近些年来，中等能量重离子碰撞中新核素的产生受到广泛关注。原子核多重碎裂是产生新核素的重要反应机制。4π探测器问世以后，多重碎裂的一般特征已经被广泛研究。将来进一步的发展与许多观测量以及多重碎裂事件相关性的研究有关。原子核多重碎裂是产生稀有同位素的有效方式，在原子核物理中有着重要的作用。次级束装置的建成使得通过具有丰中子或丰质子的放射性核束流研究同位旋相关的重离子碰撞动力学成为可能。丰中子原子核参与的反应可以为同位旋相关的核状态方程提供重要的信息。同时，丰中子核素的合成也有助于对原子核结构特征进行深入的研究。利用放射性束流，可以研究不同能量、不同弹核靶核组合的原子核反应中远离β稳定线原子核的性质以及同位旋的自由度。核素图滴线附近的区域受到了广泛的关注，这对于阐释核结构随着中子质子比增加发生的变化，以及研究核合成的途径都很重要。因此研究丰中子同位素和滴线附近核素的产生很有意义。本文运用同位旋相关的量子分子动力学模型和统计衰变模型GEMINI，描述中等能量重离子碰撞反应的微观反应过程，研究丰中子核素以及滴线附近核素的产生。本文的主要研究内容如下：一、研究了不同入射能量下112Sn+112Sn和124Sn+124Sn 反应不同碎片的产生截面。计算了He、O和Ca的同位素的产生截面，并对48Ca和54Ca的产生截面做了重点讨论与研究。研究发现，丰中子同位素的种类与产生截面依赖于体系的同位旋和入射能量。能量在30-150 MeV/nucleon 范围内，48Ca和54Ca 在丰中子体系中产生截面更大。二、研究了入射能量为60、100、140 MeV/nucleon时64Ni+181Ta反应中核素的产生截面，并在能量为140 MeV/nucleon时与58Ni+181Ta反应产生的核素做了比较。研究发现，Na、Mg、Al、Si、P等元素的接近中子滴线的同位素的产生截面总体上随能量的增加而减小，而64Ni+181Ta反应中产生的中子滴线附近的同位素比58Ni+181Ta反应产生的多。本文的主要创新点如下：（1）改进了量子分子动力学模型，采用了新的势参数；（2）给出了丰中子同位素的产生截面与体系同位旋与入射能量的关系；（3）得到了滴线附近的新核素的产生截面。

The nuclear multifragmentation is an important reaction mechanism in heavy ioncollisions. General characteristics of the multifragmentation reaction have been observedsince the advent of powerful 4π detectors. It appears that further improvements are re-lated to the study of many observables and the correlations in the multifragment events.Nuclear fragmentation is a well-established technique to achieve rare isotope beams, andplays an important role in nuclear physics. Much progress has been made in the pro-duction of neutron-rich nuclides in recent years. With the establishment of secondarybeam facilities, radioactive beams of nuclei with large neutron or proton excess have pro-vided a terrific opportunity to investigate the isospin-dependence of heavy ion collisiondynamics. Reactions induced by neutron-rich nuclei provide crucial information on theisospin dependence of the nuclear equation of state. Moreover, the synthesis and studyof neutron-rich nuclides can give much information about the properties of the nuclearstructure. Using a radioactive nuclear beam, one can study the properties of nuclei veryfar from the β stability line and isospin degrees of freedom in nuclear reactions at wideenergy ranges for different projectile-target combinations. Investigation of the nuclearlandscape close to the neutron-drip line is widely concerned, for the sake of explain-ing the evolution of nuclear structure with increasing neutron-to-proton ratio (N/Z) andunderstanding vital nucleosynthesis pathways. Therefore it is important to investigatethe production of neutron-rich isotopes and nuclei close to the drip line. In this thesis,heavy-ion collisions at intermediate energies are studied based on the isospin-dependentquantum molecular dynamics model along with the GEMINI model.The production cross sections of different fragments for reactions of 112Sn+112Snand 124Sn+124Sn at different beam energies are investigated. The production cross sec-tions of He, O and Ca are calculated. The species and production cross sections ofneutron-rich isotopes are generally dependent on the isospin of the system and the in-cident energies. The isotopes 48Ca and 54Ca are more productive for the neutron-richsystem at 30 to 150 MeV/nucleon.The production cross sections of nuclei for the reaction of 64Ni+181Ta at 60,100and 140 MeV/nucleon are studied, and the data at 140 MeV/nucleon are compared withthose for the reaction of 58Ni+181Ta. The production cross sections of nuclei such as theisotopes of Na, Mg, Al, Si and P generally decrease with the energy. The production crosssections of isotopes close to the neutron drip line are more productive for the neutron-richsystem 64Ni+181Ta.