Multifragmentation induced by relativistic α projectiles

Hot nuclei which decay by multifragmentation can be produced either with heavy projectiles at intermediate energies or with very light projectiles at relativistic energies. The authors have studied the reaction α + Au at 1 and 3.65 GeV/nucleon at the synchrophasotron in Dubna using the new 4π setup FASA (S.P Avdeyev et al., NIM A (in print)), since all fragments originate from the target and compression should be negligible. By triggering on one IMF very high IMF multiplicities are observed corresponding to primary IMF multiplicities of 3.6 and 5.3 at 1 and 3.65 GeV/nucleon, respectively. This 50% increase demonstrates the still increasing energy deposit at these high incident energies. The relative velocities of IMF-IMF coincidences at large relative angles decrease both with incident energy and with increasing IMF multiplicity. This decrease of the mutual Coulomb repulsion could be interpreted as an increasing breakup volume of the decaying system. Together with the observed suppression of IMF-IMF coincidences at small correlation angles, the data support the scenario of a simultaneous breakup of a very dilute system