The Gamow-Teller beta decay of neutron-deficient even isotopes of tin

With the use of the⁵⁸Ni+⁵⁰Cr fusion-evaporation reaction and chemically selective on-line mass separation, the EC/β⁺ decay of¹⁰⁴Sn was studied by γ-ray and conversionelectron spectroscopy. In the course of these studies, a new 15.7-s isomeric state of¹⁰⁴In was observed. Reinvestigation of the β-decays of the two heavier even isotopes of tin, produced in the⁵⁸Ni+⁵⁸Ni reaction and mass separated without chemical discrimination, brought new information on the decay of¹⁰⁶Sn and¹⁰⁸Sn. The Q_EC values of¹⁰⁴Sn,¹⁰⁶Sn and¹⁰⁸Sn were determined to be 4550_-250⁺³⁰⁰keV, 3200±100 keV and < 2270 keV, respectively. In the data analysis, the emphasis is put on the identification of the 0⁺ → 1⁺ Gamow-Teller β transitions and determination of their strengths. For^104-110Sn, the total Gamow-Teller strengths are measured to be 20% to 30% of that predicted by the single-particle shell model with the inclusion of pairing correlations and core polarization. Predictions of the decay properties of the as yet unobserved¹⁰²Sn and¹⁰⁰Sn are made.