@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{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{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{psaltis_chen_kroll_liang_connolly_davids_hutcheon_lennarz_ruiz_williams_et al._2020, title={Study of the Be-7(alpha, gamma)C-11 reaction with DRAGON for nu p-process nucleosynthesis}, volume={1668}, ISSN={["1742-6596"]}, DOI={10.1088/1742-6596/1668/1/012035}, abstractNote={Abstract}, journal={NUCLEAR PHYSICS IN ASTROPHYSICS IX (NPA-IX)}, author={Psaltis, Athanasios and Chen, A. A. and Kroll, L. and Liang, J. and Connolly, D. S. and Davids, B. and Hutcheon, D. A. and Lennarz, A. and Ruiz, C. and Williams, M. and et al.}, 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{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{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{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} }