Characterization of nuclear sources via two-neutron intensity interferometry

The neutron energy spectrum and the two-neutron correlation function have b een measured for the E/A = 45 MeV Ni + Al reaction in order to assess the s pace-time characteristics of the neutron emitting source. When comparing th e data to a statistical model, the kinetic energy spectra, the integrated c orrelation function as well as the longitudinal correlation function are re produced by one single source. However, only the inclusion of a short-lived pre-equilibrium component can account for the stronger correlation exhibit ed by neutron pairs emitted with high total momentum. The correlation funct ion from events defined as peripheral by constraints on the highest charge of the projectile-like fragment does show a significantly weaker correlatio n than the minimum bias sample. (C) 1999 Elsevier Science B.V. All rights r eserved.