High-spin states in 24Mg and upper limits for particle spectroscopy of high spins by heavy-ion compound reactions

Abstract

Abstract High-spin states in 24Mg have been investigated by the reaction 10B(16O, d)24Mg up to E ∗ ≈ 24 MeV . High-spin states with I ≧ 9 have been identified at E ∗ = 19.20, 20.26, 20.8, 21.6, 23.1, and 23.5 MeV . The 10+ yrast state in 24Mg is probably located at 20.26 MeV. The upper limits with respect to spin and excitation energy of the applicability of heavy-ion compound reactions for particle spectroscopy of high-spin states are discussed. The main limitations result from the increasing continuum and from a decrease of the high-spin selectivity when the final spins approach the critical angular momentum for compound-nucleus formation. It will be shown that the difficulty in the analysis of the experiments arising from the decreasing probability of finding isolated yrast states at high excitation energies, i.e. from the increasing level density, can be overcome in such experiments. The decrease in the high-spin selectivity of the total cross section is compensated for spins up to Jmax by the fact that the shape of the angular distributions depends on the final spin for states with I ∼ Jmax. This is caused by the decreasing alignment of the final nucleus with decreasing values of |I − Jmax| and can be used for high-spin spectroscopy.