Experimental study of two-proton correlated emission fromS29excited states

Abstract

An experiment of a $^{29}\mathrm{S}$ beam bombarding a $^{197}\mathrm{Au}$ target at an energy of 49.2 MeV/u has been performed to study the two-proton correlated emission from $^{29}\mathrm{S}$ excited states. Complete-kinematics measurements were carried out in the experiment. The relative momentum, opening angle, and relative energy of two protons, as well as the invariant mass of the final system, were deduced by relativistic-kinematics reconstruction. The $^{27}\mathrm{Si}$-$p\text{\ensuremath{-}}p$ coincident events were picked out under strict conditions and the phenomenon of $p\text{\ensuremath{-}}p$ correlations was observed among these events. The mechanisms of two-proton emission were analyzed in a simple schematic model, in which the extreme decay modes like $^{2}\mathrm{He}$ cluster emission, three-body phase-space decay, and two-body sequential emission were taken into account. Associated with the Monte Carlo simulations, the present results show that two protons emitted from the excited states between 9.6 MeV and 10.4 MeV exhibit the features of $^{2}\mathrm{He}$ cluster decay with a branching ratio of ${29}_{\ensuremath{-}11}^{+10}%$.