Shell model analysis of intruder states and high- K isomers in the fp shell

Abstract

We perform a systematic shell-model study of collective intruder structures and fully aligned high-spin states in nuclei from the lower-fp shell in the sdfp configuration space. We analyze the intruder structures associated with the 1p-1h cross-shell excitations from the sd shell that have been observed in several nuclei from this region, including 44Ti and 44Sc. We compare the shell-model calculations to the recent mean-field work (H. Zdunczuk, W. Satula, R.A. Wyss, nucl-th/0408018) and experimental data (M. Lach, J. Styczen, private communication). The high-spin behavior may be understood in terms of the competing cross-shell proton and neutron excitations. The interplay between proton and neutron intruder states is reflected in the angular-momentum dependence of electromagnetic rates.