Influence of fast emissions and statistical de-excitation on the isospin transport ratio
Influence of fast emissions and statistical de-excitation on the isospin transport ratio
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DOI：
10.1103/physrevc.102.044607
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发表时间：
2020-10
影响因子：
3.1
通讯作者：
A. Camaiani;S. Piantelli;A. Ono;G. Casini;B. Borderie;R. Bougault;C. Ciampi;J. Dueñas;C. Frosin-C.
中科院分区：
文献类型：
--
作者：
A. Camaiani;S. Piantelli;A. Ono;G. Casini;B. Borderie;R. Bougault;C. Ciampi;J. Dueñas;C. Frosin-C.
同位旋输运比是估算重离子碰撞中中子-质子(n-p)平衡的一种有效方法，被广泛地用来获得核状态方程的松弛-刚性信息。事实上，这样的比率预计将绕过任何引入所选可观测物的线性变换的扰动。特别是，它被认为克服了碰撞过程中形成的初级碎片的动力学或统计性质的发射所产生的贡献。在本文中，我们用反对称分子动力学输运模型，结合不同的统计衰变程序，研究了$35\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}/\mathrm{nucleon}$，上的{Ca}+{Ca}反应在周边和半周边事件中的准投射n-p比($N/Z)。在较高激发能下(当残基接近蒸发吸引线时，在$2\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}/\mathrm{nucleon}$)以上)，初级碎片的统计去激发引入了线性变换，而在较低激发能下，由于出现了一些非线性，产生了一定的影响。对于弹靶相互作用结束后的快速发射，也引入了一种非线性变换。
Isospin transport ratio is a powerful method to estimate the neutron-proton (n-p) equilibration in heavy-ion collisions, and extensively used to obtain information on the asy-stiffness of the nuclear equation of state. In fact such a ratio is expected to bypass any perturbations introducing a linear transformation of the chosen observable. In particular, it is supposed to overcome contributions due to emission, either of dynamical or statistical nature, from the primary fragments formed during the collisions. In this paper we explore the validity of this assumption, looking at the quasiprojectile n-p ratio ($N/Z$) in peripheral and semiperipheral events for $\mathrm{Ca}+\mathrm{Ca}$ reactions at $35\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}/\mathrm{nucleon}$, simulated via the antisymmetrized molecular dynamics transport model, coupled to different statistical decay codes. The statistical de-excitation of the primary fragments introduces a linear transformation at relatively high excitation energies (above $2\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}/\mathrm{nucleon}$) when the residue approaches the evaporation attractor line, while some effect is produced at lower excitation energies due to the occurrence of some nonlinearities. As for fast emissions after the end of the projectile-target interaction it is shown that they introduce a nonlinear transformation too.