Synthesis of superheavy nuclei: How accurately can we describe it and calculate the cross-sections?
Synthesis of superheavy nuclei: How accurately can we describe it and calculate the cross-sections?
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DOI：
10.1103/physrevc.65.014607
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发表时间：
2001-12
影响因子：
3.1
通讯作者：
V. Zagrebaev;Y. Aritomo;M. Itkis;Y. Oganessian;M. Ohta
中科院分区：
文献类型：
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作者：
V. Zagrebaev;Y. Aritomo;M. Itkis;Y. Oganessian;M. Ohta
本文对重离子聚变反应导致重蒸发残渣形成的各个阶段进行了全面的分析。分析的主要目的是更好地了解整个过程，并找出哪些因素和量，特别是哪些因素和量，给计算的截面带来了主要的不确定性，超重元素形成截面的计算有多可靠，以及在这一领域还应进行哪些理论和实验研究。由于新的1 -4 #实验结果表明在所谓的“稳定岛”区域产生和研究超重核是真实的可能性，最近人们对超重核合成的兴趣日益增长。"新的现实要求这些昂贵的实验有更坚实的理论支持，这将允许更合理地选择聚变核和碰撞能量，以及更好地估计截面和蒸发残余物~ER！不幸的是，目前这是相当困难的~几乎不可能！对导致易裂变超重核在ER出口通道中形成的重离子聚变反应的复杂动力学进行了准确的定性分析。然而，最近出现了一些推测性的论文，它们用相当简化的模型对新超重元素与不同碰撞核反应的形成截面值进行了预测。在本研究中，对所有反应阶段进行了全面的分析。它的目的是更好地理解我们如何在实验理论模型的框架内描述它们，截面对什么量敏感，这些量的值有多准确，最后，没有实验数据的反应中产生的重ER的截面的预测有多准确。本文给出了两个重核A_（11）A_（2！C！B 1 n，p，a，g在质心能量接近库仑势垒的入口通道，通常分解在分波和s ER 11 A2！B ~ E！' p\ 2
A thorough analysis of all stages of heavy ion fusion reaction leading to the formation of a heavy evapora- tion residue has been performed. The main goal of the analysis was to gain better understanding of the whole process and to find out what factors and quantities, in particular, bring major uncertainty into the calculated cross sections, how reliable the calculation of the cross sections of superheavy element formation may be and what additional theoretical and experimental studies should be made in this field. The interest in the synthesis of superheavy nuclei has lately grown due to the new experimental results @1-4 # dem- onstrating a real possibility of producing and investigating the nuclei in the region of the so-called ''island of stability.'' The new reality demands a more substantial theoretical sup- port of these expensive experiments which will allow a more reasonable choice of fusing nuclei and collision energies as well as a better estimation of the cross sections and unam- biguous identification of evaporation residues ~ER!. Unfortu- nately, at present it is quite difficult ~and hardly possible! to make an accurate qualitative analysis of the complex dynam- ics of the heavy ion fusion reaction leading to the formation in the exit channel of ER of easily fissile superheavy nucleus. However, lately a number of speculative papers have ap- peared in which predictions are made in terms of rather sim- plified models concerning the values of formation cross sec- tions of new superheavy elements in reactions with different colliding nuclei. A thorough analysis of all reaction stages is made in the present study. It is aimed at better understanding of how well we can describe them in the framework of ex- isting theoretical models, what quantities the cross sections are sensitive to and how accurate the values of these quanti- ties have been determined, and finally, how accurate are the predictions of the cross sections of the heavy ER produced in reactions for which no experimental data are available. The production cross section of a cold residual nucleus B, which is the product of light particle evaporation and g emis- sion from an excited compound nucleus C, formed in the fusion process of two heavy nuclei A11A2!C!B 1n, p,a,g at a center-of mass energy close to the Coulomb barrier in the entrance channel, is usually decomposed over partial waves and given by s ER11A2!B ~ E!' p\ 2