Systematic reduction of the proton-removal cross section in neutron-rich medium-mass nuclei

TL;DR

This study systematically measures neutron- and proton-removal cross sections in medium-mass neutron-rich nuclei at high energies, revealing a significant reduction in proton-removal cross sections due to short-range correlations not accounted for in traditional models.

Contribution

The paper provides the first systematic measurement of both neutron- and proton-removal cross sections in this mass region and highlights the role of short-range correlations in proton knockout processes.

Findings

Neutron-removal cross sections align with knock-out models including initial- and final-state interactions.

Proton-removal cross sections are significantly smaller than predictions, indicating additional effects.

Short-range correlations in neutron-proton pairs explain the reduced proton-removal cross sections.

Abstract

Single neutron- and proton-removal cross sections have been systematically measured for 72 medium-mass neutron-rich nuclei around Z=50 and energies around 900A MeV using the FRagment Separator (FRS) at GSI. Neutron-removal cross sections are described by considering the knock-out process together with initial- and final-state interactions. Proton-removal cross sections are, however, significantly smaller than predicted by the same calculations. The observed difference can be explained as due to the knockout of short-correlated protons in neutron-proton dominating pairs.