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G. T. Koldste et al. ; 10 pags. ; 14 figs. ; 4 tabs. ; PACS number(s): 23.40.Hc, 27.30.+t ; A multihit 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 β-delayed three-proton decay of 31Ar is presented for the first time together with a quantitative analysis of the β-delayed 2pγ decay. A new method for determination of the spin of low-lying levels in the βp daughter 30S using proton-proton angular correlations is presented and used to determine that the spin of the 5.2-MeV level is most likely 3+ with 4+ also possible. The half-life of 31Ar is found to be 15.1(3) ms. An improved analysis of the Fermi β strength including the β3p-decay mode gives a total measured branching ratio of 3.60(44)%, which is lower than the theoretical value found to be 4.24(43)%. Finally, a previously unidentified γ transition from the isobaric analog state in the decay of 33Ar has been found. © 2014 American Physical Society. ; This work was supported by the European Union Seventh Framework through ENSAR (Contract No. 262010). This work was partly supported by the Spanish Funding Agency under Projects No. FPA2009-07387, No. FPA2010-17142, and No. AIC-D-2011- 0684, by the French ANR (Contract No. ANR-06-BLAN- 0320). ; Peer Reviewed

5 pags. ; 7 figs. ; Open Access funded by SCOAP3 - Sponsoring Consortium for Open Access Publishing in Particle Physics ; © 2014 The Authors. We present for the first time precise spectroscopic information on the recently discovered decay mode β-delayed 3p-emission. The detection of the 3p events gives an increased sensitivity to the high energy part of the Gamow-Teller strength distribution from the decay of 31Ar revealing that as much as 30% of the strength resides in the β3p-decay mode. A simplified description of how the main decay modes evolve as the excitation energy increases in 31Cl is provided. ; This work was supported by the European Union Seventh Framework through ENSAR (Contract No. 262010), it was partly supported by the Spanish Funding Agency under Projects No. FPA2012-32443, No. FPA2010-17142, CPAN ConsoliderCSD-2007-00042, and No. AIC-D-2011-0684. ; Peer Reviewed