Nuclear structure of30S and its implications for nucleosynthesis in classical novae

Abstract

Background:The uncertainty in the 29 P(p, γ) 30 S reaction rate over 0.1 ≤ T ≤ 1.3 GK was previously determined to span ∼4 orders of magnitude due to the uncertain location of two previously unobserved 3 + and 2 + resonances in the E x = 4.7 -4.8 MeV region in 30 S. Therefore, the abundances of silicon isotopes synthesized in novae, which are relevant for the identification of presolar grains of putative nova origin, were uncertain by a factor of 3.

Multiparticle emission in the decay ofAr31

“…The method is used for the level at 5.2 MeV, which is found to be either a 3 + or 4 + level, with the data favoring the 3 + . In previous studies this level has been suggested to be a 0 + level [12] based on a comparison with the mirror nucleus, or as a 3 + level based on its γ decay [29]. It is currently not known if there might be two levels around this energy, but we can conclude that a 3 + level at 5.227(3) MeV is populated in the decay of 31 Ar.…”

“…This is only possible for the strongest fed level in 30 S at 5.2 MeV. This level has previously been assigned either as 0 + [12] based on levels in the mirror nucleus or as a 3 + state based on its γ decay [29]. To have sufficient statistics all detectors are used with a low-energy cutoff on the first particle of 800 keV and the second of 500 keV, except for the thick detector 5, where 800 keV is used.…”

“…In the last few years the relevant levels in 30 S have been studied intensely [11,12,[29][30][31], such that the energies are now known for the relevant levels, while some disagreements about the spin assignment remain. In this section we present a new method for determining the spin of these levels.…”

“…As demonstrated here, the 2p decay mode can also be used to determine level spins by analyzing proton-proton angular correlations. reference to assignments in the mirror nucleus [12]. A separate analysis of the Gamow-Teller strength using the β3p decay of 31 Ar is in preparation [13].…”

Shell and isospin effects in nuclear charge radii

“…Because of the influence of new magic numbers N = 14, 16, the calculated deformations of these two nuclei are very small with some different mass models such as the Weizsäcker-Skyrme mass model, the finite range droplet model [38], and the HFB calculations [5] adopting three widely used Skyrme forces SLy4, SkP and SkM*. We systematically calculate the difference of the rms charge Due to the perfectly charge-symmetric and charge-independent nuclear force, the deformations and shell correction of a nucleus approximately equal to those of its mirror nucleus [25,40]. Based on the proposed nuclear charge radius formula, one obtains ∆r ch ≈ 3 5 2r s I neglecting the influence of nuclear deformations.…”