1 Risø National Laboratory, Risø National Laboratory for Sustainable Energy, Technical University of Denmark2 Risø National Laboratory for Sustainable Energy, Technical University of Denmark
The low energy gamma-rays from neutron-capture in Lu 175 and Lu 176 have been investigated by means of the bent crystal-spectrometer at the DR-3-reactor at Risø. From the transitions in Lu 177 3 rotational bands have been determined. The levels of the (404)K=7/2+ groundstate rotational band are: 121,62 keV (I=9/2), 268,79keV (I=11/2), 440,66 keV (I=13/2), 636,22 keV (I=15/2), 854,34 keV (I=17/2). The level-sequence of the (514)K=9/2−-band is: 150,39 keV (I=9/2), 288,99 keV (I=11/2), 451,49 keV (I=13/2), 637,05 keV (I=15/2) and 844,88 keV (I=17/2). At 457,92 keV is the basis for the (402)K=5/2+-band the higher levels of which are 552,05 keV (I=7/2), 671,89 keV (I=9/2), 816,63 keV (I=11/2), 985,23 keV (I=13/2), 1176,73keV (I=15/2) and probably 1389,5 keV (I=17/2). The energies of the levels apart from the 1389 keV-level have an accuracy of 7×10−5. The energy differences between the 3 bands agree very well with the values expected from the Bohr-Mottelson-formulaE=A·I(I+1)+B·I 2(I+1)2. The calculated branching-ratios within the 3 bands are in fairly good agreement with the experimental values. Theg K -factors have been determined for 2 bands: It was found that for the (514)-bandg K =1,16±0,04 and for the (402)-bandg K =1,33±0,07.
Zeitschrift Für Physik, 1965, Vol 184, Issue 2, p. 153-174