Search for diabolical pair transfer in two-neutron transfer reactions.

Abstract

The effects of proximity to a diabolic point on neutron transfer in nuclear physics is explored using the reactions [sup 206]Pb ([sup 156]Gd, [sup 154]Gd) [sup 208]Pb (presumed diabolic case) and [sup 206]Pb ([sup 156]Gd, [sup 158]Gd) [sup 204]Pb (nondiabolic case) at a laboratry bomdarding energy of 888 MeV. Deexcitation [gamma] rays were measured using a particle-particle-[gamma] triple-coincidence method. A comparsion of the spin distributions from each of the above reactions was used to search for a suppression of the [gamma]-ray yields that has been predicted within the cranked Hartree-Fock-Bogoliubov model for diabolical pair transfer. The latest calculations agree with the results of this experiment. The influence of diabolical pair transfer is more subtle than expected for the case of sharp backbending nuclei such as [sup 154]Gd. No clear evidence for diabolical pair transfer was observed within the sensitivity range of this experiment, nor was it possible to unambigously place the diabolical point between [sup 154]Gd and [sup 156]Gd.