Sequential Heavy Ion Double Charge Exchange Reactions and the Link to Double $\beta$-decay

TL;DR

This paper models heavy ion double charge exchange reactions as sequential meson-exchange processes, providing quantum mechanical calculations that relate these reactions to double beta decay, with applications to calcium-40 reactions at 15 AMeV.

Contribution

It introduces a quantum mechanical framework for describing DSCE reactions via a double single charge exchange mechanism, linking these reactions to double beta decay through nuclear matrix element analysis.

Findings

Quantum mechanical calculations match experimental data well.

Intermediate propagator approximation simplifies complex calculations.

Comparison of nuclear matrix elements links DSCE reactions to double beta decay.

Abstract

Heavy ion double charge exchange reactions are described by sequential meson-exchange, corresponding to a double single charge exchange (DSCE) reaction mechanism. The theoretical formulation is discussed. The fully quantum mechanical distorted wave 2-step calculations are shown to be reproduced very well by approximating the intermediate propagator by its pole part. The role of ion-ion elastic interactions is discussed. As a first application, calculations are performed for the reaction $^{40}$Ca $(^{18}$O $,^{18}$Ne $)^{40}$Ar at 15 AMeV. Results are compared to the data measured at LNS by the NUMEN Collaboration. The common aspects of DSCE reactions and double $\beta$- decay are discussed by a detailed comparison of the respective nuclear matrix elements (NME).