E1 isobaric analogue resonances of strongly deformed nuclei in (e,e′p) reactions

The cross sections of the (e, e′p) reaction on the deformed nuclei ¹⁵⁹Tb, ¹⁶⁵Ho, ¹⁶⁹Tm, ¹⁷⁵Lu and ¹⁸¹Ta have been measured in the vicinity of the ground isobaric analogue state. Resonances corresponding to the E1 isobaric analogue states are found and displacement energies are calculated from these resonances. These energies are smaller than those obtained from proton scattering, which shows their dependence on the reaction type. The radiative widths of the E1 transitions of the isobaric analogue resonances were obtained. The ratio of these to the single-particle width calculated with the Nilsson model is order of 0.1–1 for non-spin-flip transitions and more than 10² for spin-flip transitions. These results are similar to those of the spherical nuclei ¹³⁹La, ¹⁴¹Pr, ²⁰⁷Pb and ²⁰⁹Bi.