Hindered Gamow-Teller Decay to the Odd-Odd N = Z (62)~Ga: Absence of Proton-Neutron T = 0 Condensate in A = 62

摘要

Search for a new kind of superfluidity built on collective proton-neutron pairs with aligned spin is performed studying the Gamow-Teller decay of the T = 1,J~π = 0~+ ground state of ~(62)Ge into excited states of the odd-odd N = Z nucleus ~(62)Ga. The experiment is performed at GSI Helmholtzzentrum fuer Shwerionenforshung with the ~(62)Ge ions selected by the fragment separator and implanted in a stack of Si-strip detectors, surrounded by the RISING Ge array. A half-life of T_(1/2) = 82.9(14) ms is measured for the ~(62)Ge ground state. Six excited states of ~(62)Ga, populated below 2.5 MeV through Gamow-Teller transitions, are identified. Individual Gamow-Teller transition strengths agree well with theoretical predictions of the interacting shell model and the quasiparticle random phase approximation. The absence of any sizable low-lying Gamow-Teller strength in the reported beta-decay experiment supports the hypothesis of a negligible role of coherent T = 0 proton-neutron correlations in ~(62)Ga.