Reaction rate for S31(p,)32Cl and its influence on the SiP cycle in hot stellar hydrogen burning

The excitation energies of the proton unbound states in Cl32 have been measured in the S32(3He,t)32Cl charge exchange reaction with high accuracy. The partial widths of the unbound levels have been calculated to derive the resonance strengths of these states in the S31(p,)32Cl reaction channel. The reaction rate for the S31(p,)32Cl reaction has been calculated and is compared with previous estimates. The role of this reaction for the closure of the SiP cycle is discussed in terms of the temperature and density conditions in hot stellar hydrogen burning

Improvement of the high-accuracy O 17 ( p , α ) N 14 reaction-rate measurement via the Trojan Horse method for application to O 17 nucleosynthesis

The ^{17}\text{O}(p,\ensuremath{\alpha})^{14}\text{N} and ^{17}\text{O}(p,\ensuremath{\gamma})^{18}\text{F} reactions are of paramount importance for the nucleosynthesis in a number of stellar sites, including red giants (RGs), asymptotic giant branch (AGB) stars, massive stars, and classical novae. In particular, they govern the destruction of $^{17}\text{O}$ and the formation of the short-lived radioisotope $^{18}\text{F}$, which is of special interest for \ensuremath{\gamma}-ray astronomy. At temperatures typical of the above-mentioned astrophysical scenario, $T=0.01$--0.1 GK for RG, AGB, and massive stars and $T=0.1$--0.4 GK for a classical nova explosion, the ^{17}\text{O}(p,\ensuremath{\alpha})^{14}\text{N} reaction cross section is dominated by two resonances: one at about ${E}_{R}^{cm}=65$ keV above the $^{18}\text{F}$ proton threshold energy, corresponding to the ${E}_{X}=5.673$ MeV level in $^{18}\text{F}$, and another one at ${E}_{R}^{cm}=183$ keV $({E}_{X}=5.786$ MeV). We report on the indirect study of the ^{17}\text{O}(p,\ensuremath{\alpha})^{14}\text{N} reaction via the Trojan Horse method by applying the approach recently developed for extracting the strength of narrow resonance at ultralow energies. The mean value of the strengths obtained in the two measurements was calculated and compared with the direct data available in literature. This value was used as input parameter for reaction-rate determination and its comparison with the result of the direct measurement is also discussed in the light of the electron screening effect

Proton-halo effects in the 8 B+ 58 Ni reaction near the Coulomb barrier

Elastic scattering of 8B and 7Be on a 58Ni target has been measured at energies near the Coulomb barrier. The total reaction cross sections were deduced from Optical-model fits to the experimental angular distributions. Comparison with other systems shows evidence for protonhalo effects on 8B, as well as for neutron-halo on 6He reactions. While the enhancement in the cross section observed for 8B is explained in terms of projectile breakup, in the case of 6He reactions, the particle transfer proces explains the observed enhancement

Proton-halo effects in the 8 B+ 58 Ni reaction near the Coulomb barrier

Elastic scattering of 8B and 7Be on a 58Ni target has been measured at energies near the Coulomb barrier. The total reaction cross sections were deduced from Optical-model fits to the experimental angular distributions. Comparison with other systems shows evidence for protonhalo effects on 8B, as well as for neutron-halo on 6He reactions. While the enhancement in the cross section observed for 8B is explained in terms of projectile breakup, in the case of 6He reactions, the particle transfer proces explains the observed enhancement