New insight in the level structure of 153Er

The high-spin level structure of the 153Er nucleus has been reinvestigated by in-beam γ-ray and electron spectroscopy with (14N,pxn) reaction. Excitation energies, spin and parity assignments are unambiguously established for the two lowest isomers T1/2≅380 ns and T1/2≅10 ns. The characteristics of the third one (T1/2≅250 ns) at 5.2 MeV are still questionable but its main decay modes are better known. An extension of the level scheme is proposed up to 8.4 MeV. Experimental results have been discussed in terms of shell model multiplets and compared with the other structures observed in N=85 neighbouring nuclei. (orig.)