Toward concordance of $E_{x}$ and $J^{\pi}$ values for proton unbound 31S states

Abstract

Abstract. Nucleosynthesis in classical novae on oxygen-neon white dwarfs is sensitive to the poorly constrained thermonuclear rate of the 30 P(p,γ) 31 S reaction. In order to improve this situation, a variety of experiments have been performed over the past decade to determine the properties of proton unbound 31 S levels up to an excitation energy of ≈ 6.7 MeV. Inconsistencies in the energies and J π values for these levels have made it difficult to produce a useful 30 P(p,γ) 31 S reaction rate based on experimental information. In the present work, we revisit a subset of published data on the structure of 31 S in order to shed light on these problems. First, we present an alternative calibration of 31 P( 3 He,t) 31 S spectra using newly available high precision data in order to address discrepant 31 S excitation energies. Second, we apply a similar method to a recently acquired 32 S(d,t) 31 S spectrum. Third, for a different 31 P( 3 He,t) 31 S experiment in which angular distributions were acquired, we present alternative fits to the experimental data in order to address discrepant 31 S J π values. Finally, we compare the J π values from 31 P( 3 He,t) 31 S to those reported from in beam γ ray spectroscopy experiments in order to search for potential resolutions to the inconsistencies. Overall, viable new solutions to some of the problems emerge, but other problems persist.PACS. 26.50.+x Nuclear physics aspects of novae, supernovae, and other explosive environments -27.30.+t Properties of nuclei listed by mass ranges: 20 ≤ A ≤ 38

First measurement of the S34(p,γ)Cl35 reaction rate through indirect methods for presolar nova grains

“…To these we can add the δ 34 S/ 32 S ratio predicted by the nova model adopted in the present work, −696−−643. We note that nova model predictions for Si isotopes are not well constrained due to uncertainties in the 30 P(p,γ ) 31 S reaction rate [38,39] and that the prediction for the 33 S/ 32 S ratio arises from a limited study using a nova model with a single set of initial conditions [12] (as in the present study). Nonetheless the above constraints can serve as guides for diagnostic isotopic signatures of nova grains.…”

Detailed study of the decay Cl31(βγ)S31

“…A detailed overview of the history of 30 P(p, γ) 31 S studies which have been used to piece together the current understanding of the 31 S resonances in the energy region of interest [9][10][11][12][13][14][15][16][17][18][19][20][21] up to 2014 is given in Ref. [22], and several recent studies have been published as well [23][24][25]. The reader is referred to these works for a full history; here we will briefly discuss selected experiments which are most relevant to the present work.…”

Constraining the P30(p, γ)<

“…Over the past two decades, significant theoretical [20] and experimental effort has been devoted to studying the level structure of 31 S in an effort to determine resonance properties. Single-nucleon transfer reactions [21][22][23][24][25][26][27][28], in-beam γ-ray spectroscopy [29][30][31][32][33][34][35], β-decay measurements [36][37][38][39], and the chargeexchange reaction 31 Pð 3 He; tÞ 31 S [23,40,41] have all been employed to constrain the spins, parities, and decay widths of 31 S excited states. It is likely that all of the potentially important resonances contributing to 30 Pðp; γÞ 31 S in novae have been observed using various nuclear spectroscopy techniques [42].…”