@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 $^{18}\mathrm{F}(p,\ensuremath{\alpha})^{15}\mathrm{O}$ reaction is key to determining the $^{18}\mathrm{F}$ 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 subthreshold states in $^{19}\mathrm{Ne}$ that reduces these uncertainties. The $^{20}\mathrm{Ne}(^{3}\mathrm{He},^{4}\mathrm{He})^{19}\mathrm{Ne}$ neutron pick-up reaction was used to populate $^{19}\mathrm{Ne}$ excited states, focusing on the energy region of astrophysical interest $(\ensuremath{\approx}6--7 \mathrm{MeV})$. 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 $({E}_{r}^{\text{c.m.}}=\ensuremath{-}277 \mathrm{keV})$ was found to have spin and parity of $3/{2}^{+}$ and we confirm the existence of an unresolved doublet close to 6.288 MeV $({E}_{r}^{\text{c.m.}}=\ensuremath{-}120 \mathrm{keV})$ with ${J}^{\ensuremath{\pi}}=1/{2}^{+}$ 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 $^{7}\mathrm{Be}(\ensuremath{\alpha},\ensuremath{\gamma})^{11}\mathrm{C}$ reaction with unknown strengths using an intense radioactive $^{7}\mathrm{Be}$ beam and the DRAGON recoil separator. We report on the first measurement of the 1155 and 1110 keV resonance strengths of $1.73\ifmmode\pm\else\textpm\fi{}0.25(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.40(\mathrm{syst})\text{ }\text{ }\mathrm{eV}$ and ${125}_{\ensuremath{-}25}^{+27}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}15(\mathrm{syst})\text{ }\text{ }\mathrm{meV}$, respectively. The present results have reduced the uncertainty in the $^{7}\mathrm{Be}(\ensuremath{\alpha},\ensuremath{\gamma})^{11}\mathrm{C}$ reaction rate to $\ensuremath{\sim}9.4%--10.7%$ over $T=1.5--3\text{ }\text{ }\mathrm{GK}$, which is relevant for nucleosynthesis in the neutrino-driven outflows of core-collapse supernovae ($\ensuremath{\nu}p$ process). We find no effect of the new, constrained reaction rate on $\ensuremath{\nu}p$-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={Massive stars are crucial to galactic chemical evolution for elements heavier than iron. Their contribution at early times in the evolution of the Universe, however, is unclear due to poorly constrained nuclear reaction rates. The competing $^{17}$O($\alpha,\gamma$)$^{21}$Ne and $^{17}$O($\alpha,n$)$^{20}$Ne reactions strongly impact weak s-process yields from rotating massive stars at low metallicities. Abundant $^{16}$O absorbs neutrons, removing flux from the s-process, and producing $^{17}$O. The $^{17}$O($\alpha,n$)$^{20}$Ne reaction releases neutrons, allowing continued s-process nucleosynthesis, if the $^{17}$O($\alpha,\gamma$)$^{21}$Ne reaction is sufficiently weak. While published rates are available, they are based on limited indirect experimental data for the relevant temperatures and, more importantly, no uncertainties are provided. The available nuclear physics has been evaluated, and combined with data from a new study of astrophysically relevant $^{21}$Ne states using the $^{20}$Ne($d,p$)$^{21}$Ne reaction. Constraints are placed on the ratio of the ($\alpha,n$)/($\alpha,\gamma$) reaction rates with uncertainties on the rates provided for the first time. The new rates favour the ($\alpha,n$) reaction and suggest that the weak s-process in rotating low-metallicity stars is likely to continue up to barium and, within the computed uncertainties, even to lead.