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Precise measurement of short-range correlations in nuclei from bremsstrahlung gamma-ray emission in low-energy heavy-ion collisions

Junhuai Xu1,*, Qinglin Niu2, Yuhao Qin1,†, Dawei Si1, Yijie Wang1, Sheng Xiao1, Baiting Tian1, Zhi Qin1, Haojie Zhang1 et al.

Boyuan Zhang1, Dong Guo1, Minxue Fu1, Xiaobao Wei3, Yibo Hao3, Zengxiang Wang3, Tianren Zhuo3, Chunwang Ma3,4, Yuansheng Yang5, Xianglun Wei5, Herun Yang5, Peng Ma5, Limin Duan5, Fangfang Duan5, Kang Wang5, Junbing Ma5, Shiwei Xu5, Zhen Bai5, Guo Yang5, Yanyun Yang5, Mengke Xu6, Kaijie Chen6, Zirui Hao6, Gongtao Fan6, Hongwei Wang6, Chang Xu2,‡, and Zhigang Xiao1,7,§

  • *Contact author: xjh22@mails.tsinghua.edu.cn
  • †Contact author: qinyh18@tsinghua.org.cn
  • ‡Contact author: cxu@nju.edu.cn
  • §Contact author: xiaozg@tsinghua.edu.cn
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Phys. Rev. Research 7, 043174 – Published 17 November, 2025

DOI: https://doi.org/10.1103/jw1p-36pb

Abstract

Atomic nuclei and dense nucleonic matter in neutron stars exhibit short-range correlations (SRCs), where nucleons form temporally correlated pairs in close proximity beyond mean-field approximation. It is essential to make precision measurement of the fraction of SRC since it carries the signature of underlying quark dynamics in nuclear medium. In this article, we present the first high-precision measurement of neutron-proton bremsstrahlung γ-ray emission from the symmetric Sn124+Sn124 reactions at 25 MeV/u. From the observed spectral hardening, the precise SRC fraction in the Sn124 nucleus is extracted to be (20±3)%. This result provides a statistically unambiguous evidence of SRCs and demonstrates that low-energy heavy-ion collisions offer an approach to studying nuclear structure in connection with quark-level dynamics.

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Phys. Rev. Research 7, 043174– Published 17 November, 2025
  • Received 18 June 2025
  • Revised 10 August 2025
  • Accepted 31 October 2025
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