Hard Gammas from Low-Energy Heavy-Ion Collisions

Single-particle radiative mechanism of $\gamma$ emission embedded into the pre-equilibrium exciton model is used to calculate the $\gamma$ emission from a decay of $^{160}$Er$^{*}$ created in two different ways. The initial stage of a reaction is described using momentum-space overlaps of colliding nuclei. We can reproduce the main features of the observed $\gamma$ energy spectra including the fact that the spectrum observed in more symmetric combination is slightly harder than in the other case.