Isotopic Transparency in Central Xe+Sn Collisions at 100 MeV/nucleon

TL;DR

This study introduces a novel method to measure nuclear matter transparency in heavy-ion collisions, revealing high transparency for heavier fragments and unusual transparency for alpha particles at 100 MeV/nucleon.

Contribution

The paper presents a new approach using isotopic yield ratios at different angles to quantify nuclear transparency in central Xe+Sn collisions.

Findings

Moderate transparency for hydrogen isotopes.

High transparency (>50%) for heavier fragments with Z ≥ 3.

Anomalously large transparency observed for alpha particles.

Abstract

A new method, based on comparing isotopic yield ratios measured at forward and sideward polar angles and on cross-bombarding heavy nuclei with different neutron-to-proton ratios, is used to quantify the stopping power of nuclear matter in heavy-ion collisions. For central collisions of isotopically separated $^{124,129}$Xe+$^{112,124}$Sn at 100~MeV/nucleon bombarding energy, measured with the 4$\pi$ multidetector INDRA at GSI, a moderate transparency is deduced for hydrogen isotopes, whereas for heavier fragmentation products with atomic number $Z \ge 3$ a high transparency exceeding 50\% is observed. An anomalously large transparency is found for alpha particles, and possible explanations are presented.