Half-lives of several states in neutron-rich nuclei from spontaneous fission of ${}^{252}\mathrm{Cf}$

Half-lives $\left(T_{1∕2}\right)$ of several states which decay by delayed $\gamma$ transitions were determined from time-gated triple $\gamma$ coincidence method. We determined, for the first time, the half-life of $330.6+x$ state in ${}^{108}\mathrm{Tc}$ and the half-life of $19∕2^{-}$ state in ${}^{133}\mathrm{Te}$ based on the new level schemes. Three half-lives of ${}^{99}\mathrm{Zr}$, ${}^{134}\mathrm{Te}$, and ${}^{137}\mathrm{Xe}$ are consistent with the previously reported ones. These results indicate that this new method is useful for measuring the half-lives.

Figure 1

Partial level schemes of ${}^{137}\mathrm{Xe}$ [9, 10], ${}^{133}\mathrm{Te}$ [3, 4], and ${}^{134}\mathrm{Te}$ [11, 12]. $♯$ denotes the double gated transitions to extract the half-life. Average half-life of $102\left(15\right)\text{ns}$ is shown for ${}^{133}\mathrm{Te}$. Relative intensities of gamma rays are given in parentheses.

Figure 2

Coincidence spectra with double gates set on 721.1- and $933.4\text{−}\text{keV}$ transitions in ${}^{133}\mathrm{Te}$ with coincidence time windows $\left(t_w\right)$ of 48, 100, 300, and $500\text{ns}$. See figures of Ref. 2 for ${}^{95,97}\mathrm{Sr}$.

Figure 3

(Color online) $N\left(1150.6\right)∕N\left(738.6\right)$ vs coincidence time window $\left(t_w\right)$ plot for ${}^{133}\mathrm{Te}$. The fitted half-life $\left(T_{1∕2}\right)$ value (solid curve) is $97\left(7\right)\text{ns}$. See figures of Ref. 2 for ${}^{95,97}\mathrm{Sr}$.

Figure 4

Partial level schemes of ${}^{95}\mathrm{Sr}$ [2, 16], ${}^{97}\mathrm{Sr}$ [2, 17], ${}^{99}\mathrm{Zr}$ [18, 19], and ${}^{108}\mathrm{Tc}$ [5]. “♯” denotes the double gated transitions to extract the half-life.