Decay studies of exotic nuclei near the Z=N line

Abstract

This thesis is based on beta-decay studies performed during 1994-1997 in three mass-separator facilities in Europe. Most of the experiments have been done at the ISOLDE facility at CERN. In addition, experiments were carried out at the GSI On-Line Mass Separator in Darmstadt and the Heavy-ion Ion-Guide Isotope Separator On-Line (HIGISOL) in Jyväskylä. The production methods used were fusion-evaporation reactions at GSI and JYFL as well as fragmentation and spallation at ISOLDE. Production of refractory elements from Y to Mo was proved successful using the heavy-ion fusion-evaporation reactions in connection with the ion-guide technique at JYFL. These complementary facilities offered means to obtain new information on several beta-decaying isotopes along Z = N line in the region A = 55 - 85 by using beta-delayed gamma and proton spectroscopy. The Garnow-Teller strengths for the low-energy final states could be determined for four isotopes leading to a comparison of the results of the beta-decay and charge-exchange reaction studies in the case of 58Zn. The systematics of the ground-state Garnow-Teller matrix elements could be extended for the mirror decays in fp shell. The proton drip line was reached for Rb isotopes and new information was obtained for refractory elements above A = 80. In addition to the nuclear structure studies, the output of these studies can be straightly used as an input for the astrophysical reaction flow calculations.