Strong two-step contributions in direct allowed two-nucleon transfers

The h/sub 9/2/g/sub 9/2/ multiplet in /sup 210/Bi was populated by /sup 208/Pb(..cap alpha.., d) in experiments at 33 and 48 MeV. The strong favoring of the five unnatural-parity states of the multiplet disagrees with one-step transfer distorted-wave Born-approximation predictions. Coupled-reaction-channels calculations explain this effect as interference of direct np transfer and successive stripping amplitudes of comparable magnitude. This holds for weak (low-spin) and strong (high-spin) members of the multiplet.