The measurement of the L shell particle parameters in the 42 keV E3 transition of Ir 191

Abstract

The 42 keV-129 keV cascade in Ir 191 has been studied with a single-gap electron-gamma angular correlation spectrometer. The ratio of the K conversion electron to L conversion electron intensity of the 129 keV transition is K/ L = 4.42 while the L subshell ratio is (L I+L II/L III = 7.55±0.35 resulting in the magnitude of the mixing amplitude of the 129 keV transition being | δ| 129 = 0.40 or | δ| 129 = 0.395±0.015, respectively. In the 42 keV transition the L subshell ratio is (L I+L II)/L III = 0.97±0.03 indicating the transition to be a pure E3. Directional correlations with the 42 keV L shell electrons and the 129 keV gamma ray were measured and are of the form W( θ) = 1 + A 2 P 2(cos θ). The results with metallic Os sources on different metallic backings are similar. The average values are A 2(42 L II e −−129 γ) = −0.305±0.012 , A 2(42 L III e −−129 γ) = −0.313±0.013 , for the L II and L III e −-γ correlations, respectively. From these correlations and the theoretical form of the particle parameters it is shown that δ 129 is negative. From the e −-γ correlations and the L subshell ratios, the E3 particle parameters that enter the A 2 term for the L II and L III electrons are b 2(42 L II ) = 0.965±0.040 , b 2(42 L III ) = 0.991±0.043 . Numerical theoretical values for L shell particle parameters have not yet been calculated.