β− decay of neutron-rich Cl45 located at the magic number N=28

Results from the study of the β− decay of Cl45, produced in the fragmentation of a 140-MeV/u Ca48 beam, are presented. The half-life for Cl45β decay is measured to be 513(36) ms. The β− and β−1n decay of Cl45 populated excited states in Ar45,44, respectively. On the basis of γ-ray singles and γ−γ 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 Ar45 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 β decay of Cl45. The highest β feeding to the 5/2+ state in Ar45 from the ground state of Cl45 points towards a 3/2+ spin-parity assignment of the ground state of the parent over the other possibility of 1/2+. The high Qβ− value of Cl45 decay allows for the population of 1p1h states above the neutron separation energy in Ar45 leading to positive parity states of Ar44 being populated by removal of one neutron from the sd shell. The spin-parities of the excited levels in Ar44 are tentatively assigned for the first time by comparison with the shell model calculations. The 2978 keV level of Ar44 is identified as the excited 0+ level which could correspond to a different configuration from the ground state.4 MoreReceived 28 April 2023Revised 5 July 2023Accepted 26 July 2023DOI:https://doi.org/10.1103/PhysRevC.108.024312©2023 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBeta decayLifetimes & widthsNuclear structure & decaysProperties39 ≤ A ≤ 58TechniquesRadioactive beamsNuclear Physics