Production of unknown neutron-rich isotopes in U-238+U-238 collisions at near-barrier energy
Production of unknown neutron-rich isotopes in U-238+U-238 collisions at near-barrier energy
复制标题
U-238 近势垒能量碰撞中产生未知的富中子同位素
DOI：
10.1103/physrevc.94.024601
复制
发表时间：
2016
影响因子：
3.1
通讯作者：
Wu Xizhen
中科院分区：
文献类型：
--
作者：
Zhao Kai;Li Zhuxia;Zhang Yingxun;Wang Ning;Li Qingfeng;Shen Caiwan;Wang Yongjia;Wu Xizhen
用改进的量子分子动力学模型（ImQMD）结合统计蒸发模型（hivapcode）计算了7.0MeV/核子碰撞中电荷数为~120的初级碎片和剩余碎片的产生截面。计算结果预测，在该反应中，从Ra（）到Db（），大约有60种未知丰中子同位素的产生截面在mb下限以上。几乎所有未知的富中子同位素都是在实验室角度发射的。两种情况，即，本文研究了铀的未知同位素和铷的未知同位素的产生，以了解未知丰中子同位素的产生机制。结果表明，前一种情况下，两个铀核的碰撞时间较短，产生剩余物的初级碎片具有较小的激发能MeV，剩余物的出射角范围为.对于后一种情况，大量的核子被转移需要较长的碰撞时间，从而导致较高的激发能和较小的初级碎片出射角，并最终导致具有较小出射角间隔的Rf残基的产生截面非常小。
The production cross sections for primary and residual fragments with charge number fromto 120 produced in the collision ofat 7.0 MeV/nucleon are calculated by the improved quantum molecular dynamics (ImQMD) model incorporated with the statistical evaporation model (hivapcode). The calculation results predict that about 60 unknown neutron-rich isotopes from elements Ra () to Db () can be produced with the production cross sections above the lower bound ofmb in this reaction. And almost all of the unknown neutron-rich isotopes are emitted at the laboratory angles. Two cases, i.e., the production of the unknown uranium isotopes withand that of rutherfordium with, are investigated to understand the production mechanism of unknown neutron-rich isotopes. It is found that for the former case the collision time between two uranium nuclei is shorter and the primary fragments producing the residues have smaller excitation energies ofMeV and the outgoing angles of those residues cover a range of. For the latter case, a longer collision time is needed for a large number of nucleons being transferred and thus it results in higher excitation energies and smaller outgoing angles of primary fragments, and eventually results in a very small production cross section for the residues of Rf withwhich have a small interval of outgoing angles of.