作者：
Yuan, T.;Chen, M.*;Yu, J. Y.;Liu, W. Y.;Luo, W.;...
期刊：
PHYSICS OF PLASMAS,2017年24(6):063104 ISSN：1070-664X
通讯作者：
Chen, M.
作者机构：
[Chen, M.; Sheng, Z. M.; Yu, J. Y.; Weng, S. M.; Yuan, T.] Shanghai Jiao Tong Univ, Key Lab Laser Plasmas, Minist Educ, Shanghai 200240, Peoples R China.;[Chen, M.; Sheng, Z. M.; Yu, J. Y.; Weng, S. M.; Yuan, T.] Shanghai Jiao Tong Univ, Dept Phys, Shanghai 200240, Peoples R China.;[Chen, M.; Sheng, Z. M.; Yu, J. Y.; Weng, S. M.; Yuan, T.] Shanghai Jiao Tong Univ, CICIFSA, Shanghai 200240, Peoples R China.;[Luo, W.; Liu, W. Y.] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.;[Luo, W.; Sheng, Z. M.] Univ Strathclyde, Dept Phys, SUPA, Glasgow G4 0NG, Lanark, Scotland.
摘要：
Pair production from the Breit-Wheeler process in ultra-intense laser pulse interactions with solid targets are studied by particle-in-cell simulations using the EPOCH code including the quantum electrodynamics module. We find that the pair yield depends on both the target transverse size and the laser pulse duration. For a short laser pulse, the highest pair yield is achieved with a target as wide as the laser spot size. For a long laser pulse, however, the optimal target size for the pair production increases with the pulse duration due to a self-generated cone by the hole-boring process. The effect of laser polarization upon the pair production is also studied. It is found that a circularly polarized laser pulse is more efficient in the ion acceleration rather than in the pair production. With the same laser energy, we find that a linearly polarized laser pulse can generate two times more positrons than the circularly polarized laser pulse does. These findings may benefit the future researches on the laser plasma based electron-positron production.
作者机构：
[朱志超; 宋英明; 梁烨; 叶凯萱; 邹树梁; 颜佳伟; 张震宇; 张秋楠] School of Nuclear Science and Technology, University of South China, Hengyang, 421001, China;[王宁] Center of Information, Nuclear Power Institute of China, Chengdu, 610213, China
关键词：
核设施退役;辐射场重构;拆除路径优化;功能软件
摘要：
辐射场分布和路径选择是核设施退役过程中影响工作人员吸收剂量的主要因素。针对核设施退役过程中多源项的三维辐射场,采用点核积分的方法进行重构,重构结果与蒙特卡罗程序计算结果吻合很好,验证了点核积分法的可行性。将核退役拆除路径问题抽象为一种类旅行商问题数学模型,构造不同拆除路径下所受外照射剂量对应的剂量矩阵,根据辐射防护ALARA (As Low As Reasonably Achievable)原则,利用遗传算法进行寻优。对于多源项退役拆除实例,计算给出了最优化拆除路径和三维可视化显示,并对优化效果进行了讨论。设计开发了面向核设施退役过程的辐射场重构与拆除路径优化功能软件。
作者机构：
[谭军文; 张振朝; 左国平; 周扬; 张帆] School of Nuclear Science and Technology, University of South China, Hengyang, 421001, China
通讯机构：
[Zuo, G.] S;School of Nuclear Science and Technology, University of South China, Hengyang, China
关键词：
g射线;三晶体耦合;放射源定位
摘要：
为了快速定位并寻回丢失的放射源,设计了一种由NaI、CsI、锗酸铋(Bi_4Ge_3O_(12), BGO)三种晶体与铅耦合组成的γ射线方向探测器,并采用基于蒙特卡罗方法的通用软件包MCNP(Monte Carlo N Particle Transport Code)研究了铅晶比例、射线能量、剂量率等因素对探测器角度分辨率的影响。结果表明,对于~(137)Cs源,在空气吸收剂量率≥0.331 μGy·h~(–1)处,定位角度偏差≤0.99°;对于~(60)Co源,在空气吸收剂量率0.586 μGy·h~(–1)处,测量的平均角度偏差为0.46°;对于水平距离7 m、高度4 m的3.7×10~7 Bq ~(137)Cs源,相对定位偏差约为5%。
作者机构：
[赵文博; 谢芹; 何丽华; 谢金森; 刘紫静; 于涛; 陈珍平; Zeng W.] School of Nuclear Science and Technology, University of South China, Hengyang, 421001, China
通讯机构：
