Speaker
Description
$^{71}$Kr was produced through the fragmentation of a $^{78}$Kr primary beam at the RIKEN-RIBF facility in Japan, in order to have the first comprehensive study of its $\beta$-decay leading to its mirror counterpart ($^{71}$Br). The $\beta$-decay of $^{71}$Kr has a significance from the astrophysical point-of-view, as it is a waiting point of the rp-process [1]. The question of the ordering of the ground state doublet of $^{71}$Kr also remains open, with spin-parities 5/2$^{-}$ and 1/2$^{-}$ and an energy difference of 10 keV for $^{71}$Br [2].
The fragments of $^{78}$Kr were identified using standard $\Delta\text{E-B}\rho$-ToF method [3]. A double-sided silicon strip array (WAS3ABi) was used for the implant and decay station [4]. The $\gamma$-rays were measured by a surrounding HPGe cluster array (EURICA) [5].
One of the main goals of the analysis was to derive the half-life of the $\beta$-decay using independent methods to rule out systematic uncertainties. We have used three methods: 1) Bateman-fit of implant-$\beta$ time correlations, 2) exponential fit of implant-($\beta\gamma$) time correlations of verified $\gamma$-transitions, 3) exponential fit of implant-proton time correlations of $\beta$-delayed prompt proton emission.
The other goal was to build the decay-scheme of the $\beta$-decay. Level ordering and $\gamma$-transition intensities were validated using $\gamma\gamma$-coincidences and the balance of in- and outgoing $\gamma$-feeding of levels. Levels with log$ft<$ 6 have been identified and placed in the level-scheme, including 8 new levels and 26 new $\gamma$-transitions.
The probability of proton emission was also measured with a 50-fold increased precision compared to the earlier experimental value of [6]. The details of the analysis, the preliminary results and an outlook on theoretical interpretations will be presented.
