Investigation of the short-range correlation and its induced high-momentum tail by photon emission from intermediate energy heavy-ion reactions

TL;DR

This study investigates how short-range correlations (SRC) and the resulting high-momentum tail (HMT) in neutron-rich nuclei influence hard-photon emission in intermediate-energy heavy-ion reactions. Using the isospin-dependent BUU transport framework with SBKD/MDI mean fields and in-medium NN cross sections, the authors compare nucleon momentum distributions with and without HMT (FFG vs HMT) and compute proton-neutron bremsstrahlung photon production perturbatively, including two cross-section formalisms. They find that HMT enhances high-energy photon production, with a stronger effect at lower beam energies and in heavier systems, and demonstrate that the ratio $R_p$ of double-differential photon production between two beam energies is a sensitive, reduced-uncertainty probe of HMT (up to about $10\%$), differentiating HMT from FFG and showing dependence on the chosen mean-field potential. The results suggest that $R_p$ can be used experimentally to constrain SRC-induced HMT in neutron-rich nuclei, contributing to a better understanding of isospin-dependent momentum distributions and their impact on nuclear dynamics.

Abstract

The effect of high-momentum tail (HMT) in nucleon momentum distribution of neutron-rich nuclei has been investigated by employing proton-neutron bremsstrahlung photons in the reactions of $^{124}$Sn +$ ^{124}$Sn, $^{112}$Sn + $^{112}$Sn and $^{197}$Au + $^{197}$Au at intermediate energies based on the IBUU transport model. With the time evolution of photon multiplicity and the double differential probability of photon production, we show the emission of bremsstrahlung photons is sensitive to the high-momentum component in nucleon momentum distribution of neutron-rich nuclei, and the HMT can lead to an obvious increase of hard photon production from proton-neutron bremsstrahlung collisions. Finally, the ratio of double differential photon production probability is examined as possible probe of the HMT in nucleon momentum distribution of neutron-rich nuclei.

Figures (7)

• Figure 1: Beam energy dependence of the inclusive photon production cross sections in ${}^{12}$C + ${}^{12}$C collisions. The cross center symbols are the FFG case, the open symbols are the HMT case and the solid symbols are from experimental data Grosse(The circles are for energy region 50 MeV $\leq E_{\gamma} \leq$ 100 MeV and squares for 100 MeV $\leq E_{\gamma} \leq$ 150 MeV).
• Figure 2: Time evolution of multiplicity of hard photons with energy 50 MeV $\leq E_{\gamma} \leq$ 215 MeV in ${}^{124}$Sn + ${}^{124}$Sn central reaction in the FFG and HMT cases, respectively.
• Figure 3: Time evolution of the photon multiplicity in the ${}^{124}$Sn + ${}^{124}$Sn collisions at a beam energy of 50 MeV/nucleon with different impact parameter settings in both the FFG and HMT cases.
• Figure 4: The double differential probabilities of photon production in ${}^{124}$Sn + ${}^{124}$Sn central reactions at beam energies of 50 MeV/nucleon and 140 MeV/nucleon, respectively.
• Figure 5: The double differential probability of bremsstrahlung photons in ${}^{124}$Sn + ${}^{124}$Sn central reactions at a beam energy of 140 MeV/nucleon using SKBD and MDI interactions, respectively.