Disintegration ofLa135and Confirmatory Experiments onNd147

Abstract

The disintegrations of ${\mathrm{La}}^{135}$, ${\mathrm{Ba}}^{135m}$, and ${\mathrm{Nd}}^{147}$ have been studied with the help of magnetic spectrometers and scintillation counters. ${\mathrm{La}}^{135}$ decays almost entirely by electron capture. The half-life has been found to be 19.8±0.2 hr. Electron capture to the ground state takes place in 95-97% of all disintegrations. Gamma-rays of energies 104, 218, 265, 295, 367, 481, 588, 642, 862 kev have been found. There is a very weak positron spectrum. The internal-conversion coefficient of the line at 481 kev has been measured. The value ${\alpha }_K=0.0130\mathrm{}$ indicates an $M1\mathrm{}$ transition. The line at 862 kev has ${\alpha }_K=2.5\mathrm{}\times {10}^{-3\mathrm{}}$. The disintegration scheme is discussed. The internal-conversion coefficient of the line at 265 kev from ${\mathrm{Ba}}^{135m}$ has been found to be ${\alpha }_K=3.82\mathrm{}\pm 0.2$. The spectrum of ${\mathrm{Nd}}^{147}$ has been reinvestigated, confirming the scheme of Hans, Saraf, and Mandeville. The internal-conversion coefficient for the line at 92 kev has been found to be 1.52±0.05.