Observing the ping-pong modality of the isospin degree of freedom in cluster emission from heavy-ion reactions

Abstract

Thermodynamic and chemical two-body correlations of the isotope-resolved clusters are measured in $^{86}\mathrm{Kr}+^{208}\mathrm{Pb}\phantom{\rule{4pt}{0ex}}$reactions at 25 MeV/u. The yield and kinetic variables of the $A=3$ isobars are analyzed in coincidence with the intermediate mass fragments of $6\ensuremath{\le}A\ensuremath{\le}11$. While the velocity spectra of both $t$ and $^{3}\mathrm{He}$ exhibit scaling behavior over the type of the intermediate mass fragments, the yield ratios of $t/^{3}\mathrm{He}$ correlate reversely to the neutron-to-proton ratio $N/Z$ of the latter, showing the ping-pong modality of the $N/Z$ of the emitted particles. 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 to transport model calculations to the data is discussed.