Proton induced deuteron knockout reaction as a probe of an isoscalar proton-neutron pair in nuclei

TL;DR

This study investigates the potential of proton-induced deuteron knockout reactions to serve as a probe for isoscalar proton-neutron pairs in nuclei, establishing a clear link between pairing strength and reaction cross sections.

Contribution

It demonstrates a direct correlation between the $pn$ pairing strength in theoretical models and the triple differential cross section in ($p,pd$) reactions, highlighting the reaction's potential as a probe.

Findings

Clear $V_0$ dependence of TDX observed

Nuclear distortion enhances $V_0$ dependence

($p,pd$) reaction is promising for probing $pn$ pairs

Abstract

The isoscalar $pn$ pair is expected to emerge in nuclei having the similar proton and neutron numbers but there is no clear experimental evidence for it. We aim to clarify the correspondence between the $pn$ pairing strength in many-body calculation and the triple differential cross section (TDX) of proton-induced deuteron knockout ($p,pd$) reaction on $^{16}$O. The radial wave function of the isoscalar $pn$ pair with respect to the center of $^{16}$O is calculated with the energy density functional (EDF) approach and is implemented in the distorted wave impulse approximation (DWIA) framework. The $pn$ pairing strength $V_0$ in the EDF calculation is varied and the corresponding change in the TDX is investigated. A clear $V_0$ dependence of the TDX is found for the $^{16}$O($p,pd$)$^{14}$N($1_2^+$) at $101.3$ MeV. The nuclear distortion is found to make the $V_0$ dependence stronger. Because of the clear $V_0$-TDX correspondence, the ($p,pd$) reaction will be a promising probe for the isoscalar $pn$ pair in nuclei. For quantitative discussion, further modification of the description of the reaction process will be necessary.