Shell-model calculations in the 4He system

Abstract

Structure calculations for the 4He system are performed in both [Formula: see text] and [Formula: see text] model spaces. The results of these calculations suggest that a reasonable level spectrum can be obtained with the Sussex interaction if binding energy considerations are neglected. Imposing binding energy requirements leads to distortions in the level spectrum. The T = 1 levels and selected T = 0 levels are reasonably described by the bare Sussex interaction (b = 1.4 fm). The (0+, 0) 20.1 MeV level and (2−, 0) 22.1 MeV level are best described by the b = 1.80 fm and b = 1.60 fm Sussex interactions, respectively. Attempts to arbitrarily vary individual relative matrix elements do not improve the (0+, 0) spectrum. The resulting calculations suggest that an adequate description of the 4He level spectrum is not possible if a single oscillator length parameter is used for all levels. The results also emphasize the difficulty of performing structure and reaction calculations in a consistent manner, because different b values are required for binding, rms radius, or level considerations. The choice of b is not obvious and should be determined by solution criteria.