Experimental investigation of the³⁰S(α, p) thermonuclear reaction in x-ray bursts

Abstract

Abstract. We performed the first measurement of 30 S+α resonant elastic scattering to experimentally examine the 30 S(α, p) stellar reaction rate in type I x-ray bursts. These bursts are the most frequent thermonuclear explosions in the galaxy, resulting from thermonuclear runaway on the surface of accreting neutron star binaries. The 30 S(α, p) reaction plays a critical role in burst models, yet very little is known about the compound nucleus 34 Ar at these energies nor the reaction rate itself. We performed a measurement of alpha elastic scattering with a radioactive beam of 30 S to experimentally probe the entrance channel. Utilizing a gaseous active target system and silicon detector array, we extracted the excitation function from 1.8 to 5.5 MeV near 160 • in the center-of-mass frame. The experimental data were analyzed with an R-Matrix calculation, and we discovered several new resonances and extracted their quantum properties (resonance energy, width, spin, and parity). Finally, we calculated the narrow resonant thermonuclear reaction rate of 30 S(α, p) for these new resonances.