Investigating α clustering on the surface of Sn 120 via the (p,pα) reaction, and the validity of the factorization approximation

The Sn120(p,pα)Cd116 reaction at 392 MeV is investigated with the distorted wave impulse approximation (DWIA) framework. We show that this reaction is very peripheral, mainly because of the strong absorption of α by the reaction residue Cd116, and the α clustering on the nuclear surface can be probed clearly. We investigate also the validity of the so-called factorization approximation that has frequently been used so far. It is shown that the kinematics of α in the nuclear interior region is significantly affected by the distortion of Cd116, but it has no effect on the reaction observables because of the strong absorption in that region.