The ¹²C(p, p′3α) breakup reaction induced by 14, 18 and 26 MeV protons

Double-differential cross sections (DDXs) of emitted protons and αs particles were measured for proton-induced reactions on ¹²C at 14, 18 and 26MeV in order to investigate the ¹²C(p, p′3α) breakup reaction. The experimental DDXs were analyzed on the assumption that the (p, p′3α) reaction proceeds through two major processes, a three-body simultaneous breakup (3BSB) process (i.e., p+¹²C→p+α+⁸Be*_2094Mev) and sequential decay processes from unstable nuclei produced by (p, p′) and (p, α) reactions (i.e., ¹²C, ⁹B, ⁸Be and ⁵Li). Partial cross sections for the various reaction channels were extracted from the measured DDXs by a least squares method with two fitting functions: a three-body phase distribution function for the 3BSB process and a Breit-Wigner function for the transition to a discrete level in the first step of the sequential decay process. The result showed that the ¹²C(p, p′3α) reaction took place predominantly via nearly isotropic particle emission in the 3BSB process, and emission of protons and α particles with low energies was explained well by the sequential decay via ¹²C* and ⁹B_g.s Experimental (p, p) and (p, p′) scattering cross sections at 26 MeV were reproduced well by the coupled-channels calculation with the soft-rotator model. The experimental DDXs were compared with a Monte Carlo calculation based on the SCINFUL/DDX code and the latest intermediate energy nuclear data evaluation library LA150.