Evaporation recoil effects: Asymmetries in neutron, projectile-fragment coincidences for 35 MeV/nucleon 14N

Abstract

Simulations of neutron evaporation from light heavy ions are presented to illustrate experimental biases present in coincidence experiments. In particular, the case presented involves neutrons observed in coincidence with quasi-elastic boron fragments from collisions of $^{14}\mathrm{N}$ with $^{165}\mathrm{Ho}$ at a bombarding energy of 35 MeV/nucleon. The left-right asymmetry observed experimentally in the high energy neutron spectra at angles of \ifmmode\pm\else\textpm\fi{}60\ifmmode^\circ\else\textdegree\fi{} and \ifmmode\pm\else\textpm\fi{}90\ifmmode^\circ\else\textdegree\fi{} cannot be reproduced together with the correct angular distribution if only a projectile-like source is assumed to create the observed spectra, and this suggests that some other process is required to explain the data. Some general features of the simulations will be compared with results of moving-source analyses.