Effects of Pauli blocking and in-medium nucleon-nucleon cross sections on the stopping power at low-intermediate energy heavy ion collisions

TL;DR

This study evaluates different Pauli blocking algorithms in nuclear simulations and examines how in-medium nucleon-nucleon cross sections influence the stopping power in low-intermediate energy heavy ion collisions, revealing algorithmic uncertainties and the importance of in-medium effects.

Contribution

It compares three Pauli blocking algorithms' accuracy and investigates the impact of in-medium nucleon-nucleon cross sections on nuclear stopping power in heavy ion collisions.

Findings

Pauli blocking ratios are underestimated by 13-25% in models.

Spurious collisions occur at the nuclear surface due to algorithm defects.

Stopping power varies less than 5% across different algorithms.

Abstract

Three typical algorithms of Pauli blocking in the quantum molecular dynamics type models are investigated in the nuclear matter, the nucleus and the heavy ion collisions. The calculations in nuclear matter show that the blocking ratios obtained with the three algorithms are underestimated 13-25\% compared to the analytical values of blocking ratios. For the finite nucleus, the spurious collisions occur around the surface of the nucleus owing to the defects of Pauli blocking algorithms. In the simulations of heavy ion collisions, the uncertainty of stopping power from different Pauli blocking algorithms is less than 5\%. Furthermore, the in-medium effects of nucleon-nucleon ($NN$) cross sections on the nuclear stopping power are discussed. Our results show that the transport models calculations with free $NN$ cross sections result in the stopping power decreasing with the beam energy at the beam energy less than 300 MeV/u. To increase or decrease the values of stopping power, an enhanced or suppressed model dependent in-medium $NN$ cross section is required.