THE SHELL-MODEL FOR T = 0 AND T = 1 STATES IN THE MIDDLE OF THE SD SHELL

Spectroscopic properties of several hundreds of T = 0 and T = 1 states of A = 28 and 30 nuclei have been compared with the results of a shell-model calculation (untruncated sd shell). For A = 28 the calculation also includes gamma-ray branching and mixing ratios, lifetimes, spectroscopic factors, proton widths and log ft values for the (P(beta+)Si)-P-28-Si-28 decay. Uncertainties in spin, parity and isospin determinations have been resolved and parent-analogue relations have been established. Errors have been spotted in the analysis and evaluation of experimental data. A clear indication has been found of intruder states in Si-28 and P-30. The present work has provided a good idea as to the reliability of the shell model in the middle of the sd shell. With previous results for A = 26 taken along one arrives at an average error of 145 keV in the theoretical energies. The averaged absolute spread in the ratio of theoretical over experimental strengths amounts to a factor 1.9 for isoscalar E2 transitions, and to a factor 2.3 for isovector M1 transitions.