The He-3+He-5 -> alpha plus alpha reaction below the Coulomb barrier via the Trojan Horse Method

For the first time in an application to nuclear astrophysics, a process induced by the unstable He-5 = (He-4-n) nucleus, the He-3+He-5 -> 2 alpha reaction, has been studied through the Trojan Horse Method (THM). For that purpose, the quasi-free (QF) contribution of the Be-9(He-3,alpha alpha)He-4 reaction was selected at E3He = 4 MeV incident energy. The reaction was studied in a kinematically complete experiment following a recent publication (Spitaleri et al. in Eur Phys J A 56:18, 2020), where for the quasi free contribution the momentum distribution between alpha and He-5 particle cluster in the Be-9 nucleus in the ground state have been extracted. The angular distribution of the QF He-3+He-5 -> 2 alpha reaction was measured at theta(cm) = 78 degrees-115 degrees. The energy dependence of the differential cross section of the He-3+He-5 -> 2 alpha virtual reaction was extracted in the energy range E-cm = 0-650 keV. The total cross section obtained from the Trojan-horse methodwas normalized to absolute cross sections from a theoretical calculation in the energy range E-cm =300-620 keV.