06 v 1 7 J un 1 99 4 Orbital and Spin Magnetic Dipole Strength in a shell model calculation with ∆ N = 2 excitations : 8 Be

The magnetic dipole strength and energy-weighted strength distribution is calculated in 8 Be, as well as the separate orbit and spin parts. All ∆N =2 excitations over and above (and including) the configuration 0s 4 0p 4 are included. The interaction has a central, two-body spin-orbit and a tensor part. The energy-independent and energy-weighted orbital strength distribution is remarkably insensitive to the presence or absence of the spin-orbit or tensor interaction-not so the spin strength. The energy-weighted strength distribution can be divided into a low enegy and a high energy part. The high energy orbital part is somewhat less but close to the low energy part, in fair agreement with a prediction that they be equal by de Guerra and Zamick and by Nojarov. There is a wide plateau separating the low energy part from the high energy part.