分类： 物理学 >> 核物理学 提交时间： 2023-06-20
摘要： The ratio of the number of emitted pions from the target side to that from the projectile side at target rapiditywithin the reaction plane is investigated for the study of the pion dynamics with an isospin-dependent quantummolecular dynamic model. The results show that high-energy pions are emitted preferentially towards the targetside and, therefore, they are freezed out at the early stage of the collision. By contrast, low-energy pionsare emitted predominantly in the opposite direction, which means that they are emitted in later stage. Thisarguement is based on the shadowing effect caused by the interaction of pions with the spectator matter inperipheral collisions at target or projectile rapidities. This phenomenon disappears in the central collision or atmidrapidity due to the weaker shadowing effect. The calculated ratios are also compared with the experimentaldata.
分类： 物理学 >> 核物理学 提交时间： 2023-06-20
摘要： The proton-proton momentum correlation function (Cpp) from di#11;erent rapidity regions are systematically investigated for the Au + Au collisions at di#11;erent impact parameters and di#11;erentenergies from 400A MeV to 1500A MeV in the framework of the isospin-dependent quantum molecular dynamics model (IQMD) complemented by the Lednick #19; y and Lyuboshitz analytical method.In particular, in-medium nucleon-nucleon cross section (NNCS) dependence of the correlation function is brought into focus, while the impact parameter and energy dependence of the momentumcorrelation function are also explored. The sizes of the emission source are extracted by #12;tting themomentum correlation functions using the Gaussian source method. We #12;nd that the in-mediumnucleon-nucleon cross section obviously in uence the proton-proton momentum correlation functionwhich is from the whole rapidity or projectile/target rapidity region at smaller impact parameters,but there is no e#11;ect on the mid-rapidity proton-proton momentum correlation function, whichindicates that the emission mechanism di#11;ers between projectile/target rapidity and mid-rapidityprotons.
分类： 物理学 >> 核物理学 提交时间： 2023-06-20
摘要： The number of nucleon (NN) scaling of the directed ow v1 and elliptic ow (v2) as well as thenuclear modi#12;cation factor (Rcp) are tested for light nuclei which are produced in 0.4A GeVAu +Au collisions at di#11;erent impact parameters with two di#11;erent in-medium nucleon-nucleon cross sections in aframework of an isospin-dependent quantum molecular dynamics (IQMD) model. In that energy domain,the emission of light nuclei can be well described by the squeeze-out phenonomenon. The results show anice NN scaling behavior for ow parameters v1, v2 and Rcp. These results demonstrate that the nucleoncoalescence mechanism is responsible for nucleon-number scaling of above physical observables in squeezeout region in heavy-ion collisions at intermediate energy.
分类： 物理学 >> 核物理学 提交时间： 2023-06-20
摘要： Two-nucleon momentum correlation functions are investigated for different single thermal sourcesat given initial temperature (T ) and density (). To this end, the evolutions of various singleexcited nuclei at T = 1 20 MeV and = 0.2 - 1.2 0 are simulated using the thermal isospindependent quantum molecular dynamics (T hIQMD) model. Momentum correlation functions ofidentical proton-pairs (Cpp(q)) or neutron-pairs (Cnn(q)) at small relative momenta are calculatedby Lednick y and Lyuboshitz analytical method. The results illustrate that Cpp(q) and Cnn(q) keepsensitivities to the source size (A) at lower T or higher , but almost not at higher T or lower . Andthe sensitivities become stronger for smaller source. Moreover, the T , and A dependencies of theGaussian source radii are also extracted by fitting the two-proton momentum correlation functions,and the results are consistent with the above conclusions.
分类： 物理学 >> 核物理学 提交时间： 2023-06-20
摘要： Momentum correlation functions of light (anti)nuclei formed by the coalescence mechanism of (anti)nucleons are calculated in several relativistic heavy-ion collision systems, namely B +B, O +O, Ca +Ca as well as Au +Au, at di#11;erent centralities at center of mass energy 39 GeV within the framework of A Multi-Phase Transport (AMPT) model complemented by the Lednick#19; y and Lyuboshitz analytical method. Momentum correlation functions for identical or nonidentical light (anti)nuclei are constructed in the above collision systems at so high collision energy. The results suggest that emission of light (anti)nuclei occurs from a source of smaller spacetime extent in more peripheral collisions. The e#11;ect of system-size on the momentum correlation functions of identical or nonidentical light (anti)nuclei is also explored in several central collisions. The results indicate that the emission source-size of light (anti)nuclei pairs deduced from their momentum correlation functions and system-size is self-consistent. Momentum correlation functions of nonidentical light nuclei pairs gated on velocity are applied to infer the average emission sequence of them. The results indicate that protons are emitted in average on a similar time scale with neutrons but earlier than deuterons or tritons in the small relative momentum region. In addition, larger interval of the average emission order among them is observed by large centrality and smaller system collisions.
点击量
通过
点击量
下载量
评论
