The ${}^3\mathrm{He}$ puzzle, namely, that ${}^3\mathrm{He}$ exhibits anomalously higher kinetic energies per nucleon than tritons ($t$) and $\alpha$ particles in the multifragmentation processes, remains a prominent open issue in the field of heavy-ion collision, as existing interpretations rely primarily on the measured energy spectra and lack constraints from multiple experimental observables. In this work, focusing on the ${}^3\mathrm{He}$ puzzle in comparison to $t$, the differences between $t$ and ${}^3\mathrm{He}$ in in-plane/out-of-plane emission dynamics and emission chronology from the necklike region in the midcentral ${}^{40}\mathrm{Ca}+{}^{40}\mathrm{Ca}$ collisions at 35 MeV/u are experimentally investigated using the two-particle correlation functions. It is found that, compared to $t, {}^3\mathrm{He}$ shows stronger in-plane collective motion, weaker out-of-plane collective motion, and delayed emission time, collectively indicating that, compared to $t, {}^3\mathrm{He}$ tends to be emitted in a less violent collision process or the ${}^3\mathrm{He}$ production is suppressed in a more violent process from an inverse perspective. This work offers novel insights into the ${}^3\mathrm{He}$ puzzle by combining dynamical and chronological observables.

Close

PrevNext

View figure in article

• Collective flow
• Low & intermediate energy heavy-ion reactions
• Nuclear fragmentation
• A ≤ 5