$P_{\mathrm{tot}}$门和速度门对中能重离子碰撞中轻粒子动量关联的影响
Effects of $P_{\mathrm{tot}}$ gates and velocity gates on light-particle momentum correlation in intermediate-energy heavy-ion collisions
摘要：
在由$Lednick\acute{y}$和$Lyuboshitz$分析方法补充的同位旋相关量子分子动力学模型框架内，计算了不同碰撞参数和束流能量下，$^{197}$ Au + $^{197}$ Au碰撞发射的轻粒子$\left(n, p, d, t\right)$在小相对动量下的动量关联函数.我们首先确保我们的模型能够在0.4 $A$ GeV到1.5 $A$ GeV的宽能量范围内再现质子-质子动量相关的FOPI数据。然后，我们通过不同光粒子之间的发射时间和动量相关性探索更多的物理见解。重点讨论了不同轻粒子对动量、碰撞参数和介质中核子-核子碰撞截面的影响。由于末态相互作用的存在，两个氘核和两个Triton的关联函数都是反关联的，当粒子对的总动量较大时，关联函数受介质中核子-核子截面的影响，而当粒子对的总动量较小时，关联函数不受介质中核子-核子截面的影响.此外，通过拟合动量关联函数，提取了碰撞参数和介质中核子-核子截面对发射源半径的依赖关系。结果表明，核子-核子碰撞截面因子$\left(η\right)$或碰撞参数$\left(b\right)$越小，动量关联函数对总对动量的门控越强.用速度门关联函数研究了不同粒子（$np, pd, pt, $和$dt$）的关联，结果表明，在相对动量较小的区域，较重粒子$\left(deuteron/triton\right)$的平均发射时间早于质子。
英文摘要：
Momentum correlation functions at small relative momenta are calculated for light particles $\left(n, p, d, t\right)$ emitted from $^{197}$Au + $^{197}$Au collisions at different impact parameters and beam energies within the framework of the isospin-dependent quantum molecular dynamics model complemented by the $Lednick\acute{y}$ and $Lyuboshitz$ analytical method. We first make sure our model is able to reproduce the FOPI data of proton-proton momentum correlation in a wide energy range from 0.4$A$ GeV to 1.5$A$ GeV. Then we explore more physics insights through the emission times and momentum correlations among different light particles. The specific emphasize is the effects of total pair momentum among different light particles, impact parameters and in-medium nucleon-nucleon cross section. Both two-deuteron and two-triton correlation functions are anti-correlation due to the final state interaction, and they are affected by in-medium nucleon-nucleon cross section for the higher total momentum of the particle pairs, but not for the lower ones. In addition, impact parameter and in-medium nucleon-nucleon cross section dependences of the emission source radii are extracted by fitting the momentum correlation functions. The results indicate that momentum correlation functions gating with total pair momentum is stronger for the smaller in-medium nucleon-nucleon cross section factor $\left(η\right)$ or impact parameter $\left(b\right)$. Non-identical particle correlations ($np, pd, pt, $ and $dt$) are also investigated by the velocity-gated correlation functions which can give information of the particles' emission sequence, and the result indicates that heavier ones $\left(deuteron/triton\right)$ are, one the average, emitted earlier than protons, in the small relative momentum region.
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