作者机构：
[廖峰; 贺三军; 张双; 罗万; 刘丽艳; 赵修良] School of Nuclear Science and Technology, University of South China, Hengyang;421001, China;[廖峰; 贺三军; 张双; 罗万; 刘丽艳; 赵修良] 421001, China
关键词：
碳离子治疗;三维电离室阵列;三维剂量验证
摘要：
为快速准确地实现碳离子治疗计划的三维剂量验证,采用有机玻璃PMMA(聚甲基丙烯酸甲酯)为电离室室壁和水等效模体,设计了一种三维电离室阵列,并通过Geant4软件对三维电离室阵列的结构设计进行了深入研究与验证.首先通过模拟不同能量碳离子束在水和PM M A模体中沉积的剂量分布,计算了PM M A模体的水等效厚度系数;然后研究了三维电离室阵列中电离腔室间的距离及信号导线对其剂量测量准确度的影响;最后模拟并验证了碳离子束在三维电离室阵列中沉积的剂量分布.结果表明:PM M A模体的水等效厚度系数为1.151;相邻电离腔室间的信号串扰主要来源于前侧的电离腔室,且串扰程度与电离腔室间距呈反比,间距为1 mm时串扰程度占电离腔室内剂量的3％,间距为30 m m时串扰影响可完全消除;信号导线对后侧电离腔室内剂量的干扰影响约为1％.将碳离子束在三维电离室阵列中沉积的剂量分布与PM M A模体中的剂量分布进行对比,碳离子束的射程具有良好的一致性,偏差为0.5 mm.
通讯机构：
[Chen, X.] S;School of Nuclear Science and Technology, China
关键词：
triply heavy baryons;holographic QCD;potential energy
摘要：
<jats:title>Abstract</jats:title>
<jats:p>Using gauge/gravity duality, we study the potential energy and the melting of triply heavy baryon at finite temperature and chemical potential in this paper. First, we calculate the three-quark potential and compare the results with quark-antiquark potential. With the increase of temperature and chemical potential, the potential energy will decrease at large distances. It is found that the three-quark potential will have an endpoint at high temperature and/or large chemical potential, which means triply heavy baryons will melt at enough high temperature and/or large chemical potential. We also discuss screening distance which can be extracted from the three-quark potential. At last, we draw the melting diagram of triply heavy baryons in the <jats:inline-formula>
<jats:tex-math><?CDATA $ T-\mu $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_47_1_013106_M1.jpg" xlink:type="simple" />
</jats:inline-formula> plane.</jats:p>
作者机构：
[Luo, Song; Li, Xiao-Hua; Qi, Lin-Jing; Zhang, Dong-Meng] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.;[Wu, Xi-Jun] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Liang, Chun-Tian] Tianjin Chengjian Univ, Sch Sci, Tianjin 300384, Peoples R China.;[Li, Xiao-Hua] Univ South China, Cooperat Innovat Ctr Nucl Fuel Cycle Technol & Equ, Hengyang 421001, Peoples R China.;[Li, Xiao-Hua] Hunan Normal Univ, Key Lab Low Dimens Quantum Struct & Quantum Contro, Changsha 410081, Peoples R China.
关键词：
cluster radioactivity;cluster-formation model (CFM);half-lives;preformation probability
摘要：
<jats:title>Abstract</jats:title>
<jats:p>In the present work, based on the Wentzel-Kramers-Brillouin (WKB) theory, considering the cluster preformation probability (<jats:inline-formula>
<jats:tex-math><?CDATA $ P_{c} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_47_1_014101_M1.jpg" xlink:type="simple" />
</jats:inline-formula>), we systematically investigate the cluster radioactivity half-lives of 22 trans-lead nuclei ranging from <jats:sup>221</jats:sup>Fr to <jats:sup>242</jats:sup>Cm. When the mass number of the emitted cluster <jats:inline-formula>
<jats:tex-math><?CDATA $ A_{c} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_47_1_014101_M3.jpg" xlink:type="simple" />
</jats:inline-formula>
<jats:inline-formula>
<jats:tex-math><?CDATA $ \lt $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_47_1_014101_M4.jpg" xlink:type="simple" />
</jats:inline-formula> 28, <jats:inline-formula>
<jats:tex-math><?CDATA $P_{c} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_47_1_014101_Z-20221112161050.jpg" xlink:type="simple" />
</jats:inline-formula> is obtained by the exponential relationship of <jats:inline-formula>
<jats:tex-math><?CDATA $ P_{c} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_47_1_014101_M5.jpg" xlink:type="simple" />
</jats:inline-formula> to the <jats:italic>α</jats:italic> decay preformation probability (<jats:inline-formula>
<jats:tex-math><?CDATA $ P_{\alpha} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_47_1_014101_M6.jpg" xlink:type="simple" />
</jats:inline-formula>) proposed by R. Blendowskeis <jats:inline-formula>
<jats:tex-math><?CDATA $ et $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_47_1_014101_M7.jpg" xlink:type="simple" />
</jats:inline-formula>
<jats:inline-formula>
<jats:tex-math><?CDATA $ al. $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_47_1_014101_M8.jpg" xlink:type="simple" />
</jats:inline-formula> [Phys. Rev. Lett. <jats:bold>61</jats:bold>, 1930 (1988)], while <jats:inline-formula>
