Electron Scattering in theK-Electron—Gamma Angular Correlation inSn117

From directional correlation measurements using sources of various thicknesses, the angular correlation coefficient, $b_2{A}_2$, for the $K$-electron—gamma cascade in ${\mathrm{Sn}}^{117}$ is found to be -0.143±0.011. This requires a mixture of (${0.15}_{-0.10\mathrm{}}^{+0.15\mathrm{}}$) percent $E2\mathrm{}$ in the predominantly $M1\mathrm{}$ $\frac{3}{2}\to \frac{1}{2}$ transition. The sign of the mixture ratio is positive. The theory describing the reduction of the angular correlation coefficient as the result of multiple elastic scattering in the source is shown to be valid for rather thick sources where even inelastic scattering is appreciable.