P reaction rate*

The ²⁶Si(α, p)²⁹P reaction is considered to have astrophysical importance such as impact on X-ray burst light curves, or on the abundance of ²⁶Al known as a galactic gamma ray source. The cross section of this reaction has, however, never been measured directly, and there was only a study of ³⁰S resonances via limited information from the ²⁸Si(³He, n)³⁰S and ³²S(p, t)³⁰S reactions. We have performed both the ²⁶Si(α, p)²⁹P reaction direct measurement and the ²⁶Si(α, α)²⁶Si resonant scattering measurement in inverse kinematics to determine the reaction cross section at higher energies and to obtain alpha resonance information in the ³⁰S compound system, respectively. The experiment employed the thick-gas-target inverse-kinematics method with a ²⁶Si radioactive isotope (RI) produced at the Center-for-the-Nuclear-Study RI Beam Separator (CRIB) of the University of Tokyo. In the presentation, we will discuss the α resonant scattering result, which covers the excitation energy range of E_x = 12–16 MeV and was analyzed by R-matrix fit, to update the ²⁶Si(α, p)²⁹P thermal reaction rate.