43Ar and 44Ar

Abstract The half-lives andγ-ray spectra of 43 Ar and 44 Ar have been measured. The first information on the half-life of 43 Ar was obtained using the reaction Ti(p, spallation) 43 Ar and the isotope separator on-line facility (ISOLDE) at the CERN 600 MeV synchro-cyclotron. Precise measurements of the half-lives and γ-ray energies, and also of the relative γ-ray intensities were made on samples produced by the reaction V(p, spallation) 43,44 Ar with 600 MeV protons followed by mass separation in the CERN off-line isotope separator. The half-life of 43 Ar is 5.37 ± 0.06 min, and that of 44 Ar is 11.87 ± 0.05 min. The γ-speetrum accompanying the decav of 43 Ar is complex; 18γ-rays were found. The γ-spectrum accompanying 44 Ar decay has only five γ-rays. Partial decay schemes for 43 Ar and 44 Ar are presented.