Observing the Ping-pong Modality of Isospin Degree of Freedom in Cluster Emission from Heavy Ion Reactions

TL;DR

This study investigates the isospin dynamics in cluster emissions from heavy ion reactions, revealing a ping-pong modality of N/Z ratios and extending initial system properties to emitted clusters.

Contribution

It provides experimental evidence of the ping-pong modality of isospin in cluster emission and compares transport model calculations to the data.

Findings

Velocity spectra exhibit scaling behavior across heavy clusters.

Yield ratios of t/^3He inversely correlate with N/Z of heavy clusters.

N/Z of residues remains consistent with the initial system value.

Abstract

Two-body correlations of the isotope-resolved light and heavy clusters are measured in $^{86}$Kr+$^{\rm 208}$Pb reactions at 25 MeV/u. The yield and kinetic variables of the $A=3$ isobars, triton and $^3$He, are analyzed in coincidence with the heavy clusters of $7\le A \le 14$ emitted at the earlier chance. While the velocity spectra of both triton and $^3$He exhibit scaling behavior over the type of the heavy clusters, the yield ratios of ${\rm t/^3He}$ correlate reversely to the neutron-to-proton ratio $N/Z$ of the latter, showing the ping-pong modality of the $N/Z$ of emitted clusters. The commonality that the $N/Z$ of the residues keeps the initial system value is extended to the cluster emission in heavy ion reactions. The comparison of transport model calculations to the data is discussed.