<jats:tex-math><?CDATA $ P_{\alpha} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_47_1_014101_M9.jpg" xlink:type="simple" />
</jats:inline-formula> is calculated through the cluster-formation model (CFM). When <jats:inline-formula>
<jats:tex-math><?CDATA $ A_{c} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_47_1_014101_M10.jpg" xlink:type="simple" />
</jats:inline-formula>
<jats:inline-formula>
<jats:tex-math><?CDATA $ \ge $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_47_1_014101_M11.jpg" xlink:type="simple" />
</jats:inline-formula> 28, <jats:inline-formula>
<jats:tex-math><?CDATA $ P_{c} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_47_1_014101_Z-20221112161420.jpg" xlink:type="simple" />
</jats:inline-formula> is calculated through the charge-number dependence of <jats:inline-formula>
<jats:tex-math><?CDATA $ P_{c} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_47_1_014101_M12.jpg" xlink:type="simple" />
</jats:inline-formula> on the decay products proposed by Ren <jats:inline-formula>
<jats:tex-math><?CDATA $ et $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_47_1_014101_M13.jpg" xlink:type="simple" />
</jats:inline-formula>
<jats:inline-formula>
<jats:tex-math><?CDATA $ al. $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_47_1_014101_M14.jpg" xlink:type="simple" />
</jats:inline-formula> [Phys. Rev. C <jats:bold>70</jats:bold>, 034304 (2004)]. The half-lives of cluster radioactivity have been calculated by the density-dependent cluster model [Phys. Rev. C <jats:bold>70</jats:bold>, 034304 (2004)] and by the unified formula of half-lives for alpha decay and cluster radioactivity [Phys. Rev. C <jats:bold>78</jats:bold>, 044310 (2008)]. For comparison, a universal decay law (UDL) proposed by Qi <jats:inline-formula>
<jats:tex-math><?CDATA $ et $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_47_1_014101_M15.jpg" xlink:type="simple" />
</jats:inline-formula>
<jats:inline-formula>
<jats:tex-math><?CDATA $ al. $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_47_1_014101_M16.jpg" xlink:type="simple" />
</jats:inline-formula> [Phys. Rev. C <jats:bold>80</jats:bold>, 044326 (2009)], a semi-empirical model for both <jats:italic>α</jats:italic> decay and cluster radioactivity proposed by Santhosh [J. Phys. G: Nucl. Part. Phys. <jats:bold>35</jats:bold>, 085102 (2008)], and a unified formula of half-lives for alpha decay and cluster radioactivity [Phys. Rev. C <jats:bold>78</jats:bold>, 044310 (2008)] are also used. The calculated results of our work, Ni's formula , and the UDL can well reproduce the experimental data and are better than those of Santhosh's model. In addition, we extend this model to predict the half-lives for 51 nuclei, whose cluster radioactivity is energetically allowed or observed but not yet quantified in NUBASE2020.</jats:p>
作者机构：
[赵鹏程; Zeng F.; 向钊才] School of Nuclear Science and Technology, University of South China, Hengyang, 421001, China
通讯机构：
[Zhao, P.] S;School of Nuclear Science and Technology, China
关键词：
环形燃料元件;热工性能;几何尺寸修正;导热模型;流量分配比
摘要：
针对环形燃料元件，基于欧洲铅冷系统反应堆ELSY选取环形燃料元件参数，建立环形燃料元件导热模型，设定环形燃料元件的初始参数并利用MATLAB编制环形燃料元件导热计算程序，通过制定的三个评估标准研究环形燃料流量分配比、内外包壳厚度、内外气隙厚度和芯块厚度对环形燃料元件热工性能的影响并进行几何尺寸修正。研究结果表明：适当增大流量分配比、减小内包壳厚度、增大外包壳厚度、减小内外气隙间距和减小芯块厚度可改善元件的热工性能；设定流量分配比为1、内包壳厚度0.06 cm修正为0.04 cm、外包壳厚度0.06 cm修正为0.07 cm、内外气隙间距0.035 cm修正为0.015 cm、芯块厚度修正为0.05 cm，进行这些几何尺寸修正后，芯块的最高温度下降了90 K（8.6%），绝热面位置偏离芯块几何中心不足2 μm，内外通道冷却剂出口温差不足2 K，环形燃料元件热工性能得到了明显提高。 Background
Compared with conventional rod-type nuclear fuel, annular fuel has higher power density and better heat transfer efficiency, which can significantly improve the safety and economy of the reactor.
Purpose
This study aims to investigate the effect of ring fuel element geometry on the thermal performance and to correct the initial parameters.
Methods
The initial parameters of the ring fuel element were set and the thermal conductivity calculation program of the ring fuel element was prepared. The effects of the ring fuel flow distribution ratio, inner and outer cladding thickness, inner and outer air gap thickness and core block thickness on the thermal performance of the ring fuel element were investigated by three evaluation criteria developed and geometric corrections are made.
