CAJ | 학술논문

用改进的量子分子动力学模型研究了重核强阻尼反应过程中巨复合体系的形成和衰变机制。计算了强阻尼反应^238U＋^238U和^232Th＋^250Cf的入射道动力学势、绝热势和密度冻结势并对它们进行了比较，我们发现动力学势与绝热势非常接近，相对于非常陡峭的密度冻结势来说，在弹靶接触位型阶段两者都变的比较平坦。正因为这种比较平坦的相互作用势使巨复合体系能够存活一定的时间。通过不同能量下反应体系的密度分布随时间的演化，从而得到每个反应事件形成巨复合体系的寿命，进一步给出复合体系的寿命分布和平均寿命的能量依赖关系。研究表明：选择合适的入射能量可以使强阻尼反应形成的复合体系有最长的寿命。在动量空间中，通过复合体系形变的各向异性作为入射能量的函数的研究，发现使形成的巨复合体系具有各向同性的动量分布所对应的能量是最佳入射能量的选择，它能使复合体系保持最长的寿命，这种情况最有利于正电子的产生。
용개진적양자분자동역학모형연구료중핵강조니반응과정중거복합체계적형성화쇠변궤제。계산료강조니반응^238U＋^238U화^232Th＋^250Cf적입사도동역학세、절열세화밀도동결세병대타문진행료비교，아문발현동역학세여절열세비상접근，상대우비상두초적밀도동결세래설，재탄파접촉위형계단량자도변적비교평탄。정인위저충비교평탄적상호작용세사거복합체계능구존활일정적시간。통과불동능량하반응체계적밀도분포수시간적연화，종이득도매개반응사건형성거복합체계적수명，진일보급출복합체계적수명분포화평균수명적능량의뢰관계。연구표명：선택합괄적입사능량가이사강조니반응형성적복합체계유최장적수명。재동량공간중，통과복합체계형변적각향이성작위입사능량적함수적연구，발현사형성적거복합체계구유각향동성적동량분포소대응적능량시최가입사능량적선택，타능사복합체계보지최장적수명，저충정황최유리우정전자적산생。
The mechanism of giant composite systems （GCS） form and decay in strongly damped collisions is investigated. The dynamic, adiabatic and frozen density approximation entrance channel potentials in strongly damped reactions of ^238U＋^238U ^232Th＋^250Cf are calculated and compared. By means of the improved quantum molecular dynamics （ImQMD） model the time evolution of the density distribution of ^238U＋^238U ^232Th＋^250Cf at different incident energies are investigated, from which the lifetimes of the GCS at different energies are obtained. The lifetime distribution of the GCS, the average lifetime of the formed GCS and its dependence on incident energies are investigated. The longest average lifetime of the GCS is about 1200fm/c when the incident energy is suitably chosen. The shapes of giant composite systems are found to be largely deformed. The orientation of the deformed composite system changes from 0（180） to 90（270）, when energy increasing from 680 to 1880 MeV. The anisotropy in the momentum space of the GCS as function of incident energies is investigated and it is found that the longest lifetime of the GCS exists with isotropie momenturn distribution at the special incident energy, and the probability of spontaneous positron emission is in this case. largest