Multi-particle emission in the decay of $^{31}$Ar

G. T. Koldste , Bertram Blank (1) , M. J. G. Borge , J. A. Briz , M. Carmona-Gallardo , L. M. Fraile , H. O. U. Fynbo , J. Giovinazzo (1) , B. D. Grann , J. G. Johansen , A. Jokinen , B. Jonson , T. Kurturkian-Nieto (1) , J. H. Kusk , T. Nilsson , A. Perea , V. Pesudo , E. Picado , K. Riisager , A. Saastamoinen , O. Tengblad , J.C. Thomas (2) , J. van de Walle

1 NEX - Noyaux exotiques
2 GANIL - Grand Accélérateur National d'Ions Lourds

A multi-hit capacity setup was used to study the decay of the dripline nucleus 31Ar, produced at the ISOLDE facility at CERN. A spectroscopic analysis of the beta-delayed three-proton decay of 31Ar is presented for the first time together with a quantitative analysis of the beta-delayed two-proton-gamma-decay. A new method for determination of the spin of low-lying levels in the beta-proton-daughter 30S using proton-proton angular correlations is presented and used for the level at 5.2 MeV, which is found to be either a 3+ or 4+ level, with the data pointing towards the 3+. The half-life of 31Ar is found to be 15.1(3) ms. An improved analysis of the Fermi beta-strength gives a total measured branching for the beta-3p-decay of 3.60(44) %, which is lower than the theoretical value found to be 4.24(43) %. Finally the strongest gamma-transitions in the decay of 33Ar are shown including a line at 4734(3) keV associated to the decay of the IAS, which has not previously been identified.

Domaines: Physique Nucléaire Expérimentale [nucl-ex]

G. T. Koldste, Bertram Blank, M. J. G. Borge, J. A. Briz, M. Carmona-Gallardo, et al.. Multi-particle emission in the decay of $^{31}$Ar. Physical Review C, 2014, 89, pp.064315. ⟨10.1103/PhysRevC.89.064315⟩. ⟨in2p3-00950155⟩