SHAPES, ELECTROMAGNETIC PROPERTIES AND ENHANCED E1 STRENGTH IN LU-169

Rotational bands in Lu-169 previously observed via (p, 3n) and (alpha, 4n) reactions were extended by 8-14 units of angular momentum using t he Sm-154(F-19, 4n) reaction and the Nordball detector array. By analy sis of gammagamma coincidence relations and gamma-ray angular correlat ions we have established the [541]1/2-, alpha = +1/2 band to 57/2HBAR, the [514]9/2- bands to 47/2HBAR, the [404]7/2+ bands to 53/2HBAR and the [411]1/2+, alpha = 1/2 to 47/2 (55/2) h. The bands belonging to th e [411]1/2+ and [402]5/2+ configurations with alpha = +1/2 appear to b e rather mixed in the low spin region. One of these bands is establish ed to 45/2 (49/2) units of spin. The transitions interconnecting the s ignature partners, in the bands based on the [514]9/2-and [404]7/2+ Ni lsson orbitals, as well as in and between the strongly mixed [411]1/2 and [402]5/2+ bands are compared to particle-rotor model calculations . By DSAM analysis, lifetimes and thereby transition quadrupole moment s for the band built on the configuration h9/2[541]1/2-, alpha = +1/2 could be extracted. The abnormal alignment pattern at the vi13/2 cross ing for the h9/2[541]1/2- band is analysed in terms of a difference in both deformation and neutron pairing compared to the other less polar izing configurations. The influence of octupole modes on the strength of observed [411]1/2+ double-line arrow pointing right [541]1/2- E1 tr ansitions as well as on observed spin-flip, [514]9/2- double-line arro w pointing right [404]7/2+, E1 transitions is investigated theoretical ly and compared to the experimental data.