Decay Spectroscopy of $^{129}$Cd

TL;DR

This study used advanced gamma-ray spectroscopy to explore the excited states of $^{129}$In following the decay of $^{129}$Cd, revealing new energy levels and transitions, and providing insights into the decay mechanisms and Gamow-Teller transition strengths.

Contribution

It reports the first observation of 32 new transitions and 7 new excited states in $^{129}$In, expanding the nuclear level scheme and analyzing decay pathways with improved experimental data.

Findings

32 new gamma transitions identified

7 new excited states discovered

Allowed Gamow-Teller transitions are more dominant than previously thought

Abstract

Excited states of $^{129}$In populated following the $\beta$-decay of $^{129}$Cd were experimentally studied with the GRIFFIN spectrometer at the ISAC facility of TRIUMF, Canada. A 480-MeV proton beam was impinged on a uranium carbide target and $^{129}$Cd was extracted using the Ion Guide Laser Ion Source (IG-LIS). $\beta$- and $\gamma$-rays following the decay of $^{129}$Cd were detected with the GRIFFIN spectrometer comprising the plastic scintillator SCEPTAR and 16 high-purity germanium (HPGe) clover-type detectors. %, along with the $\beta$-particles were detected with SCEPTAR. From the $\beta$-$\gamma$-$\gamma$ coincidence analysis, 32 new transitions and 7 new excited states were established, expanding the previously known level scheme of $^{129}$In. The $\log ft$ values deduced from the $\beta$-feeding intensities suggest that some of the high-lying states were populated by the $\nu 0 g_{7/2} \rightarrow \pi 0 g_{9/2}$ allowed Gamow-Teller (GT) transition, which indicates that the allowed GT transition is more dominant in the $^{129}$Cd decay than previously reported. Observation of fragmented Gamow-Teller strengths is consistent with theoretical calculations.