Report
Collective-flow signatures of bubble nuclei in intermediate-energy projectile fragmentation reactions
| Τίτλος: | Collective-flow signatures of bubble nuclei in intermediate-energy projectile fragmentation reactions |
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| Συγγραφείς: | Ren, Ge, Ma, Chun-Wang, Cao, Xi-Guang, Cheng, Kai-Xuan, Pu, Jie |
| Έτος έκδοσης: | 2026 |
| Συλλογή: | Nuclear Theory Nuclear Experiment |
| Θεματικοί όροι: | Nuclear Theory, Nuclear Experiment |
| Περιγραφή: | Characterized by central density depletion, bubble nuclei represent an important class of exotic nuclear structures. Collective flow in the $^{40}$Ca+$^{9}$Be projectile fragmentation reaction at 140 MeV/u is investigated using the extended quantum molecular dynamics (EQMD) model with a parameter on of the isoscalar monopole excitation strength $\varepsilon$. The projectile $^{40}Ca$ is initialized as a relaxed ten-$α$ cluster configuration exhibiting a bubble-like density distribution. The results reveal that increasing $\varepsilon$ modifies the density distribution and the size of the depleted central region of bubble, producing pronounced changes in fragment yields and collective flow around $\varepsilon\approx0.5$. Below this value, heavy-fragment production plays a significant role, while the directed flow $v_1$ of protons and neutrons remains predominantly negative, indicating preferential emission toward the target side. Above $\varepsilon\approx0.5$, enhanced expansion of the central low-density region suppresses heavy residues and drives $v_1$ toward positive values. In contrast, preformed $α$ clusters show different responses, reflecting their origin in the initial cluster configuration rather than solely in secondary decay. At low excitation, the cluster flow exhibits a pronounced impact-parameter dependence, whereas stronger excitation weakens cluster binding and suppresses directional anisotropy, driving the flow close to zero. The rapidity slopes of the flow coefficients also vary systematically with $\varepsilon$, tracing changes in emission anisotropy during expansion. These findings extend traditional static descriptions by probing the dynamical evolution of exotic structures in heavy-ion reactions and the contrasting collective-flow behavior of preformed clusters and single nucleons constitutes a sensitive dynamical probe of bubble-like structures. 9 pages, 7 figures |
| Τύπος εγγράφου: | Working Paper |
| DOI: | 10.48550/arXiv.2610.19632 |
| Σύνδεσμος πρόσβασης: | https://arxiv.org/abs/2610.19632 |
| Αριθμός Καταχώρησης: | edsarx.2610.19632 |
| Βάση Δεδομένων: | arXiv |
| DOI: | 10.48550/arXiv.2610.19632 |
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