}, 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 The production of the p–nuclei is one of the unsolved puzzles in nuclear astrophysics. A possible mechanism is the nucleosynthesis in the neutrino–driven winds of core–collapse supernovae (νp–process), but it carries uncertainties, mostly in the supernova dynamics and the nuclear physics input. The pp-chain breakout reaction 7 Be( α,γ ) 11 C, which occurs prior to the supernova explosion, was identified as an important link which can influence the nuclear flow of the z/p-process and the final abundances of the p-nuclei. Nevertheless, its reaction rate is poorly known over the relevant energy range (T=1.5-3 GK). To improve the 7 Be( α,γ ) 11 C rate for vp- process nucleosynthesis temperatures, the first measurement of the strengths of two important resonances with unknown strength was recently performed at TRIUMF. A radioactive 7 Be beam ( t1/2 = 53.24 d) beam and the DRAGON recoil separator were used. The experimental details and preliminary results for the resonance strengths will be discussed.}, 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={The rate of the $^{25}$Al($p$,$\gamma$)$^{26}$Si reaction is one of the few key remaining nuclear uncertainties required for predicting the production of the cosmic $\gamma$-ray emitter $^{26}$Al in explosive burning in novae. This reaction rate is dominated by three key resonances ($J^{\pi}=0^{+}$, $1^{+}$ and $3^{+}$) in $^{26}$Si. Only the $3^{+}$ resonance strength has been directly constrained by experiment. A high resolution measurement of the $^{25}$Mg($d$,$p$) reaction was used to determine spectroscopic factors for analog states in the mirror nucleus, $^{26}$Mg. A first spectroscopic factor value is reported for the $0^{+}$ state at 6.256 MeV, and a strict upper limit is set on the value for the $1^{+}$ state at 5.691 MeV, that is incompatible with an earlier ($^{4}$He,$^{3}$He) study. These results are used to estimate proton partial widths, and resonance strengths of analog states in $^{26}$Si contributing to the $^{25}$Al($p$,$\gamma$)$^{26}$Si reaction rate in nova burning conditions.}, 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 $^{38}\mathrm{K}(p,\ensuremath{\gamma})\phantom{\rule{0.16em}{0ex}}^{39}\mathrm{Ca}$ reaction rate over the nova temperature regime ($\ensuremath{\sim}0.1--0.4$ GK), and thus the nuclear structure of $^{39}\mathrm{Ca}$ 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 $^{38}\mathrm{K}+p$ system, and to improve the uncertainties in energies of the known astrophysically significant proton resonances in $^{39}\mathrm{Ca}$.Methods: The level structure of $^{39}\mathrm{Ca}$ was investigated via high-resolution charged-particle spectroscopy with an Enge split-pole spectrograph using the $^{40}\mathrm{Ca}(^{3}\mathrm{He},\ensuremath{\alpha})\phantom{\rule{0.16em}{0ex}}^{39}\mathrm{Ca}$ reaction. Differential cross sections were measured over six 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 $^{38}\mathrm{K}(p,\ensuremath{\gamma})\phantom{\rule{0.16em}{0ex}}^{39}\mathrm{Ca}$ 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 $^{38}\mathrm{K}(p,\ensuremath{\gamma})\phantom{\rule{0.16em}{0ex}}^{39}\mathrm{Ca}$ upper limit thermonuclear reaction rate at 0.1--0.4 GK is higher than that determined by Christian et al. [Phys. Rev. C 97, 025802 (2018)] 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 anti-correlation 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 anti-correlation, the nuclear reactions involved must be well understood. The $^{39}$K+p reactions are one such pair of reactions. Here, we report a new evaluation of the $^{39}$K(p,$\gamma$)$^{40}$Ca reaction rate by taking into account ambiguities and measurement uncertainties in the nuclear data. The uncertainty in the $^{39}$K(p,$\gamma$)$^{40}$Ca reaction rate is larger than previously assumed, and its influence on nucleosynthesis models is demonstrated. We find the $^{39}$K(p,$\gamma$)$^{40}$Ca reaction cross section should be the focus of future experimental study to help constrain models aimed at explaining the magnesium-potassium anti-correlation 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} }