Decay properties of ground-state and isomer of ¹⁰³In

Abstract

The β-decay properties of ground-state and isomer of ¹⁰³In were investigated by means of γ-ray spectroscopy. The half-lives of ^103gIn and ^103mIn were determined to be 60 ± 1 s and 34 ± 2 s, respectively. Out of 149 γ transitions ascribed to the decay of ^103gIn, 104 have been placed in a decay scheme including 55 excited states of ^103gCd. The main part of the resulting distribution of the Gamow-Teller strength B(GT) is associated with the feeding of ¹⁰³Cd levels at excitation energies around 3 MeV. This observation can be interpreted as a sign of dominant feeding of three-quasiparticle states in ¹⁰³Cd, which correspond to the 1⁺(πg ⁻¹_9/2 , vg_7/2)⊗πg_9/2 shell-model configuration spread over many levels. The sum of the B(GT) values deduced from the present γ-ray data amounts to 0. 34, which provides a lower limit to the total Gamow-Teller strength. The B(GT) distribution for ¹⁰³In decay is compared to the corresponding experimental results for ^105,107,109In and to theoretical predictions for ^99,101In. The latter were calculated by using an advanced spherical shell model. The β-branching ratio for the ^103mIn decay is estimated and compared with the relevant values for the neighbouring indium isotopes including ¹⁰¹In whose half-life was determined to be 14. 9 ± 1.2 s.