A R L, Kennington, G, Lotay, D T, Doherty, D, Seweryniak, C, Andreoiu, K, Auranen, M P, Carpenter, W N, Catford, C M, Deibel, K, Hadyńska-Klęk, S, Hallam, D E M, Hoff, T, Huang, R V F, Janssens, S, Jazrawi, J, José, F G, Kondev, T, Lauritsen, J, Li, A M, Rogers, J, Saiz, G, Savard, S, Stolze, G L, Wilson, S, Zhu, Department of Energy (US), Science and Technology Facilities Council (UK), European Commission, Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), and Natural Sciences and Engineering Research Council of Canada
The discovery of presolar grains in primitive meteorites has initiated a new era of research in the study of stellar nucleosynthesis. However, the accurate classification of presolar grains as being of specific stellar origins is particularly challenging. Recently, it has been suggested that sulfur isotopic abundances may hold the key to definitively identifying presolar grains with being of nova origins and, in this regard, the astrophysical 33Cl(p,γ)34Ar reaction is expected to play a decisive role. As such, we have performed a detailed γ-ray spectroscopy study of 34Ar. Excitation energies have been measured with high precision and spin-parity assignments for resonant states, located above the proton threshold in 34Ar, have been made for the first time. Uncertainties in the 33Cl(p,γ) reaction have been dramatically reduced and the results indicate that a newly identified ℓ=0 resonance at Er=396.9(13) keV dominates the entire rate for T=0.25–0.40GK. Furthermore, nova hydrodynamic simulations based on the present work indicate an ejected 32S/33S abundance ratio distinctive from type-II supernovae and potentially compatible with recent measurements of a presolar grain., This work was supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Contract No. DEAC02-06CH11357 and Grants No. DEFG02-94-ER40834, DEFG02-97-ER41041, DEFG02-97-ER41043, DEFG02-94-ER40848, and DESC0014231. UK personnel were supported by the Science and Technologies Facilities Council (STFC) and C. A. was supported by the Natural Sciences and Engineering Research Council of Canada. J. J. acknowledges support by the Spanish MINECO Grant No. AYA2017-86274-P, by the E. U. FEDER funds, and by the AGAUR/Generalitat de Catalunya Grant No. SGR661/2017. This research uses resources of ANL’s ATLAS facility, which is a DOE Office of Science User facility.