Nuclear shell model and interacting boson fermion approximation

The Interacting Boson-Fermion Model (IBFM) hamiltonian is derived starting from the shell-model interaction, by a straightforward extension of the Otsuka, Arima and Iachello mapping procedure to odd-mass systems. Employing a single j-shell model and identical many nucleon systems, systematic studies of spectra giving the comparison in the shell-model, SD pair truncated model and IBFM are carried out: (i) for various proportions of monopole pairing and Q·Q interactions which simulate vibrational-rotational transition; (ii) for a particular combination of these interactions together with the quadrupole pairing interaction, which conserves seniority.