Giant Gamow-Teller Excitations in ¹⁰⁴Cd

Abstract

The decay of ¹⁰⁴In is since long a puzzle, not only because of the significant deviation of the measured Q_EC value ¹) from the mass tables of Wapstra and Audi ²) but also because of the inconsistenties in the decay scheme: the β⁺/EC decay of the high-spin groundstate (I = 5, 6 or 7) feeds, according to the published decay scheme ³), levels with spins ranging from spin 2 up till 8 with log ft values between 5.5 and 6.9. By studying the β spectrum of ¹⁰⁴In with a solid-state beta detector and by taking extensive γ-γ coincidences at the LISOL on-line isotope separator it becomes clear that the published endpoint energy ¹) and level scheme ³) are quite correct but that the deduced Q_EC value, β feedings and log ft values are completely wrong. This is due to a strong β⁺/EC feeding to a group of levels around 5.5 MeV: in this region far off stability near the mirror nucleus ¹⁰⁰Sn the β⁺/EC decay is strongly influenced by the Gamow-Teller Resonance.