The cross section for α-particle emission in the He6+Bi209 reaction at energies near the Coulomb barrier is remarkably large. Possible reactions that may produce the observed αparticles include two-neutron transfer, one-neutron transfer, and direct projectile breakup. Each of these mechanisms results in a distinctive angular correlation between the αparticle and the outgoing neutron(s). A neutron-α-particle coincidence experiment was performed to study two-neutron transfer to unbound states of Bi211. It is shown that approximately 55% of the observed α-particle yield at and beyond the grazing angle is because of this process. This is more than 2.5 times the fraction attributable to single-neutron transfer. The corresponding 2n-transfer cross section is 0.4 ± 0.1 b.
© 2012 American Physical Society
DeYoung, Paul A., Patrick J. Mears, J. J. Kolata, E. F. Aguilera, F. D. Becchetti, Y. Chen, M. Cloughesy et al. "Two-neutron transfer in the He 6+ Bi 209 reaction near the Coulomb barrier." Physical Review C 71, no. 5 (2005): 051601.
Physical Review C - Nuclear Physics