Neutron-proton bremsstrahlung from intermediate energy heavy-ion reactions as a probe of the nuclear symmetry energy?

Abstract

Hard photons from neutron-proton bremsstrahlung in intermediate energy heavy-ion reactions are examined as a potential probe of the nuclear symmetry energy within a transport model. Effects of the symmetry energy on the yields and spectra of hard photons are found to be generally smaller than those due to the currently existing uncertainties of both the in-medium nucleon-nucleon cross sections and the photon production probability in the elementary process $pn\to pn\gamma$. Very interestingly, nevertheless, the ratio of hard photon spectra $R_{1/2}(\gamma )$ from two reactions using isotopes of the same element is not only approximately independent of these uncertainties but also quite sensitive to the symmetry energy. For the head-on reactions of ${}^{132}Sn{+}^{124}Sn$ and ${}^{112}Sn{+}^{112}Sn$ at $E_{beam}/A=50$ MeV, for example, the $R_{1/2}(\gamma )$ displays a rise up to 15% when the symmetry energy is reduced by about 20% at $\rho =1.3{\rho }_0$ which is the maximum density reached in these reactions.

Added new results in Fig. 6 and new references [27.28]. Phys. Lett. B in press

References in corpus (6)

• Isospin effects on sub-threshold kaon production at intermediate energies
• Isospin Diffusion in Heavy-Ion Collisions and the Neutron Skin Thickness of Lead
• Probing the Nuclear Symmetry Energy with Heavy-Ion Reactions Induced by Neutron-Rich Nuclei
• The neutron/proton ratio of squeezed-out nucleons and the high density behavior of the nuclear symmetry energy
• In-medium effects on particle production in heavy ion collisions
• Differential cross section for neutron-proton bremsstrahlung

Cited by in corpus (7)

• Imprints of high-momentum nucleons in nuclei on hard photons from heavy-ion collisions around the Fermi Energy
• The interplay of short-range correlations and nuclear symmetry energy in hard photon productions from heavy-ion reactions at Fermi energies
• Decomposition of sensitivity of the symmetry energy observables
• A CsI hodoscope on CSHINE for Bremsstrahlung γ-rays in Heavy Ion Reactions
• Effects of neutron-skin thickness on direct hard photon emission from reactions induced by the neutron-rich projectile ${}^{50}$Ca
• Measurement of the high energy $\gamma$-rays from heavy ion reactions using Čerenkov detector
• The "ab initio" approach to the nuclear equation of state: review and discussion