检索结果-内蒙古大学图书馆

science Bulletin 2023年第17期68卷 1857-1861页

作者：谢雨耿金军朱熹炜赵忠海雷柱袁文强赵刚吴雪峰乔宾 State Key Laboratory of Nuclear Physics and Technology Center for Applied Physics and Technologyand HEDPSSchool of PhysicsPeking UniversityBeijing 100094China Research Center of Laser Fusion China Academy of Engineering PhysicsMianyang 621900China Purple Mountain Observatory Chinese Academy of SciencesNanjing 210023China Key Laboratory for Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100094China School of Astronomy and Space Sciences University of Science and Technology of ChinaHefei 230026China Frontiers Science Center for Nano-optoelectronic Peking UniversityBeijing 100094China

快速射电暴(FRB)是宇宙中短时标的射电闪耀现象.近期,来自于SGR 1935+2154的一个独特的FRB(FRB 200428)和非热X射线爆发的成协的天文探测,证实了FRB起源于磁坨星的可能性.然而,无论是快速射电暴还是非热X射线的物理起源都不确定.制约相... 详细信息

快速射电暴(FRB)是宇宙中短时标的射电闪耀现象.近期,来自于SGR 1935+2154的一个独特的FRB(FRB 200428)和非热X射线爆发的成协的天文探测,证实了FRB起源于磁坨星的可能性.然而,无论是快速射电暴还是非热X射线的物理起源都不确定.制约相关研究进展的重要的原因之一是磁坨星磁层附近磁场强度接近施温格极限,此时量子电动力学(QED)效应(特别是正负电子对产生效应)主导了相对论等离子体过程,使其超快、超强的能量释放的过程异常复杂.本文针对这类磁陀星附近的非热X-ray产生机制提出了精确的理论模型,将小尺度的QED磁重联加速与大尺度的光子辐射以及多次康普顿散射自洽地耦合在一起,进行了跨尺度的数值模拟.其数值结果与我国慧眼卫星Insight-HXMT的观测数据的时间和光谱特征非常一致,表明与FRB成协的X射线暴可能来自磁陀星磁层内的QED重联过程.这类模拟方法可以推广到更为广泛、复杂的跨尺度天体物理现象的研究.

关键词：量子电动力学康普顿散射正负电子对 X射线磁重联光子辐射能量释放对应体

来源：评论

学校读者我要写书评

暂无评论

Target Density Effects on Charge Transfer of Laser-Accelerated Carbon Ions in Dense Plasma

引用

Physical Review Letters 2023年第9期130卷 095101-095101页

作者： Jieru Ren Bubo Ma Lirong Liu Wenqing Wei Benzheng Chen Shizheng Zhang Hao Xu Zhongmin Hu Fangfang Li Xing Wang Shuai Yin Jianhua Feng Xianming Zhou Yifang Gao Yuan Li Xiaohua Shi Jianxing Li Xueguang Ren Zhongfeng Xu Zhigang Deng Wei Qi Shaoyi Wang Quanping Fan Bo Cui Weiwu Wang Zongqiang Yuan Jian Teng Yuchi Wu Zhurong Cao Zongqing Zhao Yuqiu Gu Leifeng Cao Shaoping Zhu Rui Cheng Yu Lei Zhao Wang Zexian Zhou Guoqing Xiao Hongwei Zhao Dieter H. H. Hoffmann Weimin Zhou Yongtao Zhao MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter School of Physics Xi’an Jiaotong University Xi’an 710049 China Science and Technology on Plasma Physics Laboratory Laser Fusion Research Center China Academy of Engineering Physics Mianyang 621900 China Advanced Materials Testing Technology Research Center Shenzhen University of Technology Shenzhen 518118 China Institute of Applied Physics and Computational Mathematics Beijing 100094 China Graduate School China Academy of Engineering Physics Beijing 100088 China Institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China School of Nuclear Science and Technology University of Chinese Academy Sciences Beijing 101408 China

