Isospin transport in 84Kr+112,124Sn reactions at Fermi energies

TL;DR

This study investigates isospin transport phenomena in heavy ion collisions at Fermi energies, revealing isospin diffusion and drift effects through detailed measurements of fragment isotopic compositions.

Contribution

It provides experimental evidence of isospin diffusion and drift in 84Kr+Sn reactions at Fermi energies using advanced isotopic resolution detectors.

Findings

Higher <N>/Z in n-rich target reactions indicating isospin diffusion.

Increase in <N>/Z of light fragments from QuasiProjectile to neck zone showing isospin drift.

Detection of isospin transport phenomena driven by density and isospin gradients.

Abstract

Isospin transport phenomena in dissipative heavy ion collisions have been investigated at Fermi energies with a beam of 84Kr at 35AMeV. A comparison of the <N>/Z of light and medium products forward-emitted in the centre of mass frame when the beam impinges on a n-poor 112Sn and a n-rich 124Sn targets is presented. Data were collected by means of a three-layer telescope with very good performances in terms of mass identification (full isotopic resolution up to Z about 20 for ions punching through the first detector layer) built by the FAZIA Collaboration and located just beyond the grazing angle for both reactions. The <N>/Z of the decay products emitted when the n-rich target is used is always higher than that associated to the n-poor one. Since the detector was able to measure only fragments coming from the QuasiProjectile decay and/or neck emission, the observed behaviour can be ascribed to the isospin diffusion, driven by the isospin gradient between QuasiProjectile and QuasiTarget. Moreover, for light fragments the <N>/Z as a function of the lab velocity of the fragment increases when we move from the QuasiProjectile velocity to the centre of mass (neck zone). This effect can be interpreted as an evidence of isospin drift driven by the density gradient between the QuasiProjectile zone (at normal density) and the more diluted neck zone.