SRC Based Model for the Photonuclear Reactions on ${N=Z}$ Light Nuclei

Abstract

The short-ranged correlated nucleonic structures (SRCs) inside nuclei have been confirmed using a diverse set of energetic probes like photons, pions, $e^{-}$, and hadrons. In $N=Z$ light nuclei, the strong $NN$ interaction between neutrons ($n$) and protons ($p$) occupying similar orbitals is not restricted by Pauli’s Principle and will be enhanced by the presence of opposite surface charge distributions in $n$ and $p$. Additionally, the tensor nature of $NN$ interaction would lead to the formation of quasi-deuterons or short-ranged $np$ correlated structures in nuclei as observed in numerous experimental works. By scaling the well-known photonuclear cross-section formulae for free deuteron with an appropriate $n$–$p$ separation energy and $r_{0t}$ parameter, the quasi-deuteron or $\sigma(\gamma,np)$ cross-sections for some of $N=Z$ light nuclei are computed. Using the Gunn–Irving approach for $(\gamma,N)$ channel, the total photonuclear cross-sections $(\sigma_{\text{tot}})$ are evaluated. A significant fraction of $\sigma_{\text{tot}}$ in the GDR region may be accounted for by the $\sigma(\gamma,N)$ contribution, which decreases quickly for higher $E_{\gamma}$ values. In contrast, the $(\gamma,np)$ contribution dominates for $E_{\gamma}>50$ MeV. The current research proposes an alternative and viable formalism for calculating the photonuclear cross-sections for the $N=Z$ light nuclei.