Space-time evolution of the reactions N14+27Al, Au197 at E/A=75 MeV and Xe129+27Al, Sn122 at E/A=31 MeV probed by two-proton intensity interferometry
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abstract
Two-proton correlation functions have been measured at lab25for the forward kinematics reactions N14+27Al, N14+197Au at E/A=75 MeV, for the inverse kinematics reaction Xe129+27Al at E/A=31 MeV, and for the nearly symmetric reaction Xe129+122Sn at E/A=31 MeV. For the reactions at 75 MeV per nucleon, the correlation functions exhibit pronounced maxima at relative proton momenta, q20 MeV/c, and minima at q0 MeV/c. These correlations indicate emission from fast, nonequilibrium processes. They are analyzed in terms of standard Gaussian source parametrizations and compared to microscopic simulations performed with the Boltzmann-Uehling-Uhlenbeck equation. For the reactions at 31 MeV per nucleon, the two-proton correlation functions do not exhibit maxima at q20 MeV/c, but only minima at q0 MeV/c. These correlations indicate emission on a slower time scale. They can be reproduced by calculations based on the Weisskopf formula for evaporative emission from fully equilibrated compound nuclei. For all reactions, the measured longitudinal and transverse correlation functions are very similar, in agreement with theoretical predictions. 1991 The American Physical Society.
