Systematic study of nuclear β decay

{β}-decay properties of nuclei are studied in the framework of proton-neutron quasiparticle random-phase approximation with a schematic Gamow-Teller residual interaction. Particle-hole and particle-particle terms of the separable Gamow-Teller force are consistently included for both β⁺ and β^- directions, and their strengths are fixed as smooth functions of mass number A of nuclei in such a way that the calculation reproduces observed {β}-decay properties of nuclei. Using the fixed interaction strengths, {β}-decay half-lives of nuclei up to A=150 are calculated, and generally good agreement with experiment is obtained. A schematic force which is relevant to the unique first-forbidden decay is also included in a similar way to the Gamow-Teller force, and its effects are studied. {} 1996 The American Physical Society.