Decay ofY95

Abstract

The decay of ${\mathrm{Y}}^{95}$ has been investigated with semiconductor and scientillation spectrometers. The half-life of this isotope was measured to be 10.7±0.2 min. Its total disintegration energy is 4.43±0.02 MeV. The beta decay to the ground state of ${\mathrm{Zr}}^{95}$ (82% of the total decay) is expected to be unique first-forbidden. However, the $log{f}_{1}t$ value of 7.45 is very low for this type of beta transition. Furthermore, the typical unique-first-forbidden shape has not been confirmed. The other $\beta$-ray branches excite a complex system of more than 20 levels in ${\mathrm{Zr}}^{95}$, with $\gamma$-ray energies up to 4 MeV. The lower levels of this scheme agree with those observed by Cohen and Chubinsky with the ${\mathrm{Zr}}^{94}(d, p)$ reaction. Using their spin assignments for the lower levels, it was possible to suggest spins and parities of some higher energy levels from the present work. Appendices are included with some new remarks on the decay of ${\mathrm{Y}}^{94}$, a source contaminant, and on the decay of ${\mathrm{Cl}}^{38}$, an isotope used for calibration purposes.