Observation of Tensor-Driven High-Momentum Neutrons in ${}^{16}$O via ($p,d$) Reactions and Zero-Degree Deuteron Momentum Spectroscopy

TL;DR

This study demonstrates that zero-degree neutron-pickup reactions in $^{16}$O are highly sensitive to tensor-driven high-momentum neutrons, with experimental results aligning with theoretical models including tensor interactions, thus enabling future investigations in exotic nuclei.

Contribution

The paper provides the first experimental evidence linking high-momentum neutrons to tensor interactions in $^{16}$O via ($p,d$) reactions at zero degrees.

Findings

Positive-parity states show strong high-momentum sensitivity.

Cross-section ratios match tensor interaction predictions.

Results enable studies of exotic nuclei with radioactive beams.

Abstract

The $^{16}\mathrm{O}(p,d)^{15}\mathrm{O}$ reaction has been studied at $0^{\circ}$ using 403-, 604-, 907- and 1209-MeV protons, comparing cross sections populating positive- and negative-parity states in $^{15}\mathrm{O}$. Transitions to positive-parity states exhibit strong sensitivity to high-momentum neutrons, while negative-parity transitions show much smaller effects. The cross-section ratio between positive- and negative-parity states rises sharply with momentum transfer, matching theoretical predictions that include tensor interactions, particularly the peak near $2~\mathrm{fm}^{-1}$ for the $5/2^{+}$ to ground-state ratio. These results highlight $0^{\circ}$ neutron-pickup reactions as a sensitive probe for tensor-driven high-momentum components, paving the way for studies in exotic nuclei via radioactive beams.