Evidence for shape deformations of fragments in deep inelastic collisions

Abstract

The number and energy spectra of neutrons evaporated by the heavy and light fragments in deep inelastic collisions have been obtained for the system 240 MeV40Ar +197Au. They indicate that at the scission point the deformation energy is a large part of the total excitation energy espe cially for the light fragment. In the last two years, neutron emission has been studied in deep inelastic reactions1−6. All the results are similar: the incident energy which is lost during the process is transformed into excitation energy of the final fragments and is shared between the two products proportionnally to their masses. This means that the nuclear temperature was uniform in the composite system. The excitation energy equilibration time is really very short since equilibration is achieved after reaction times as small as 10−22 s2,6. Moreover, no preequilibrium emission (direct neutrons-) has been observed.