Speaker
Description
A recent survey [1] of potential candidates for spherical vibrational motion [2] concluded that very few passed the criteria; of those that did, $^{98,100}$Ru were the most promising. However, in part this may have been due to the lack of detailed spectroscopic data for $^{98,100}$Ru. In order to remedy this, we have performed a high-statistics measurement of the β decay of $^{98,100}$Rh using the newly commissioned β decay Tape Station at iThemba labs located near Cape Town, South Africa. Activities of $^{98,100}$Rh were produced using fusion evaporation reactions of $^{14}$N and $^{16}$O beams on an $^{89}$Y target, which was then transported from the irradiation station to a counting station. The counting station consisted of 4 clover-type high-purity germanium detectors, augmented by a TIGRESS detector, a plastic scintillator for the β particles, and an in-vacuum Si(Li) detector for conversion electrons. The decay of $^{98}$Rh and $^{100}$Rh to $^{98}$Ru and $^{100}$Ru was the first measurement to be completed on this new facility. Very high-statistics data sets were collected for $^{98,100}$Ru, resulting in considerable expansions of their decay schemes. In this presentation, we concentrate on the results for $^{98}$Ru from the analysis of the γ-γ coincidence matrix.
A main focus of this work has been on possible states associated with the first excited $0^+$ state, the $0_{2}^{+}$ level. Several weak E2 transitions $–$ the 495 keV $(2^{ +}_{3}→0_{2}^{+})$, 402-keV $(2_3^+→2_2^+)$ and 419-keV $(2_3^+→4_1^+)$, were newly observed. The E2 transition to the $0_2^+$ state possesses the largest relative B(E2) value, strongly suggesting that the $2^{+}_{3}$ state is a band member of the excited $0^+_2$ band. We have also observed a candidate level for the 4+ rotational band member, suggesting that $^{98}Ru$ possesses a more-deformed excited $0^+$ band coexisting with a less-deformed ground state.
Details of the analysis of the $^{98}Rh$ decay to date will be given.
[1] P.E. Garrett, J.L. Wood, and S.W. Yates, Phys. Scripta 93, 063001 (2018).
[2] J. Kern et al., Nucl. Phys. A593, 21 (1995).
