Energy shifted level densities in rare earth region - art. no. 067302

The energy shift between the level densities of the even-odd and even-even isotopes Dy-161.162 and Yb-171.172 is measured as a function of excitation energy. The results are compared with predictions from various semiempirica l models. The energy shift procedure works well for excitation energies bet ween 3.5 and 7 MeV in the even-even nucleus, yielding a relative energy shi ft close to the experimental pairing gap parameter Delta.