对核物质状态方程的研究将有助于人们更好地了解原子核的性质以及宇宙和星体的演化过程等基本问题。重离子碰撞能产生高温高密核物质,利用输运模型的模拟结合相关实验数据的比较是研究核物质状态方程最常用方法之一。本文利用深度学习...对核物质状态方程的研究将有助于人们更好地了解原子核的性质以及宇宙和星体的演化过程等基本问题。重离子碰撞能产生高温高密核物质,利用输运模型的模拟结合相关实验数据的比较是研究核物质状态方程最常用方法之一。本文利用深度学习中的卷积神经元网络(CNN)方法对不同核物质状态方程给出的末态质子横动量和快度分布进行学习,使神经元网络具有从末态粒子信息来判断核物质状态方程软硬的能力。利用预测差异分析方法(Prediction Different Analysis),可以找到横动量和快度分布中对状态方程最敏感的区域。此外,还测试了一种基于决策树的梯度提升算法(LightGBM),发现得到的准确度和CNN方法类似。展开更多
The equation of state of symmetric nuclear matter is studied with an equivalent mass model.The equivalent mass of a nucleon has been expanded to order 4 in density.We first determine the first-order expansion coeffici...The equation of state of symmetric nuclear matter is studied with an equivalent mass model.The equivalent mass of a nucleon has been expanded to order 4 in density.We first determine the first-order expansion coefficient in the quantum hadron dynamics,then calculate the coefficients of the second to fourth order for the given binding energy and incompressibility at the normal nuclear saturation density.It is found that there appears a density isomeric state if the incompressibility is smaller than a critical value.The model dependence of the conclusion has also been checked by varying the first-order coefficient.展开更多
文摘对核物质状态方程的研究将有助于人们更好地了解原子核的性质以及宇宙和星体的演化过程等基本问题。重离子碰撞能产生高温高密核物质,利用输运模型的模拟结合相关实验数据的比较是研究核物质状态方程最常用方法之一。本文利用深度学习中的卷积神经元网络(CNN)方法对不同核物质状态方程给出的末态质子横动量和快度分布进行学习,使神经元网络具有从末态粒子信息来判断核物质状态方程软硬的能力。利用预测差异分析方法(Prediction Different Analysis),可以找到横动量和快度分布中对状态方程最敏感的区域。此外,还测试了一种基于决策树的梯度提升算法(LightGBM),发现得到的准确度和CNN方法类似。
基金Supported by National Natural Science Foundation of China(NSFC) Projects (Nos.11135011 and 11045006)the key project from Chinese Academy of Sciences(No.12A0A0012)
文摘The equation of state of symmetric nuclear matter is studied with an equivalent mass model.The equivalent mass of a nucleon has been expanded to order 4 in density.We first determine the first-order expansion coefficient in the quantum hadron dynamics,then calculate the coefficients of the second to fourth order for the given binding energy and incompressibility at the normal nuclear saturation density.It is found that there appears a density isomeric state if the incompressibility is smaller than a critical value.The model dependence of the conclusion has also been checked by varying the first-order coefficient.