[Yu, T.] S;School of Nuclear Science and Technology, University of South China, Hengyang, China
关键词：
熔盐堆;组件均匀化;ThU燃料;TRU燃料
摘要：
DRAGON&DONJON组件-堆芯“两步法”程序通过合理简化,理论可适用于任何堆芯与工况。使用蒙特卡罗方法RMC(Reactor Monte Carlo code)、MCNP(Monte Carlo Neutron Particle transport code)程序验证DRA&DON程序是否能够承担快/热谱型熔盐堆(Molten Salt Reactor, MSR)焚烧TRU、ThU燃料燃耗计算。选出熔盐增殖堆(Molten Salt Breeder Reactor, MSBR)与熔盐锕系元素再循环和嬗变堆(Molten Salt Advanced Reactor Transmuter, MOSART)堆型进行比较,同时分别利用RMC程序验证DRAGON程序组件燃耗计算的准确性,利用MCNP程序验证DRAGON程序组件均匀化方法以及DONJON程序截面调用和程序全堆扩散的准确性。结果表明,组件燃耗计算中,TRU和ThU燃料满足燃耗计算要求;堆芯临界计算中,快/热谱堆芯计算误差均小于0.001。证明DRA&DON程序可以胜任快、热谱型MSR焚烧TRU、ThU燃料的物理计算任务。
摘要：
Abstract: This paper introduces the basic principle of γ-γ coincidence method for measuring the activity of radioactive source, and the setting method of each plug-in parameter is described in order to achieve the highest precision. The influence of the measurement time on the measurement results is discussed in detail, and the accuracy of the measurement method can be achieved under the condition of the method. The experimental results show that the best measurement time is 100 s. The activity of the 60Co radioactive source is 142,620 ± 924 Bq, the measurement accuracy is 308 Bq, and the relative deviation of the measurement result is 0.217%. The experiment turns out that the activity and experimental time the relative deviation of the reference activity of the source is 1.09%, which is consistent within the error range.#@#@#摘要: 本文介绍了γ-γ符合法测量放射源活度的基本原理，阐述实验过程中为达到最高精度，各个插件参数的设置方法；详细讨论了测量时间对测量结果的影响，并讨论在该条件下符合法测量源活度能够达到的精度。实验结果表明：最佳测量时间为100 s；符合法实验测得60Co放射源的活度为142,620 ± 924 Bq，测量精度为308 Bq，测量结果的相对偏差为0.217%；实验所得的源活度与实验时源的参考活度相对偏差为1.09%，在误差范围内一致。
摘要：
In this work, a facile method was adopted to synthesize molybdenum disulfide/reduced graphene oxide (MoS_2/rGO) composites through an L-cysteine-assisted hydrothermal technique. The as-prepared MoS_2/ rGO composites were firstly applied as adsorbents for efficient elimination of Pb(II) ions. Batch adsorption experiments showed that the adsorption of Pb(II) on MoS_2/rGO followed pseudo-second-order kinetic model well. The adsorption of Pb(II) was intensely pH-dependent, ionic strength-dependent at pH < 9.0 and ionic strength-independent at pH > 9.0. The presence of humic acid (HA) enhanced Pb(II) adsorption obviously. The MoS_2/rGO composites exhibited excellent adsorption capacity of 384.16 mg g~(-1) at pH 5.0 and T=298.15 K, which was superior to MoS_2 (279.93 mg g~(-1)) and many other adsorbents. The thermodynamic parameters suggested that the adsorption process of Pb(II) on MoS_2/rGO composites was spontaneous (?G~θ < 0) and endothermic (?H~θ > 0). The interaction of Pb(II) and MoS_2/ rGO was mainly dominated by electrostatic attraction and surface complexation between Pb(II) and oxygen-containing functional groups of MoS_2/rGO. This work highlighted the application of MoS_2/rGO as novel and promising materials in the efficient elimination of Pb(II) from contaminated water and industrial effluents in environmental pollution management.
