Decay studies of the long-lived states in ${}^{186}$Tl

Abstract

Decay spectroscopy of the long-lived states in ${}^{186}$Tl has been performed at the ISOLDE Decay Station at ISOLDE, CERN. The $\alpha$ decay from the low-spin $(2^{-})$ state in ${}^{186}$Tl was observed for the first time and a half-life of $3.4_{-0.4}^{+0.5}$ s was determined. Based on the $\alpha$-decay energy, the relative positions of the long-lived states were fixed, with the $(2^{-})$ state as the ground state, the $7^{(+)}$ state at 77(56)~keV and the $10^{(-)}$ state at 451(56) keV. The level scheme of the internal decay of the ${}^{186}$Tl($10^{(-)}$) state ($T_{1/2}=3.40(9)$ s), which was known to decay solely through emission of 374 keV $\gamma$-ray transition, was extended and a lower-limit for the $\beta$-decay branching $b_{\beta }>5.9(3)\%$ was determined. The extracted retardation factors for the $\gamma$ decay of the $10^{(-)}$ state were compared to the available data in neighboring odd-odd thallium isotopes indicating the importance of the $\pi d_{3/2}$ shell in the isomeric decay and significant structure differences between ${}^{184}$Tl and ${}^{186}$Tl.

10 pages, 12 figures

References in corpus (2)

• Shape staggering of mid-shell mercury isotopes from in-source laser spectroscopy compared with Density Functional Theory and Monte Carlo Shell Model calculations
• Atomic mass measurements of short-lived nuclides around the doubly-magic 208Pb

Cited by in corpus (1)

• Simultaneous $\gamma$-ray and electron spectroscopy of ${}^{182,184,186}$Hg isotopes