论文标题
超中心相对论重的沉重碰撞中的自由观众核子作为中子皮肤的探针
Free spectator nucleons in ultracentral relativistic heavy-ion collisions as a probe of neutron skin
论文作者
论文摘要
Besides the yield ratio of free spectator neutrons produced in ultracentral $^{96}$Zr+$^{96}$Zr to $^{96}$Ru+$^{96}$Ru collisions, we propose that the yield ratio $N_n/N_p$ of free spectator neutrons to protons in a single collision system at RHIC and LHC can be a more sensitive probe of the中子皮肤厚度$Δr_ {\ mathrm {np}} $和对称能量的斜率参数$ l $。根据Skyrme-Hartree-fock-Bogolyubov计算获得的碰撞核的质子和中子密度分布来证明这个想法，以及提供观众物质信息的Glauber模型。最终的观众颗粒是由直接发射，最小跨越树算法或Wigner函数方法的聚类产生的，以及双子座对重簇的脱粒。较大的$Δr_ {\ mathrm {np}} $与较大的$ l $值相关联会增加观众物质的异种不对称性，从而导致较大的$ n_n/n_p $，尤其是在超中性碰撞中，在超中性碰撞中，自由核心是自由的，而自由核心则是自由的。我们进一步表明，同位素碰撞系统或同位素碰撞中的$ n_n/n_p $的双重比率有助于取消检测质子的检测效率。研究了核变形和电磁激发的影响，与对$Δr_ {\ mathrm {np}} $的预期灵敏度相比，它们被发现是亚抑制剂。
Besides the yield ratio of free spectator neutrons produced in ultracentral $^{96}$Zr+$^{96}$Zr to $^{96}$Ru+$^{96}$Ru collisions, we propose that the yield ratio $N_n/N_p$ of free spectator neutrons to protons in a single collision system at RHIC and LHC can be a more sensitive probe of the neutron-skin thickness $Δr_{\mathrm{np}}$ and the slope parameter $L$ of the symmetry energy. The idea is demonstrated based on the proton and neutron density distributions of colliding nuclei obtained from Skyrme-Hartree-Fock-Bogolyubov calculations, and a Glauber model that provides information of spectator matter. The final spectator particles are produced from direct emission, clusterization by a minimum spanning tree algorithm or a Wigner function approach, and deexcitation of heavy clusters by GEMINI. A larger $Δr_{\mathrm{np}}$ associated with a larger $L$ value increases the isospin asymmetry of spectator matter and thus leads to a larger $N_n/N_p$, especially in ultracentral collisions where the multiplicity of free nucleons are free from the uncertainties of cluster formation and deexcitation. We have further shown that the double ratio of $N_n/N_p$ in isobaric collision systems or in collisions by isotopes helps to cancel the detecting efficiency for protons. Effects from nuclear deformation and electromagnetic excitation are studied, and they are found to be subdominant compared to the expected sensitivity to $Δr_{\mathrm{np}}$.
