Investigations of pairing in nuclei

NUCL 40

R. M. Clark, rmclark@lbl.gov, Nuclear Science Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, MS 88R0192, Berkeley, CA 94720-8101
In this presentation I will discuss two topics joined under the common theme of pairing in the nucleus. First, I will present a new description of the transition from a "normal" to a "superconducting" nucleus. Analytical solutions of the collective pairing Hamiltonian were found by using simple approximations to the potential in various limits. The approximate collective solutions are compared to the exact solutions of a two level model and good agreement is found. Comparison to experimental data on the Pb isotopes suggest that 208Pb is close to the critical-point of the pairing transition. Second, I will describe recent experiments using (3He,p) np-pair transfer reactions on N=Z nuclei to search for evidence of T=1 and T=0 collective np pairing. In particular, a radioactive beam of 44Ti was used to measure the relative transfer cross section to the lowest lying T=0 and T=1 states in 46V. There is no evidence of appreciable T=0 np-pair collectivity in this system.