Pre-Equilibrium Deexcitation Process for 164Dy(α, xn γ) Reaction and Angular Momentum Transfers

Pre-equilibrium deexcitation process for the 164 Dy(α, x n γ) reaction at E α =90 MeV was studied by means of γ-γ and neutron-γ coincidence method. Properties of the preequilibrium phase were deduced as a function of the neutron multiplicity x . The reaction process was analyzed in terms of the two-phase deexcitation process, the pre-equilibrium phase with the energy parameter (quasi-temperature) of k T p =5 MeV and the equilibrium phase with the temperature of k T e =1.2 MeV. Angular momenta removed by the decaying neutrons at the pre-equilibrium and equilibrium phases, together with the data of the γ-ray multiplicity, account for the angular momenta introduced by the projectile.