We report on charge state measurements of laser-accelerated carbon ions in the energy range of several MeV penetrating a dense partially ionized plasma. The plasma was generated by irradiation of a foam target with laser-induced hohlraum radiation in the soft x-ray regime. We use the tricellulose acetate (C9H16O8) foam of 2 mg/cm3 density and 1 mm interaction length as target material. This kind of plasma is advantageous for high-precision measurements, due to good uniformity and long lifetime compared to the ion pulse length and the interaction duration. We diagnose the plasma parameters to be Te=17 eV and ne=4×1020 cm−3. We observe the average charge states passing through the plasma to be higher than those predicted by the commonly used semiempirical formula. Through solving the rate equations, we attribute the enhancement to the target density effects, which will increase the ionization rates on one hand and reduce the electron capture rates on the other hand. The underlying physics is actually the balancing of the lifetime of excited states versus the collisional frequency. In previous measurement with partially ionized plasma from gas discharge and z pinch to laser direct irradiation, no target density effects were ever demonstrated. For the first time, we are able to experimentally prove that target density effects start to play a significant role in plasma near the critical density of Nd-glass laser radiation. The finding is important for heavy ion beam driven high-energy-density physics and fast ignitions. The method provides a new approach to precisely address the beam-plasma interaction issues with high-intensity short-pulse lasers in dense plasma regimes.

关键词： Electronic excitation & ionization High-energy-density plasmas Plasma fusion Plasma-beam interactions Laboratory plasma Near-critical & underdense plasmas Ab initio molecular dynamics First-principles calculations in plasma physics Particle plasma measurements

来源：评论

学校读者我要写书评

暂无评论

Partial observation can induce mechanistic mismatches in data-constrained models of neural dynamics 38

Partial observation can induce mechanistic mismatches in dat...

引用

38th Conference on Neural Information Processing Systems, NeurIPS 2024

作者： Qian, William Zavatone-Veth, Jacob A. Ruben, Benjamin S. Pehlevan, Cengiz Biophysics Graduate Program Harvard University CambridgeMA02138 United States Kempner Institute for the Study of Natural and Artificial Intelligence Harvard University CambridgeMA02138 United States John A. Paulson School of Engineering and Applied Sciences Harvard University CambridgeMA02138 United States Center for Brain Science Harvard University CambridgeMA02138 United States Department of Physics Harvard University CambridgeMA02138 United States

One of the central goals of neuroscience is to gain a mechanistic understanding of how the dynamics of neural circuits give rise to their observed function. A popular approach towards this end is to train recurrent neural networks (RNNs) to reproduce experimental recordings of neural activity. These trained RNNs are then treated as surrogate models of biological neural circuits, whose properties can be dissected via dynamical systems analysis. How reliable are the mechanistic insights derived from this procedure? While recent advances in population-level recording technologies have allowed simultaneous recording of up to tens of thousands of neurons, this represents only a tiny fraction of most cortical circuits. Here we show that observing only a subset of neurons in a circuit can create mechanistic mismatches between a simulated teacher network and a data-constrained student, even when the two networks have matching single-unit dynamics. In particular, partial observation of models of low-dimensional cortical dynamics based on functionally feedforward or low-rank connectivity can lead to surrogate models with spurious attractor structure. Our results illustrate the challenges inherent in accurately uncovering neural mechanisms from single-trial data, and suggest the need for new methods of validating data-constrained models for neural dynamics. © 2024 Neural information processing systems foundation. All rights reserved.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Measurement of the neutron capture cross sections of rhenium up to stellar s- and r-process temperatures at the China Spallation Neutron Source Back-n facility

