Two-nucleon correlation effects in knockout reactions from 12C

TL;DR

This paper investigates two-nucleon knockout reactions from carbon-12, comparing theoretical calculations with experimental data, and finds evidence of enhanced neutron-proton correlations beyond shell-model predictions.

Contribution

It provides a detailed analysis of two-nucleon removal channels from 12C and highlights the role of nucleon correlations in reaction mechanisms.

Findings

Measured np-removal cross sections exceed theoretical predictions.

Reaction mechanism shows enhanced np spatial correlations.

Comparison across multiple energies confirms correlation effects.

Abstract

Reactions that involve the direct and sudden removal of a pair of like or unlike nucleons from a fast projectile beam by a light target nucleus are considered. Specifically, we study the three two-nucleon removal channels from $^{12}${C} that populate final states in the $^{10}${Be}, $^{10}${B} and $^{10}${C} reaction residues. The calculated two-nucleon removal cross sections and the residue momentum distributions are compared with available high energy data at 250, 1050 and 2010 MeV per nucleon, data that are inclusive with respect to the bound final-states of the residues. The measured $np$-removal cross sections only are significantly greater than the values calculated, suggesting that the reaction mechanism observes enhanced $np$ spatial correlations compared to those present in the shell-model wave functions.