分类： 物理学 >> 核物理学 提交时间： 2023-10-07
摘要： This article presents a comprehensive study on the fission process in Th, U, Pu, and Cm isotopes using a Yukawa-folded mean-field plus standard pairing model. The focus is on analyzing the effects of the pairing interaction on the fragment mass distribution and its dependence on nuclear elongation. The study demonstrates that the pairing interaction plays an important role in the fragment mass distribution for $^{230}$Th, $^{234}$U, $^{240}$Pu, and $^{246}$Cm. Numerical analysis reveals that increasing the pairing interaction strength leads to a decrease in asymmetric fragment mass distribution and an increase in symmetric distribution. Furthermore, the investigation examines the odd-even mass differences at symmetric and asymmetric fission points, highlighting their sensitivity to changes in the pairing interaction strength. The systematic analysis of Th, U, Pu, and Cm isotopes' fragment mass distributions demonstrates the effectiveness of the model in reproducing experimental data. Additionally, the study explores the effects of the zero-point energy parameter and neck-breaking probability parameter on the fragment mass distribution for $^{240}$Pu. In conclusion, this research provides valuable insights into the fission process by emphasizing the importance of the pairing interaction and its relationship with nuclear elongation.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Jin-Long Xu
Chuan-Peng Zhang
Naiping Yu
Ming Zhu
Peng Jiang
Jie Wang
Xin Guan
Xiao-Lan Liu
Xiaolian Liang
the FAST Collaboration
摘要： We present a new high-sensitivity HI observation toward nearby spiral galaxy M101 and its adjacent 2$^{\circ}\times$ 2$^{\circ}$ region using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). From the observation, we detect a more extended and asymmetric HI disk around M101. While the HI velocity field within the M101's optical disk region is regular, indicating that the relatively strong disturbance occurs in its outer disk. Moreover, we identify three new HI clouds located on the southern edge of the M101's HI disk. The masses of the three HI clouds are 1.3$\times$10$^{7}$ $M_{\odot}$, 2.4$\times$10$^{7}$ $M_{\odot}$, and 2.0$\times$10$^{7}$ $M_{\odot}$, respectively. The HI clouds similar to dwarf companion NGC 5477 rotate with the HI disk of M101. Unlike the NGC 5477, they have no optical counterparts. Furthermore, we detect a new HI tail in the extended HI disk of M101. The HI tail detected gives a reliable evidence for M101 interaction with the dwarf companion NGC 5474. We argue that the extra-planar gas (three HI clouds) and the HI tail detected in the M101's disk may origin from a minor interaction with NGC 5474.
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