Study of the radioactive decays of 140Ba and 140La

Abstract

The intensities of X rays and γ rays from the decays of 140Ba and 140La were measured precisely using Si(Li) and HPGe detectors. The L X-ray intensities in 140Ba decay are reported for the first time. The conversion electrons from these decays are investigated using a mini-orange electron spectrometer. The electron intensities for the (M + N.) conversion of 329, 487, 1596, and 1903 keV transitions in 140Ce were measured for the first time. From the present conversion-electron and γ-ray intensities, the conversion coefficients for various transitions in 140La and 140Ce were determined. Also, the γ–γ directional correlations for 15 cascades in,140Ce were studied using a HPGe–HPGe detector coincidence setup (time resolution = 7 ns). The 109–(329)– 487, 131–242, and 131–266 keV cascades in 140Ce were studied for the first time. The multipole mixing ratios for the 109, 131, 242, 266, 329, 432, 487, 751, 816, 868, 919, 925, and 951 keV transitions in 140Ce are deduced from the present directional correlation and conversion-coefficient measurements.