In-medium effects around the Fermi energy

O Lopez,G Lehaut,D Durand

doi:10.1051/epjconf/20158800006

Abstract

We study nuclear stopping in central collisions for heavy-ion induced reactions in the Fermi energy domain (15-100 AMeV). Using the large dataset provided by the 4π array INDRA, we determine that stopping can be directly related to the transport properties in the nuclear medium. By looking specifically at protons, we present a comprehensive body of experimental results concerning the mean free path, the nucleon-nucleon cross-section and in-medium effects in nuclear matter.

Highlights

Transport properties in nuclear matter contribute to the determination of the equation of state via the underlying in-medium properties of the nuclear interaction [1]- [8] as well as in the description of the supernova core collapse and the subsequent formation of a neutron star [9]
This depicts the fact that the Pauli principle suppresses to a large extent NN collisions at low incident energy and increases the mean free path around the Fermi energy [11]
If we focus on the high energy domain, i.e. above the Fermi energy, we note a continuous decrease of λNN, whatever the system size, toward an asymptotic value corresponding to λNN = 4.5 ± 1 f m above 100 A MeV

Summary

Introduction

Transport properties in nuclear matter contribute to the determination of the equation of state via the underlying in-medium properties of the nuclear interaction [1]- [8] as well as in the description of the supernova core collapse and the subsequent formation of a neutron star [9]. Numerous theoretical approaches show that the cross section has to be properly renormalized in order to account for the effective NN collision rate in HIC [11, 12, 14] as depicted in theoretical works [15,16,17]. These latter show that the nucleon mean free path is large for Einc/A ≤ 100 MeV, and decreases toward a saturation value λNN = 4 − 5 f m around Einc/A ≈ 100 MeV [17].

IN DRA dataset

Event and particle selections

Stopping ratio and NN collisions

In-medium effects

Conclusions