An Approach for the DWBA Calculation of the Two-Nucleon Transfer (p, t) Reaction

Abstract

A new approach of the DWBA calculation for the (p, l) reaction is investigated. The DWBA term is calculated as the two-step non-orthogonality term for Ca(p, t)46Ca(O+, g.s.) reaction at E p =20 MeV and 40 MeV. This, together with the two-step (P-d-l) amplitude calculated by the quasi-particle method, gives the full reaction amplitude in the present scheme. Further, the coherence property of the two-step amplitude is discussed. 6 ),7) who insist that the absolute cross section and the angular distribution of the (p, t) reaction (or ( t, p) reaction) are well described by the one-step DWBA. They analyzed the DWBA term for some cases with a wave function for the triton, and pointed out the importance of improving the form factor for the transferred two neutrons and of using the wave function for the triton. Nowadays, it is still difficult to get a triton wave function, even by means of solving the Faddeev equations or using variational approaches with potentials. It is well known that the wave functions calculated by such methods do not fully reproduce the binding energy and the charge form factor, etc. Thus, the use of the realistic triton wave function for the DWBA calculation in the (p, t) reactions is, strictly speaking, not always appropriate, and, possibly the conclusion obtained by means of such a treatment will be altered in future, especially in the analyses of the polarization phenomena and the unnatural parity transitions. In this paper, we propose a method of calculating the DWBA term accurately and discuss the reaction mechanism. The idea of our approach is to use the mechanism of the cancellation between the non-orthogonality term and the DWBA term. 9 ) In the DWBA calculation of the two-nucleon transfer reaction, we generally encounter the difficulty that the form factor cannot be constructed