Temperature and density effects on the two-nucleon momentum correlation function from excited single nuclei

TL;DR

This study investigates how temperature and density influence two-nucleon momentum correlation functions in excited nuclei, revealing sensitivities to source size and conditions through simulations and analytical methods.

Contribution

It introduces a detailed analysis of temperature and density effects on nucleon correlations using the ThIQMD model and analytical correlation functions, highlighting conditions affecting sensitivity.

Findings

Correlation functions are sensitive to source size at low T or high density.

Sensitivity of correlation functions increases for smaller sources.

Gaussian source radii depend on T, ρ, and A, consistent with correlation function behavior.

Abstract

Two-nucleon momentum correlation functions are investigated for different single thermal sources at given initial temperature $(T)$ and density $(\rho)$. To this end, the space-time evolutions of various single excited nuclei at $T$ $= 1 - 20$ $MeV$ and $\rho$ = 0.2 - 1.2 $\rho_0$ are simulated by using the thermal isospin-dependent quantum molecular dynamics $(ThIQMD)$ model. Momentum correlation functions of identical proton-pairs ($C_{pp}(q)$) or neutron-pairs ($C_{nn}(q)$) at small relative momenta are calculated by $Lednick\acute{y}$ and $Lyuboshitz$ analytical method. The results illustrate that $C_{pp}(q)$ and $C_{nn}(q)$ are sensitive to the source size ($A$) at lower $T$ or higher $\rho$, but almost not at higher $T$ or lower $\rho$. And the sensitivities become stronger for smaller source. Moreover, the $T$, $\rho$ and $A$ dependencies of the Gaussian source radii are also extracted by fitting the two-proton momentum correlation functions, and the results are consistent with the above conclusions.