Spectroscopic studies of neutron-rich 129Sn and 80Ge nuclei using the GRIFFIN spectrometer

Spectroscopic studies provide information about the structure of nuclei. Information that, in turn, serves to inform theoretical models and astrophysical studies.Recent work using the GRIFFIN spectrometer at TRIUMF has uncovered novel information in two isotopes, $^{129}$Sn and $^{80}$Ge, which lie close to the two magic nuclei: $^{132}$Sn and $^{78}$Ni, respectively. The work on $^{129}$Sn observed 31 transitions and 9 excited states for the first time, populated through the $\beta$-decay of $^{129}$In. Most notably, this experiment was the first to observe the $\beta$-decay of the $(29/2^{+})$ 1911-keV isomer of $^{129}$In. The work on $^{80}$Ge searched for a previously observed $0^{+}$ state at 639-keV, just below the $2^{+}$ 659-keV excited state, through the $\beta$-decay of $^{80}$Ga. The presence of the former was proposed as evidence for low-energy shape coexistence in $^{80}$Ge, in the region around doubly-magic $^{78}$Ni, though further signatures for the presence of this state were missing. The GRIFFIN experiment was unable to observe this state, despite using a superior detector system and observing higher statistics . The nonobservation, coupled with theoretical calculations performed, led to the conclusion that this $0^{+}$ 639-keV does not exist. Furthermore, the analysis observed, for the first time, 66 excited states and 157 $\gamma$-ray transitions, which were added to the known $^{80}$Ge level scheme. The data here presented will serve to improve upon existing nuclear structure theories and will inform future applications of nuclear science to fields such as astrophysics.