Interacting boson-fermion model description of the positive high-spin states of the odd Er isotopes

The positive, high-spin states of the ^155-165Er isotopes are studied within the framework of the interacting boson-fermion model. The single fermion is assumed to be in the I = (13/2) orbit only. It was found that the calculated positive high-spin state energy spectra of the odd Er isotopes agree quite well with the experimental data. Also, the observed order reversal of the adjacent spin doublet states of the energy spectra for ^159-163Er has been successfully reproduced. The B(E2) values for ^157-163Er are calculated and compared with the experimental data.