Inclusive neutron spectra at 0 degrees from the reactions Pb(Ne,n)X and NaF(Ne,n)X at 390 and 790 MeV per nucleon.

Abstract

Inclusive neutron spectra at 0\ifmmode^\circ\else\textdegree\fi{} were measured from both 390- and 790-MeV/u Ne ions on targets of Pb and NaF. A striking peak at a neutron energy slightly below the beam energy per nucleon has a width (in the projectile rest frame) of \ensuremath{\sim}58 MeV/c, which is essentially the same for these two energies and these two targets. We suggest that this narrow peak is projectile evaporation and that it is superimposed on the broader fragmentation process predicted by statistical models. The high-momentum region of the cross section may reflect collective behavior.