Constraining the P30(p, γ)<

Abstract

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Proton capture on $^{30}$P in novae: On the existence of states at $6.40$ MeV and $6.65$ MeV in $^{31}$S

“…Calculated 30 P(p, γ) reaction rates for the two resonances discussed in this work, at Er = 270 keV and Er = 517 keV. For comparison we also show the contribution of the important 259 keV resonance reported in Refs [8,9]…”

“…This 6390 keV state (at E r = 259 keV) is arguably the most important 30 P(p, γ) resonance [9] known at the present time, with a calculated resonance strength of 24 µeV [9]. Very recently a revised ωγ = 80 (48) µeV [8] was reported for this Although the ωγ for this resonance is reported with 60% relative uncertainty [8], we evaluate the rate based on its central value. We forgo uncertainty bands in this plot because of the reasons specified in Ref.…”

“…This reaction rate significantly impacts nucleosynthesis in the Si-Ca mass region [1] and has a large uncertainty, mainly because of the present unavailability of intense 30 P beams for both direct and indirect measurements. Nevertheless, despite this limitation, there has been considerable progress in constraining the 30 P(p, γ) 31 S reaction rate using indirect probes [8][9][10][11][12][13][14][15][16][17][18][19][20][21].…”

“…Resonances in the 30 P(p, γ) reaction compete with 30 P β + decay (t 1/2 ≈ 2.5 min) at peak nova temperatures of around 0.1-0.4 GK, thereby controlling the nucleosynthesis path towards heavier species [1]. The dominant resonances are expected to be in the range of ∼ 600 keV [22] above the 6131 keV proton emission threshold in 31 S. This corresponds to an excitation region 6.1 E x 6.7 MeV in 31 S. Consequently, there have been several experimental investigations [8][9][10][11][12][13][14][15][16][17][18][19][20][21] of 31 S excited states in this energy range, to indirectly determine 30 P(p, γ) resonance strengths to these states. Available spectroscopic information from these experiments have led to a debate about the existence of a possible state at 6.4 MeV, which may significantly contribute to the total 30 P(p, γ) reaction rate.…”