β decay of ⁹⁸Ag: Evidence for the Gamow-Teller resonance near ¹⁰⁰Sn

In two complementary measurements, a cubelike array of six Euroball-Cluster germanium detectors and a total-absorption γ spectrometer were used to investigate the β decay of ⁹⁸Ag, a three-proton-hole and one-neutron-particle nucleus with respect to the ¹⁰⁰Sn core. The half-life and Q_EC value of the decay were determined to be 47.7(0.3) s and 8200(70) MeV, respectively. A total of 438 γ rays (414 new) was observed, and 173 levels (163 new) in ⁹⁸Pd have been identified. The Gamow-Teller (GT) β-decay strength distribution from the total-absorption γ spectroscopy reveals a large GT resonance around 6 MeV with a width of about 2 MeV. The hindrance factor for the total GT strength, summed from the ground state up to 7.8 MeV excitation energy in ⁹⁸Pd, amounts to 4.6(6) with reference to a shell-model calculation which yields good agreement with the shape of the experimental GT resonance.