Results
Appropriately increasing the flow distribution ratio, decreasing the inner casing thickness, increasing the outer casing thickness, decreasing the inner and outer air gap spacing and decreasing the core block thickness can improve the thermal performance of the components; setting the flow distribution ratio to 1, the inner casing thickness 0.06 cm is amended to 0.04 cm, the outer casing thickness 0.06 cm is amended to 0.07 cm, the inner and outer air gap spacing 0.035 cm. The thickness of core block is amended to 0.5 cm.
Conclusions
Thermal performance of annular fuel elements is significantly improved after appropriate geometry correction is made.
作者机构：
[朱恩平; 王婷; 刘紫静; 赵鹏程; 王天石] School of Nuclear Science and Technology, University of South China, Hengyang;421001, China;[朱恩平; 王婷; 刘紫静; 赵鹏程; 王天石] 421001, China
通讯机构：
School of Nuclear Science and Technology, University of South China, Hengyang, China
通讯机构：
[Chen, Z.] S;School of Nuclear Science and Technology, China
关键词：
辐射屏蔽;高维多目标问题;屏蔽结构优化;核反应堆
摘要：
辐射屏蔽设计是反应堆设计的重要组成，面向陆海空天全域的新型核动力技术的发展对辐射屏蔽优化设计方法提出了新需求。采用传统屏蔽结构多目标优化方法处理三维屏蔽结构优化问题时，存在寻优速度慢、难以收敛、全局性差等缺陷，基于第三代非支配排序遗传算法（Non-dominated Sorting Genetic Algorithm Ⅲ，NSGA-Ⅲ），开展面向三维屏蔽结构设计的高维多目标优化方法研究。基于核反应堆三维屏蔽结构模型，以屏蔽层重量、体积和特定区域辐射剂量率为优化目标，开展NSGA-III优化方法的性能对比分析研究。数值结果表明：本文建立的高维多目标优化方法可更高效、稳定地搜寻Pareto前沿解，可为辐射屏蔽设计优化提供新思路。 Background Radiation shielding design is an important part of reactor design, and the development of new nuclear power technology for various kinds of reactors has put forward new demands on radiation shielding optimization design methods. Purpose This study aims to overcome the shortcomings of the traditional multi-objective optimization methods for shielding structures in dealing with the optimization problem of 3D shielding structures, such as slow optimization speed, difficulty in convergence, and poor globalization. Methods Based on the non-dominated sorting genetic algorithm Ⅲ (NSGA-Ⅲ), the many-objective optimization method for 3D shielding structure design for nuclear reactor was proposed. The Monte Carlo N-Particle Transport Code (MCNP) was employed to analyze comparative performance of the NSGA-III optimization method on the basis of the 3D shielding structure model of nuclear reactors, and shield weight, volume and radiation dose rate in specific regions were taken as the optimization targets. Results & Conclusions The numerical simulation results show that the NSGA-III based optimization method for 3D shielding structure design can search for the Pareto-optimal front more efficiently and stably, providing a new idea for the optimization of radiation shielding design.
作者机构：
[李铸伦; 谢金森; 徐士坤; 邓年彪; 苑旭东; 于涛] School of Nuclear Science and Technology, University of South China, Hengyang;421001, China;Research Center for Digital Nuclear Reactor Engineering and Technology of Hunan Province, University of South China, Hengyang;[李铸伦; 谢金森; 徐士坤; 邓年彪; 苑旭东; 于涛] 421001, China <&wdkj&> Research Center for Digital Nuclear Reactor Engineering and Technology of Hunan Province, University of South China, Hengyang;[李铸伦; 谢金森; 徐士坤; 邓年彪; 苑旭东; 于涛] 421001, China
作者机构：
[罗万; 赵修良] School of Nuclear Science and Technology, University of South China, Hengyang, 421000, China;[刘雅兰; 杨大伟; 姜仕林] Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
摘要：
Aneutronic fusion reactions such as proton–boron fusion could efficiently produce clean energy with quite low neutron doses. However, as a consequence, conventional neutron spectral methods for diagnosing plasma ion temperature would no longer work. Therefore, finding a way to probe the ion temperature in aneutronic fusion plasmas is a crucial task. Here, we present a method to realize ultrafast in situ probing of 11B ion temperature for proton–boron fusion by Doppler broadening of the nuclear resonance fluorescence (NRF) emission spectrum. The NRF emission is excited by a collimated, intense γ-ray beam generated from submicrometer wires irradiated by a recently available petawatt (PW) laser pulse, where the γ-ray beam generation is calculated by three-dimensional particle-in-cell simulation. When the laser power is higher than 1 PW, five NRF signatures of a 11B plasma can be clearly identified with high-resolution γ-ray detectors, as shown by our Geant4 simulations. The correlation between the NRF peak width and 11B ion temperature is discussed, and it is found that NRF emission spectroscopy should be sensitive to 11B ion temperatures Ti > 2.4 keV. This probing method can also be extended to other neutron-free-fusion isotopes, such as 6Li and 15N.
