@misc{angus_frost-schenk_laird_adsley_longland_barton_diget_marshall_chaves_setoodehnia_2024, title={<SUP>21 </SUP>Ne energy levels approaching the α-particle threshold}, volume={109}, ISSN={["2469-9993"]}, url={https://doi.org/10.1103/PhysRevC.109.044323}, DOI={10.1103/PhysRevC.109.044323}, abstractNote={Background: Nuclei around $^{20}\mathrm{Ne}$ exhibit an interplay of different excitations caused by different aspects of nuclear structure, including single-particle and multiparticle configurations and collective rotations. One-nucleon transfer reactions selectively probe single-particle structures in these nuclei. These nuclei are also important to astrophysics, with a number of important reactions proceeding through this mass region.Purpose: Energy levels approaching the $\ensuremath{\alpha}$-particle threshold in $^{21}\mathrm{Ne}$ are of importance to nuclear structure. The $^{20}\mathrm{Ne}(d,p)^{21}\mathrm{Ne}$ reaction was measured and the corresponding spectroscopic nuclear information was extracted.Method: States in $^{21}\mathrm{Ne}$ were populated using the $^{20}\mathrm{Ne}(d,p)^{21}\mathrm{Ne}$ reaction in forward kinematics. Protons were identified in the Triangle Universities Nuclear Laboratory (TUNL) Enge split-pole spectrograph and angular distributions were extracted. Spin-party assignments were made and neutron partial widths were determined based on distorted-wave Born approximation (DWBA) analysis.Results: Several new energy levels were observed at energies of 7176, 7235, 7250, and 7337 keV, and spin-parities are reported which generally agree with previous results where literature was available. Spin and parity assignments are reported for several energy levels along with estimated neutron widths for those states above the neutron threshold (${S}_{n}=6761\phantom{\rule{4pt}{0ex}}\mathrm{keV}$).Conclusions: Results from this study are placed in context with a review of the available literature on all known states in this energy region of $^{21}\mathrm{Ne}$.}, number={4}, journal={PHYSICAL REVIEW C}, author={Angus, C. and Frost-Schenk, J. and Laird, A. M. and Adsley, P. and Longland, R. and Barton, C. J. and Diget, C. Aa. and Marshall, C. and Chaves, F. Portillo and Setoodehnia, K.}, year={2024}, month={Apr} }
 @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{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
               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 17O(α, γ)21Ne and 17O(α, n)20Ne reactions strongly impact weak s-process yields from rotating massive stars at low metallicities. Abundant 16O absorbs neutrons, removing flux from the s-process, and producing 17O. The 17O(α, n)20Ne reaction releases neutrons, allowing continued s-process nucleosynthesis, if the 17O(α, γ)21Ne 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 21Ne states using the 20Ne(d, p)21Ne reaction. Constraints are placed on the ratio of the (α, n)/(α, γ) reaction rates with uncertainties on the rates provided for the first time. The new rates favour the (α, 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{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={AbstractThe rate of the $$^{25}$$25Al(p, $$\gamma $$γ)$$^{26}$$26Si reaction is one of the few key remaining nuclear uncertainties required for predicting the production of the cosmic $$\gamma $$γ-ray emitter $$^{26}$$26Al in explosive burning in novae. This reaction rate is dominated by three key resonances ($$J^{\pi }=0^{+}$$Jπ=0+, $$1^{+}$$1+ and $$3^{+}$$3+) in $$^{26}$$26Si. Only the $$3^{+}$$3+ resonance strength has been directly constrained by experiment. A high resolution measurement of the $$^{25}$$25Mg(d, p) reaction was used to determine spectroscopic factors for analog states in the mirror nucleus, $$^{26}$$26Mg. A first spectroscopic factor value is reported for the $$0^{+}$$0+ state at 6.256 MeV, and a strict upper limit is set on the value for the $$1^{+}$$1+ state at 5.691 MeV, that is incompatible with an earlier ($$^{4}$$4He, $$^{3}$$3He) study. These results are used to estimate proton partial widths, and resonance strengths of analog states in $$^{26}$$26Si contributing to the $$^{25}$$25Al(p, $$\gamma $$γ)$$^{26}$$26Si 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{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{kahl_yamaguchi_kubono_chen_parikh_binh_chen_cherubini_duy_hashimoto_et al._2018, title={First measurement of S-30 + alpha resonant elastic scattering for the S-30(alpha, p) reaction rate}, volume={97}, number={1}, journal={Physical Review C}, author={Kahl, D. and Yamaguchi, H. and Kubono, S. and Chen, A. A. and Parikh, A. and Binh, D. N. and Chen, J. and Cherubini, S. and Duy, N. N. and Hashimoto, T. and et al.}, year={2018} }
 @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} }