Even if qgp is formed , it can just exist for a very short period of time and then decays into final state hadrons at the end of the expansion and the cooling of the system . the initial state information may be damaged by the final state interactions during the evolution process 在相对论性核?核碰撞中，即使qgp已形成了，也只是在碰撞过程的极短瞬间存在，随着系统的膨胀与冷却，它很快就演化为实验观测到的各种末态粒子，最初存在的信息也可能在演化过程中由于各种末态相互作用而变得不清晰了。
Therefore it is necessary to study the contribution of hadron environment to the suppression . many works have studied j / suppression in hadron environment with glauber model . but the combination of nucleus absorption and comover mechanism in hadron environment can not explain the abnormal suppression of j / production in pb - pb collision yet 但是强子环境中的核吸收和同行粒子对j w的相互作用机制结合起来仍不能解释pbpb碰撞过程中j w的反常压低，也就是说需要引入新的机制，这可能预示着夸克一胶子等离子体的形成。
Therefore j / v is the border guard of perturbative quark and gluon and non - perturbative hadron . j / v production can be divided into two phases : cc pairs are produced from initial short - range parton scattering in nucleus - nucleus collision , then the produced cc pairs proceed to evolving into physical bound state 基于对强子?强子碰撞中j产生的研究，目前人们认为j的产生可分成两个阶段：入射强子和靶强子先通过部分子过程产生cc对，然后cc对再演化为物理的j束缚态。
The knowledge of these initial collision is crucial for any theoretical treat - ment of a possible parton - hadron phase transition , the detection of which being the ultimate aim of all the efforts of co1liding heavy ions at very high energies . the parton model allows to calculate inclusive cross sections as a convolution of any elementary cross section with parton distribution functions , assuming that factorization works . the disadvantage is that tlle first interaction is coilsidered quite differently from the subsequent ones in case of multiple scattering 其它的弦模型在计算几率时，忽略了入射能量在pomeron之间的分配，破坏了能量守恒，而且把pomeron作为全同粒子处理，即pomeron之间是不可区分的；然而在处理粒子产生时，这些模型虽然考虑了能量守恒，但是第一个pomeron的粒子产生与其它的pomeron很不一样? ? pomeron在粒子产生时不是全同的。
The reflector can increase the neutron flux obviously and the main processes of the neutron yield in reflector are spallation reaction induced by energetic hadrons and ( n , 2n ) reaction . when the moderator height is equal to the distance between the upper part and the lower part of the split target , the total neutron flux of the split target will be higher by 20 . 1 % than that of the integral one . secondly , the high - energy neutron escaping from the target will enter into the moderator and be slowed down 得到经水慢化器慢化后，中子通量在慢化器厚度与高度方向上的分布；比较了水与液态氢的慢化能力以及中子在水、液态氢、液态甲烷这三种慢化器慢化后的能谱；在csns的靶站设计中，引出慢中子的导管不完全位于慢化器中子引出面的法线方向上，因此进一步计算了中子通量角分布。
In quantum chromodynamics ( qcd ) , vacuum is not trivial , that is , vacuum carry quantum numbers . such a behavior is embodied by non - perturbative con - densates of quarks and gluons . since hadrons are excitations with respect to the vacuum , hadronic properties are ultimately related to properties of the vacuum . based on the vacuum structure , some hadron properties have been described well . in the low energy region , qcd has two very important proper - ties : chiral symmetry spontaneous breaking and confinement , which are closely related to the vacuum characteristics of qcd . much experiments and theoretical studies have shown that chiral symmetry spontaneous breaking is very important to understand the low - energy feature of the strongly interacting physics , and the quark condensates give an expression to chiral symmetry spontaneous breaking . according to goldstone ' s theorem , the goldstone bosons with zero mass will emerge as the chiral symmetry is spontaneously broken . there are two ways : inear and non - linear methods to carry out this constraint . in our paper , we will use the non - linear method 大量实验和理论研究表明，手征对称自发破缺对于理解低能强相互作用十分重要，而夸克凝聚又是导致手征对称自发破缺的因素。按goldstone理论，伴随手征对称自发破缺应该会有零质量的goldstonebosons产生。而对于这一条件的实现有线性和非线性两种方法本文将用非线性的方法将手征对称自发破缺应用于su ( 3 )模型即重子八重态，得出描述其强相互作用的手征对称自发破缺lagrange密度。
The lund string dynamical model frifiof , luciae model and jpciae model were introduced in the third chapter . luciae model is based on frifiof model , while jpciae model is based on pyth1a . paciae model , a new model based on parton and hadron cascade is being improved and its physical ideas is introduced 论文的第三章主要介绍了建立在lund弦模型基础上的强子和d玄级联的fritiof模型、 luciae模型和jpciae模型，其中luciae模型是建立在frjtiof棋型的基础上，而jpciae模型是建立在pythia的基础之上的。
It takes advantages of modern computer to fit all the experimental information , hence a very powerful pwa method . in this thesis , we use this method to analysis hadrons japdecay model jap - > ( ptt - tr + and j p radioactive decay model based on the pwa amplitude , we received mass distribution of two outgoing pious and angle distribution of the outgoing particles using the cern program . finally we compared tow different form factors ( barrier factors and gauss factor ) wh ich were always used the calculating of pwa amplitude 本文采用这种分析方法给出的j强衰变j ~ - ~ +和j粒子辐射衰变j ~ - ~ +分波振幅公式，利用cern的蒙特卡罗模拟程序绘出了末态粒子的角分布和不变质量分布，对分波分析中常用的两种动力学形状因子(中心位垒因子和高斯压低因子)进行了研究比较。
