Multipole Analysis of Particle-Particle or Particle-Hole Multiplets

Recent data on particle-hole multiplets in Bi208 have been analyzed in terms of the Racah multipole decomposition. The resulting multipole coefficients are very similar for the various multiplets. A comparison with other known multiplets in Cl38, K30, Sc42, Sc48, Sc50, Nb92, and Bi210 also shows a remarkable similarity. These empirical results show that the spectra of such multiplets are determined reasonably well by one set of multipole coefficients, independent of the single-particle orbits involved. It has been pointed out by Kurath that a simple δ-function two-body force with spin exchange fits these average multipole coefficients as well as more complicated interactions.