuremath{\gamma})^{18}\mathrm{F}$ reaction rates over a temperature range of $T=\phantom{\rule{0.3em}{0ex}}0.01\text{\ensuremath{-}}1.5\phantom{\rule{0.3em}{0ex}}\mathrm{GK}$ with statistical uncertainties of 10--50%. The new recommended reaction rates deviate from the previously accepted values by an order of magnitude around $T\ensuremath{\approx}0.2\phantom{\rule{0.3em}{0ex}}\mathrm{GK}$ and by factors of 2--3 at $T\phantom{\rule{0.3em}{0ex}}<\phantom{\rule{0.3em}{0ex}}0.1\phantom{\rule{0.3em}{0ex}}\mathrm{GK}$.}, number={5}, journal={Physical Review C}, publisher={American Physical Society (APS)}, author={Fox, C. and Iliadis, C. and Champagne, A. E. and Fitzgerald, R. P. and Longland, R. and Newton, J. and Pollanen, J. and Runkle, R.}, year={2005}, month={May} }