Lifetime measurement of the first excited state in ${}^{37}\mathrm{S}$

Lifetime of the $3/2^{-}$ first excited state in ${}^{37}\mathrm{S}$ populated by the ${\beta }^{-}$ decay of ${}^{37}\mathrm{P}$ has been measured using $\beta -\gamma$ delayed coincidence technique. The $B(E2;7/2^{-}\to 3/2^{-})$ value in ${}^{37}\mathrm{S}$ deduced from the lifetime comes close to the $B(E2;0^{+}\to 2_1^{+})$ value in weakly deformed ${}^{38}\mathrm{S}$ but deviates significantly from that in spherical ${}^{36}\mathrm{S}$. This manifests that ${}^{37}\mathrm{S}$ is a weakly deformed rather than spherical nucleus.

Figure 1

Schematic representation of the energies of the first excited states in the $N=21$ isotones [3]. The insert indicates the relevant single-particle orbitals of proton and neutron.

Figure 2

Total projected spectrum of $\gamma$ rays measured by ${\mathrm{LaBr}}_3$ detectors. The full energy peaks of de-excited $\gamma$ rays of ${}^{37}\mathrm{S}$ is marked by red numbers. The 3103-keV $\gamma$ ray comes from ${}^{37}\mathrm{Cl}$ following the ${\beta }^{-}$ decay of ${}^{37}\mathrm{S}$.

Figure 3

The delayed time spectra (red markers and lines) of coincident $\beta$ and (a) 1583-, (b) 751-, and (c) 646-keV $\gamma$ rays; the $\beta -\gamma$ prompt time spectra (blue markers and lines) from ${}^{60}\mathrm{Co}$ source providing a reference standard.