Electron spectral shape of the third-forbidden ${\hat{I}}^2$-decay of ${}^{87}$Rb measured using a Rb${}_2$ZrCl${}_6$ crystal scintillator

P. Belli, R. Bernabei, F. Cappella +12

In recent years, interest in experimental studies of ${\hat{I}}^2$-decay electron spectra -- often referred to as ${\hat{I}}^2$ spectra -- has been growing. This is particularly true for ${\hat{I}}^2$ transi…