Ground-state beta -decay spectroscopy of Ta-187

Beta-decay spectroscopy of the Ta-187 ground state was performed at the KEK Isotope Separation System. beta-delayed gamma rays corresponding to the previously reported in-beam transitions were observed. The beta-decay half-life of the Ta-187 ground state was determined to be 283(10) s by analyzing a time spectrum of beta-gamma coincidence events. The beta-decay branching ratio and log(ft) values were evaluated for the first time. Based on the newly evaluated log(ft) values of >6.0 and a decay scheme, spin-parity values of I-pi = 7/2(+) originating from the odd-proton orbit pi 7/2[404] were assigned with high confidence, which is consistent with the systematics of neighboring odd-A nuclides.