Angular Correlations in theC13(He3,pγ)N15Reaction: Levels ofN15

Abstract

The particle-gamma angular-correlation method of Litherland and Ferguson was used to gain information on the decay modes and spin assignments of those ${\mathrm{N}}^{15}$ levels with excitation energies between 8 and 11 MeV. The levels were populated by the ${\mathrm{C}}^{13}({\mathrm{He}}^{3},p){\mathrm{N}}^{15*}$ reaction with a ${\mathrm{He}}^{3}$ energy of 3.0 MeV. Protons were detected in an annular counter at 180\ifmmode^\circ\else\textdegree\fi{} to the beam and gamma rays were detected at several angles between 0\ifmmode^\circ\else\textdegree\fi{} and 90\ifmmode^\circ\else\textdegree\fi{} to the beam. Decay modes are given for 6 levels. Definite spin assignments of $\frac{3}{2}$, $\frac{5}{2}$, $\frac{7}{2}$, $\frac{3}{2}$, and $\frac{3}{2}$ are obtained for the levels at excitation energies of 8.570, 9.762, 9.832, 10.074, and 10.800 MeV, while further restrictions are placed on the spins of some other levels. The present reslts combined with previous work lead to assignments of ${\frac{5}{2}}^{\ensuremath{-}}$ and ${\frac{3}{2}}^{+}$ for the 9.762- and 10.074-MeV levels. Additional information was obtained concerning the dipole-quadrupole or quadrupole-octupole mixing ratios of some of the gamma-ray transitions.