近费米能区重离子碰撞的α关联发射与结团效应

Since the heavy ion physics is an important research field, several heavy ion beam facilities have been constructed all over the world. Cluster effects in nuclei structure and nuclear reaction is fundamental importance in heavy ion physics. The project will study the α correlated emission in heavy ion collisions near Fermi energy, and explore the possible Bose-Einstein condensation (α condensation) in the nuclear matter. First, we will study the influence of four-particle correlations on the phase diagram of nuclear matter, and find the location of the α-condensed phase. Second, in order to understand the trajectories of the colliding nuclear systems in the phase diagram, we will study the energy dissipation and decay mechanism of the hot nuclear system produced in the heavy ion collisions near Fermi energy. Based on the above investigations, we will predict how to produce a nuclear system in the α condensation using the heavy ion collisions. Then, using α correlated emission as a probe, we will study the α condensation in the heavy ion collisions. The transport model is one of the most effective methods to study the heavy ion collisions. We will consider the four-particle correlations in the transport model and provide a theoretical tool for the above investigations of the α correlated emission.

各国相继投入巨资建造放射性束流装置，预示着重离子物理是核物理研究的前沿领域。原子核及核反应中的结团效应是重离子物理的重要研究方向。本项目拟对近费米能区重离子碰撞的结团效应展开研究，探索核子层次可能存在的玻色-爱因斯坦凝聚（α凝聚）。首先，我们将研究四核子关联对核物质相图的影响，寻找α凝聚相的位置。其次，研究近费米能区重离子碰撞的能量耗散与热核衰变机制，了解碰撞中核体系走过的相轨迹。在此基础上，我们将预言能产生α凝聚相的重离子碰撞方案，并以α关联发射作为探针，研究短暂存在的α凝聚相。动力学模型是目前研究重离子碰撞的有效方法之一。我们将在动力学模型中考虑四核子关联，为本项目的α关联发射的研究提供理论工具。

各国相继建造或投入使用放射性束流装置，给重离子物理的理论研究提出了新的要求。原子核及核反应中的结团效应是重离子物理的重要研究方向。本项目对近费米能区重离子碰撞的结团效应展开了研究，探索了核子层次可能存在的玻色-爱因斯坦凝聚（α凝聚）。首先，我们研究了核物质中液相、气相与α凝聚相的相区，基于动力学相轨迹表征了重离子碰撞中核体系在相图中的演化轨迹，预测了有限核体系α凝聚态的临界温度与临界密度。其次，改进了同位旋依赖的量子分子动力学模型，研究了重离子碰撞中氘结团、α结团及中等质量碎片的发射机制。本项目在输运模型发展、α结团效应、原子核相变等方面取得了一系列有价值的学术成果，发表24篇相关的学术论文。本项目的理论研究结果为今后利用重离子碰撞探索α凝聚提供了指引。