Kavatsyuk M. Total-absorption studies of the Gamow-Teller transitions in light-tin isotopes

The thesis is dedicated to investigations of the Gamow-Teller (GT) strength of exotic nuclei in 100Sn region, namely 103,105Sn. The GT strength distribution was studied in beta-decay by means of total-absorption spectroscopy. The use of this method allowed to obtain the total GT strength for 103,105Sn isotopes. Obtained experimental distributions were compared with theoretical predictions based on the quasiparticle shell-model with residual interaction. It was shown that the model reproduce the general resonance structure of the strength distribution. However, theoretical predictions do not reproduce position and width of the measured giant GT resonance (even for isotopes located very close to the doubly-magic nucleus 100Sn). Moreover, the spectroscopic characteristics of 103,105Sn nuclei like beta-decay energy, electron-capture contribution to beta-decay, branching ratio of the beta-delayed proton branch and half-life were measured. For the data evaluation procedure, a new method of digital pulse-shape analysis for the total-absorption spectrometer was developed that allowed to identify short-lived isomeric states in daughter nuclei.