Average Energy and Angular Momentum Removed from Dy Compound Nuclei by Neutrons and Photons

Abstract

Excitation functions are presented for many heavy-ion-induced (HI) reactions that produce ${\mathrm{Dy}}^{149}$, ${\mathrm{Dy}}^{150}$, and ${\mathrm{Dy}}^{151}$. Projectiles were ${\mathrm{C}}^{12}$, ${\mathrm{N}}^{14}$, ${\mathrm{N}}^{15}$, ${\mathrm{O}}^{16}$, ${\mathrm{O}}^{18}$, ${\mathrm{F}}^{19}$, ${\mathrm{Ne}}^{20}$, and ${\mathrm{Ne}}^{22}$ of 4 to 10.4 MeV per amu. The reactions studied are all of the type (HI, $\mathrm{xn}$), where $x$ ranges from 3 to 11. A large fraction of the total reaction cross section is accounted for by these (HI, $\mathrm{xn}$) reactions—0.9 at approximately 45 MeV to 0.4 at approximately 120 MeV. An analysis to obtain the energy of the first emitted neutron is presented. Comparison of the results of this analysis to angular-distribution studies suggests that the first neutron removes 2 to $4\hslash$ units of angular momentum. We obtain the relationship between average total photon energy and average angular momentum removed by photons. Comparison with the average individual photon energy from other work leads to an average of $1.8\pm 0.6\hslash$ for the angular momentum removed by each photon. The excitation energy $E_j$ of the lowest lying state of spin $J$ has been estimated.