Neutron removal in peripheral relativistic heavy-ion collisions

We investigate the relativistic Coulomb fragmentation of $^{197}\mathrm{Au}$ by heavy ions, leading to one-, two-, and three-neutron removal. To resolve the ambiguity connected with the choice of a specific minimum impact parameter in a semiclassical calculation, a microscopic approach is developed based on nucleon-nucleon collisions (``soft-spheres'' model). This approach is compared with experimental data for $^{197}\mathrm{Au}$ at 1 GeV/nucleon and with a calculation using the ``sharp-cutoff'' approximation. We find that the harmonic-oscillator model predicting a Poisson distribution of the excitation probabilities of multiphonon states gives a good agreement with one-neutron removal cro…