Decay studies of Sr isotpes with high resolution and total absorption techniques

High Resolution measurements The beta/EC decay of 77,78Sr and 76,78Rb have been studied in this work. Measurements were carried out of the energies and intensities of the emitted gamma-rays and conversion electrons as well as gamma-gamma and gamma-X-ray coincidences in the decays of 77,78Sr, which have extended our knowledge of their decay schemes including spin and parity assignments to the levels populated in the daughter nucleus, 77Rb and 78Rb respectively. For the decay of 78Sr, 16 new levels and 44 new gamma-ray transitions have been identified. The very much improved experimental knowledge of the 78Rb levels populated in the decay and the strong link between the parent and the daughter states has allowed us to infer some possible level configurations by comparison with HF+BCS calculations using the SG2 Skyrme force. For the decay of 77Sr, 9 new levels and 15 new gamma-ray transitions have been identified. The levels in the low energy part of the level scheme have been discussed in terms of HF+BCS+QRPA calculations leading to an interpretation of their structure. Total Absorption measurements In addition, a study of the beta-decay of 77,78Sr and 76,78Rb using the Total Absorption Spectrometer (TAS) LUCRECIA at ISOLDE has been carried out. The beta feeding intensity and B(GT) distributions have been deduced from the analysis of the TAS data. The comparison of the B(GT) distribution of the decay 78Sr with theoretical calculations has confirmed the prolate shape. The B(GT) distribution of 77Sr has been interpreted using a very simple decay picture. General conclusions have been inferred for the odd-odd nuclei, 76Rb and 78Rb, based on a comparison with their corresponding even-even nuclei.