发表机构
New Uzbekistan University; Institute of Nuclear Physics（新乌兹别克斯坦大学; 核物理研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究针对$^{48}$Ca+$^{244}$Pu反应合成超重核$^{292}$Fl的存活概率，对比传统与耦合的蒸发-裂变级联处理，发现因子化方法显著低估$3n$道存活概率，且冷裂变势垒微小差异会大幅改变存活概率。
AI 中文摘要
激发态复合核抵抗裂变的存活概率$W_{\rm sur}$是决定超重核合成中蒸发剩余截面的关键因素。本文研究了$^{48}$Ca+$^{244}$Pu反应中形成的$^{292}$Fl的$W_{\rm sur}$，特别关注退激级联过程中中子多重性与裂变竞争的耦合作用。入射道俘获与融合截面通过双核系统模型获取，而中子-裂变竞争采用Vandenbosch-Huizenga形式主义处理，结合Kramers和Strutinsky修正，以及随温度和角动量阻尼的裂变势垒。采用两种蒸发-裂变级联处理方法计算存活概率：在传统的因子化方法中，给定$xn$道的实现概率独立于中子-裂变竞争，分支比沿平均激发能轨迹计算；在耦合方法中，完整的激发能布居随级联传播，因此中子多重性与裂变竞争在每个核实际达到的能量处同时确定。对比结果显示，因子化处理在$E^*=39$ MeV和47 MeV时，对$3n$道存活概率的低估倍数分别为17和24，而其对$4n$道的影响则小得多。由此得到的$3n$和$4n$蒸发剩余激发函数，在两倍因子范围内重现了14个测量截面中的8个。对两种冷裂变势垒方案的进一步对比表明，小于1 MeV的差异可使$W_{\rm sur}$变化超过一个数量级。
英文摘要
The survival probability $W_{\rm sur}$ of an excited compound nucleus against fission is a key factor determining the evaporation-residue cross section in the synthesis of superheavy nuclei. The $W_{\rm sur}$ for $^{292}$Fl formed in the $^{48}$Ca+$^{244}$Pu reaction was investigated, with particular attention to the coupling between neutron multiplicity and fission competition during the de-excitation cascade. The entrance-channel capture and fusion cross sections are obtained within the dinuclear system model, while the neutron--fission competition is treated using the Vandenbosch--Huizenga formalism with the Kramers and Strutinsky corrections and a fission barrier damped with temperature and angular momentum. The survival probability is calculated using two treatments of the evaporation--fission cascade. In the conventional factorized approach, the realization probability of a given $xn$ channel is treated independently of the neutron--fission competition, with the branching ratios evaluated along a mean excitation-energy trajectory. In the coupled approach, the full excitation-energy population is propagated through the cascade, so that neutron multiplicity and competition with fission are determined simultaneously at the energy actually reached by each nucleus. The comparison shows that the factorized treatment underestimates the $3n$ survival probability by factors of 17 and 24 at $E^*=39$ and 47 MeV, respectively, while its effect on the $4n$ channel is considerably smaller. The resulting $3n$ and $4n$ evaporation-residue excitation functions reproduce eight of the fourteen measured cross sections within a factor of two. A comparison of two prescriptions for the cold fission barrier further shows that differences of less than 1 MeV can change $W_{\rm sur}$ by more than an order of magnitude.
Comments15 pages, 6 figures
