beta(-) decay of neutron-rich Cl-45 located at the magic number N=28

Results from the study of the beta(-) decay of Cl-45, produced in the fragmentation of a 140-MeV/u Ca-48 beam, are presented. The half-life for 45Cl beta decay is measured to be 513(36) ms. The beta(-) and beta(-)1n decay of Cl-45 populated excited states in Ar-45,Ar-44, respectively. On the basis of gamma-ray singles and gamma-gamma coincidence data, decay schemes for the two daughter nuclei have been established. They are compared with shell model calculations using the FSU interaction. The low-lying negative parity states for Ar-45 are well described by a single particle (neutron) occupying orbitals near the Fermi surface, whereas neutron excitations across the N = 20 shell gap are needed to explain the positive-parity states which are expected to be populated in allowed Gamow-Teller beta decay of Cl-45. The highest beta feeding to the 5/2(+) state in Ar-45 from the ground state of Cl-45 points towards a 3/2(+) spin-parity assignment of the ground state of the parent over the other possibility of 1/2(+). The high Q(ss-) value of Cl-45 decay allows for the population of 1p1h states above the neutron separation energy in Ar-45 leading to positive parity states of Ar-44 being populated by removal of one neutron from the sd shell. The spin-parities of the excited levels in Ar-44 are tentatively assigned for the first time by comparison with the shell model calculations. The 2978 keV level of Ar-44 is identified as the excited 0(+) level which could correspond to a different configuration from the ground state.