Indirect study of low-energy resonances inP31(p,α)28

Abstract

The reaction sequences governing the reaction How in the rp process are important for the understanding of the energy generation and nucleosynthesis of heavy elements in hot and explosive stellar hydrogen burning. Of considerable interest are (p, n) reactions along the process path which lead to the formation of reaction cycles rather than to chains of proton capture processes and P decays. Previous direct attempts to measure the low-energy reaction cross sections for 'P(p, n) Si and Cl(p, a) S resulted only in upper limits for the strengths of possible low-energy resonances which may dominate the reaction rates. In this paper an indirect experimental approach is presented to study the structure of the low-energy unbound states in the compound nuclei S and Ar. The results allow a more accurate determination of the contributions of these low-energy levels in the (p, n) reaction channel.PACS number(s): 25.40.Ny, 25.40.Hs, 27.30.+t, 97.10.Cv

Proton‐induced Thermonuclear Reaction Rates for A = 20–40 Nuclei

“…The contributions of E R cm º 372 four natural parity states close to the proton threshold were taken into account. The corresponding resonance strengths have been estimated from measurements of (Endt 1998), and (Ross et al 1995), and The latter values were uc pc ! a /!…”

“…Two states near the proton threshold have been taken into account but only their total contribution is listed in Table 10. The total uc value of the doublet is estimated by using the spectroscopic factor reported in the 31P(3He, d)32S stripping work of Kalifa et al (1978) and the measured value of (Ross et al 1995). Note !…”

“…Only the ( p, a) resonance strengths corresponding to the levels at and 8672 keV are given in Table 10. The strengths have been estimated from the E x \ 8556 proton partial widths, together with the measured upper limits for (Ross et al 1995). The proton bombarding energy !…”

“…z See discussion in text. aa Estimated by using from Ross et al 1995 ; the measured upper limits of (Ross et al 1995) for and ! c /!…”

“…The resonance strengths for the threshold states have been estimated with ! p and the measured values of (Ross et al 1995). The direct capture S-factor was adopted from Iliadis et al (1994).…”