Abstract
A segmented Si-telescope and HPGe array, STARS-LIBERACE, was used to study the 156Gd(p,tγ)154Gd direct reaction by particle-γ coincidence spectroscopy. New cross sections with a 25- MeV proton beam are reported and compared to previous (p,t) and (t,p) studies. Furthermore, additional evidence for coexisting Kπ = 0+1 , 2+1 and 0+2 , 2+2 configurations at N = 90 is presented. Direct and indirect population patterns of the low-lying states are also explored. Review of the new and existing evidence fa- vors an interpretation based on a configuration-dependent pairing interaction. The weakening of monopole pairing strength and an increase in quadrupole pairing strength could bring 2p-2h 0+ states below 2∆. This may account for a large number of the low-lying 0+ states observed in two-nucleon transfer reactions. A hypothesis for the the origin of the 0+2 and 0+3 states is provided.
