Enhanced α α-particle production from fusion evaporation reactions leading to 46Ti

Abstract

In this paper, we report a detailed study of the deexcitation of the ⁴⁶Ti compound nucleus populated by means of four different reactions: ¹⁶O+³⁰Si at 7 and 8 AMeV, ¹⁸O+²⁸Si at 7 AMeV and ¹⁹F+²⁷Al at 7 AMeV. The emitted light charged particles and the heavy fragments were measured with the GARFIELD high granularity 4π detection array. Complete events are chosen through total charge (Z_TOT=22) detection and full momentum transfer. Moreover, the fusion-evaporation events were selected by the condition that only one heavy fragments was detected in coincidence with the light charged particles. The analysis of global observables, such as charge distribution and light charged particle multiplicities, is compatible with the formation of a thermalized compound nucleus for all the four reactions. Nevertheless, an enhanced emission of α-particles with respect to a pure statistical picture is present at very forward angles (o). This enhancement is mainly observed in the even Z residue exit channels populated through the emission of only α-particles.