2018 Impact factor 2.481
Hadrons and Nuclei
Eur. Phys. J. A 16, 313-329 (2003)
DOI: 10.1140/epja/i2002-10105-x

Beta-decay of the $\mth{N=Z}$ nucleus $\chem{^{72}Kr}$

I. Piqueras1, 2, M.J.G. Borge1, Ph. Dessagne2, J. Giovinazzo2, A. Huck2, A. Jokinen3, A. Knipper2, C. Longour2, G. Marguier4, M. Ramdhane3, V. Rauch2, O. Tengblad1, 3, G. Walter2, Ch. Miehé2 and the ISOLDE Collaboration3

1  Instituto de Estructura de la Materia, CSIC, Serrano 113bis, E-28006 Madrid, Spain
2  Institut de Recherches Subatomiques, UMR 7500 CNRS-IN2P3 et Université Louis Pasteur, 23 rue du Loess, B.P. 28, F-67037 Strasbourg Cedex 2, France
3  ISOLDE, Division EP, CERN CH-1211 Geneva, Switzerland
4  Institut de Physique Nucléaire, Université Claude Bernard-Lyon I, F-69622 Villeurbanne Cedex, France

borge@pinar2.csic.es

(Received: 7 February 2002 / Revised version: 14 October 2002 / Published online: 6 March 2003)

Abstract
The beta-decay of the N=Z, even-even nucleus $\chem{^{72}Kr}$ has been studied at the ISOLDE PSB facility at CERN. Measurements of $\beta\gamma$ and $\beta\gamma\gamma$ coincidences have enriched the decay scheme of the daughter nucleus $\chem{^{72}Br}$ with 27 new low spin levels. A more precise half-life of T1/2=17.1(2) s has been determined. Strong feeding to the $\chem{^{72}Br}$ ground state is established yielding an unambiguous $J^{\pi}$ = 1 + assignment for this state. Candidates for the $\chem{^{72}Br}$ 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.

PACS
21.10.Hw - Spin, parity, and isobaric spin.
23.20.Lv - Gamma transitions and level energies.
23.40.Hc - Relation with nuclear matrix elements and nuclear structure.
27.50.+e - $59 \leq A \leq 89 $ .

© Società Italiana di Fisica, Springer-Verlag 2003