Multifragmentation induced by relativistic α projectiles

Multifragmentation of the system α${+}^{197}$Au has been studied at incident energies of 1 and 3.6 GeV/nucleon with the new 4π setup, FASA. Mass, energy, and velocity of a few fragments are measured with high precision using time-of-flight telescopes, while for the other fragments, global multiplicity information is obtained from 55 CsI(Tl) detectors covering the main part of 4π. Very high mean IMF (intermediate mass fragment) multiplicities of 〈M${\mathrm{〉}}_{\mathrm{IMF}}$=5.1±0.8 are observed at the higher incident energy. Compared to the lower incident energy, they increase by 40%, indicating an increasing energy deposition with increasing incident energy.