Evidence for spherical-oblate shape coexistence in $^{87}\mathrm{Tc}$

Excited states in the neutron-deficient nucleus $^{87}$Tc have been studied via the fusion-evaporation reaction $^{54}$Fe($^{36}$Ar, 2$n$1p) $^{87}$Tc at 115 MeV beam energy. The AGATA γ -ray spectrometer coupled to the DIAMANT, NEDA, and Neutron Wall detector arrays for light-particle detection was used to measure the prompt coincidence of $\gamma$ rays and light particles. Six transitions from the deexcitation of excited states belonging to a new band in $^{87}$Tc were identified by comparing $\gamma$-ray intensities in the spectra gated under different reaction channel selection conditions. The constructed level structure was compared with the shell model and total Routhian surface calculations. The results indicate that the new band structure in $^{87}$Tc is built on a spherical configuration, which is different from that assigned to the previously identified oblate yrast rotational band.