Gamma-Gamma Directional Correlations inCo59,Xe131, andHg198

Abstract

The directional correlations of low intensity gamma-gamma cascades have been measured using NaI scintillation counters in a coincidence arrangement of 1.5×${10}^{-8\mathrm{}}$ second resolving time. The correlation in the 3 percent intensity 191-1089-kev cascade in ${\mathrm{Co}}^{59}$ is compatible with a $\frac{3}{2}-\frac{5}{2}-\frac{7}{2}$ spin assignment. The coincidences from the 284-80-kev cascade in ${\mathrm{Xe}}^{131}$ are isotropic within an error of 2 percent, supporting the assignment of spin ½ to the 80-kev level. The large correlation observed in the ∼1 percent intensity 680-411-kev cascade of ${\mathrm{Hg}}^{198}$ characterizes the spins of the levels involved as 2, 2, 0 and the 680-kev transition as a mixture of 60 percent $E2\mathrm{}$ and 40 percent $M1\mathrm{}$.