High-energy neutron emission and short-range nucleon-nucleon correlations. II. System-size effect
Phys. Rev. C 114, 014631 – Published 23 July, 2026
DOI: https://doi.org/10.1103/nqwp-y33m
Abstract
High-energy neutron emissions from the reactions of on natural C, Cu, and Pb targets at 400 MeV are studied, searching for a possible signature of nucleon-nucleon short-range correlations (SRCs) in the high-energy, high-momentum tails in the neutron spectra. The neutron spectra from the experimental datasets of Y. Iwata et al. [Phys. Rev. C 64, 054609 (2001)] are normalized to the data of R. Madey et al. [Phys. Rev. Lett. 55, 1453 (1985)] above the beam energy per nucleon, using a common reaction of Pb at in both datasets, and compared with those of the Semirelativistic antisymmetrized molecular dynamics (SrAMD) with a three-nucleon collision (3NC) term. In the simulations, each nucleon is boosted with Fermi motion (Fermi-boost), and an empirical high-momentum tail (HMT) in the single-nucleon momentum distribution is incorporated, where HMT is closely related to SRCs. The normalized data of Iwata et al. are reasonably well reproduced, including the high-energy, high-momentum tails at forward angles. However, in overall reproduction, the experimental data with the C target are better reproduced with SrAMD-3NC with HMT in the 3NC process, whereas those with the Cu target are better reproduced without HMT. For the Pb target, the experimental data are well reproduced with SrAMD-3NC both with and without that HMT down to the calculated limit of 1 mb with the available computing power. The dispersion of the three different SrAMD simulations becomes smaller as the system size increases. The essential feature of the prediction of SrAMD for the high-energy, high-momentum tails in the neutron spectra is robust and a possible cause for the origin of the different conclusions on the performance of the SrAMD-3NC with and without HMTs on the different targets is suggested to the quality of the experimental data and this prevents us from drawing a conclusive remark about the necessity of HMT in the single-nucleon momentum distribution in nuclei.
