New insights in the first backbending region of heavy Dy isotopes

Summary The 7 Li-induced incomplete fusion reaction 158/160 Gd( 7 Li,p(d,t)xn) (beam energy 56 MeV) has been used to investigate in detail the first backbending region of the heavy stable Dy nuclei 160/162 Dy. In 162 Dy, the measured low interaction strength between the ground band and the Stockholm band of | V gs | ≈ 17 keV confirms the predicted existence of a node in the interaction strength for nuclei with neutron number between N = 96 and N = 98, which has not been accessed earlier. The crossing frequency between the ground band and the Stockholm band in 162 Dy was measured to be hw c = 320 keV, which is about 40 keV higher than the expected value of hw c = 280 keV known from other nuclei in this mass region. In 160 Dy, an yrare band could be established for the first time in a nucleus with a very large interaction strength. From fits to level energies as well as from branching ratios, an interaction strength of | V gs | ≈ 220 keV was extracted.