Neutron emission and $\alpha$-particle emission in the ${}_{}{}^{165}{}_{}{}^{}\mathrm{Ho}$ + ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ reaction have been measured for the damped-collision and fusion-fission components of this reaction at a bombarding energy of 8.5 MeV/u. The c.m. neutron energy spectra for damped collisions indicate equal temperatures for the light and heavy fragments, a result consistent with the equilibration of the excitation energy during the interaction time. Pre-equilibrium neutron emission is found to contribute less than 5%. An out-of-plane neutron anisotropy $A_2=0.2\mathrm{}\pm 0.1$ is found. The measured ratios of the neutron multiplicities for the light and heavy fragments suggest a rapid approach of the fragment $\frac{N}{Z}$ ratios during the collision to that corresponding to minimum potential energy of the composite system.

NUCLEAR REACTIONS ${}_{}{}^{165}{}_{}{}^{}\mathrm{Ho}$(${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$, $\mathrm{HI}\mathrm{xn}$)$E_{\mathrm{lab}}=476\mathrm{}$ MeV; measured ${\sigma }_n(E_n,{\theta }_n,{\phi }_n)$; deduced nuclear temperatures, neutron multiplicities, neutron-to-proton ratio $\frac{N}{Z}$, neutron out-of-plane anisotropy $A_2$.

• Received 8 March 1979

DOI:https://doi.org/10.1103/PhysRevC.20.576