Reaction mechanisms of pair transfer

TL;DR

This paper explores the detailed mechanisms of two-nucleon transfer reactions in nuclear physics, defining overlap functions, transformation coefficients, and analyzing simultaneous and sequential transfer processes with shell-model calculations.

Contribution

It introduces a comprehensive framework for describing pair transfer mechanisms, including coordinate system transformations and the interplay of different transfer pathways.

Findings

Demonstrates the use of shell-model overlap functions for specific reactions.

Shows the interference effects between simultaneous and sequential transfer amplitudes.

Highlights the importance of prior-post coupling combinations in avoiding non-orthogonality.

Abstract

The mechanisms of nuclear transfer reactions are described for the transfer of two nucleons from one nucleus to another. Two-nucleon overlap functions are defined in various coordinate systems, and their transformation coefficients given between coordinate systems. Post and prior couplings are defined for sequential transfer mechanisms, and it is demonstrated that the combination of `prior-post' couplings avoids non-orthogonality terms, but does not avoid couplings that do not have good zero-range approximations. The simultaneous and sequential mechanisms are demonstrated for the $^{124}$Sn(p,t)$^{122}$Sn reaction at 25 MeV using shell-model overlap functions. The interference between the various simultaneous and sequential amplitudes is shown.