Beta-decay of the N = Z nucleus ⁷²Kr

The beta-decay of the N = Z, even-even nucleus Kr-72 has been studied at the ISOLDE PSB facility at CERN. Measurements of betagamma and,betagammagamma coincidences have enriched the decay scheme of the daughter nucleus Br-72 with 27 new low spin levels. A more precise half-life of T-1/2 = 17.1(2) s has been determined. Strong feeding to the Br-72 ground state is established yielding an unambiguous J(pi) = 1(+) assignment for this state. Candidates for the Br-72 g.s. wave function are discussed in the framework of a self-consistent deformed mean-field calculation with SG2 Skyrme force and pairing correlations. A search for beta-delayed particle emission was made and an upper limit of 10(-6) for this decay branch obtained. The cumulated experimental level density of 1(+) states has been fitted with the constant temperature formula. The comparison indicates that most likely all 1(+) levels up to 1.2 MeV have been observed in this investigation. The corresponding nearest-neighbour level spacing does not follow a Poisson distribution. The Gamow-Teller strength distribution is compared, in terms of nuclear deformation, with different calculations made in the framework of the quasiparticle random phase approximation.