Four α correlations in nuclear fragmentation: a game of resonances * *Supported by the National Natural Science Foundation of China (11765014, 11865010, 11905120, 11605097, U2032146, 11421505), the Robert A.Welch Foundation (A-1266), the US Department of Energy (DE-FG02-93ER40773), Natural Science Foundation of Inner Mongolia (2018MS01009, 2019JQ01), the Chinese Academy of Sciences (CAS) President's International Fellowship Initiative (2015VWA070), the Strategic Priority Research

Abstract

Heavy ion collisions near the Fermi energy produce a ‘freezout’ region where fragments appear and later decay, emitting mainly neutrons, protons, alpha particles, and gamma rays. These decay products carry information about the decaying nuclei. Fragmentation events may result in high yields of boson particles, especially alpha particles, and may carry important information about the nuclear Bose Einstein condensate (BEC). We study ‘in medium’ four α correlations and link them to the ‘fission’ of 16O in two 8Be in the ground state or 12C*(Hoyle state)+α. Using novel techniques for the correlation functions, we confirm the resonance of 16O at 15.2 MeV excitation energy, and the possibility of a lower resonance, close to 14.72 MeV. The latter resonance is the result of all α particles having 92 keV relative kinetic energies.