PYGMY GAMOW-TELLER RESONANCE IN THE N = 50 REGION: NEW EVIDENCE FROM STAGGERING OF β-DELAYED NEUTRON-EMISSION PROBABILITIES OBSERVED WITH TETRA

摘要

We report on the P_n measurements of the ~(82,83,84)Ga (N = 51, 52, 53) precursors performed in one single experiment using the ~3He neutron-counter TETRA at the ALTO facility in Orsay. Altogether our results for the three A = 82, 83 and 84 Ga isotopes point towards a sizable P_n staggering in the N = 50 region, similar to the one already known in the N = 28 region, hinting at a similar mechanism. We will discuss the possible microscopic origin of this behavior i.e. the existence in the N = 50 region of a low-lying component of the so called Pygmy Gamow-Teller Resonance, already well established at Z = 36, and persisting towards ~(78)Ni.