Observations of the Gamow-Teller resonance in the rare-earth nuclei above Gd 146 populated in β decay

The rare-earth region of the nuclear table around the quasi-doubly magic nucleus Gd146 is one of the very few places in which the Gamow-Teller (GT) resonance can be populated in β decay. The appropriate technique to study such a phenomenon is total absorption spectroscopy, thanks to which one can measure the B(GT) distribution in β-decay experiments even when it is very fragmented and lies at high excitation energy in the daughter nucleus. Results on the GT resonance measured in the β decay of the odd-Z, N=83 nuclei Tb148, Ho150, and Tm152 are presented in this work and compared with shell-model calculations. The tail of the resonance is clearly observed up to the limit imposed by the Q value. This observation is important in the context of the understanding of the "quenching" of the GT strength.