STUDY OF A FAST COLLECTIVE MODE IN DEEP INELASTIC REACTIONS - QUANTAL FLUCTUATIONS

We have measured for the 430 MeV86Kr+92.98Mo systems the triple differential cross section d3σ/dEdAdZ (E=kinetic energy, A=mass and Z=atomic number) of the reaction products in the angular range (θ=25, 45°). We focussed attention on a fast collective mode in deep inelastic reactions: the neutron excess or charge equilibration. This mode is shown to relax very quickly to equilibrium within a time scale of the order of 10-22s. It is shown that this collective degree of freedom exhibit a quantal behavior which can be seen in the observation of quantal fluctuations. The experimental results are discussed in terms of a simple equilibrium model. The giant dipole resonance of the composite system could be closely connected to this neutron excess mode. © 1979 Springer-Verlag.