引用

Physical Review Research 2024年第1期6卷 013225-013225页

作者： Gaole Yang Zhendong An Wei Jiang Xiankai Li Weiwei Qiu Zhengfa Liao Ziyue Zhuang Xiaoping Zhang Shengli Chen Chenchen Guo Erxi Xiao Xiao Fang Xinxiang Li Hongwei Wang Xinrong Hu Bing Jiang Wenqing Shen Jincheng Wang Jie Ren Xichao Ruan Dexin Wang Su-Yalatu Zhang Wen Luo Zhichao Zhu Haoyang Lan Zongwei Cao Xu Ma Yingdu Liu Pusen Wang Yi Yang Ping Su Xiangai Deng Wanbing He Yugang Ma Chunwang Ma Yuting Wang Zhitao Dai Ertao Li Pengqin He RenGuang Tang Tao Zhou Jing Wang Han Yi Yue Zhang Yonghao Chen Ruirui Fan Keqing Gao Qiang Li Kang Sun Zhixin Tan Minhao Gu Hantao Jing Jingyu Tang Institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China School of Physics and Astronomy Sun Yat-sen University Zhuhai 519082 China State Key Laboratory of Lunar and Planetary Sciences Macau University of Science and Technology Macau 999078 China CNSA Macau Center for Space Exploration and Science Macau 999078 China Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201800 China Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China Spallation Neutron Source Science Center Dongguan 523803 China School of Nuclear Science and Technology University of South China Hengyang 421001 China Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen University Zhuhai 519082 China University of Chinese Academy of Sciences Beijing 100049 China Shanghai Advanced Research Institute Chinese Academy of Sciences Shanghai 201210 China Key Laboratory of Nuclear Data China Institute of Atomic Energy Beijing 102413 China College of Mathematics and Physics Inner Mongolia Minzu University Tongliao 028000China Institute of Nuclear Physics Inner Mongolia Minzu University Tongliao 028000 China Shool of Materials Science and Engineering Xiangtan University Xiangtan 411100 China Key Laboratory of Nuclear Physics and Ion-beam Application (MOE) Institute of Modern Physics Department of Nuclear Science and Technology Fudan University Shanghai 200433 China Institute of Particle and Nuclear Physics Henan Normal University Xinxiang 453007 China School of Physics Henan Normal University Xinxiang 453007 China Shenzhen Center Cancer hospital Chinese Academy of Medical Sciences Shenzhen 518100 China Institute for Advanced Study in Nuclear Energy and Safety College of Physics and Optoelectronic Engineering Shenzhen University Shenzhen 518060 China School of Nuclear Science and Technology University of Science and Technology of China Hefei 230027 China

The neutron capture measurement of natural rhenium was performed with the time-of-flight technique at the Back-n facility of the China Spallation Neutron Source in the energy range from 1 to 500 eV of the resolved resonance region (RRR) and from 5 to 400 keV in the unresolved resonance region (URR). Prompt γ-rays originating from neutron-induced capture events were detected by four C6D6 detectors. The pulse height weighting technique and the double-bunch unfolding method based on the Bayesian theory were used in the data analysis. To obtain reliable measurement results, background subtraction, normalization, and corrections were carefully considered. The multilevel R-matrix Bayesian code SAMMY was used to extract the resonance parameters in the RRR. An absence of resonance near 392 eV is observed in our measurement, which has been observed in previous works. The average cross sections in the URR of natural rhenium relative to Au197 were obtained in logarithmical equidistant energy bins with 20 bins per energy decade. The talys code was used to describe the average cross sections in the URR; the Maxwellian-averaged cross sections (MACSs) of Re185 and Re187 are given from kT=5 to 100 keV. At a thermal energy of kT=30 keV, the MACS value for Re185 (1469±127 mb) is in good agreement with the Karlsruhe Astrophysical Database of Nucleosynthesis in Stars (KADoNIS) recommended value (1535±62 mb) within the error bars. By contrast, the value of 1361±118 mb for Re187 shows a discrepancy with the KADoNiS recommended value (1160±57 mb).

关键词： nuclear astrophysics nuclear reaction rates nuclear reactions Radiative capture Resonance reactions r process s process 150 ≤ A ≤ 189 nuclear data analysis & compilation

来源：评论

学校读者我要写书评

暂无评论

Ronchigram Simulation and Aberration Correction Training Using ***

引用

Microscopy Today 2022年第5期30卷 40-43页

作者： Sung, Suk Hyun Schnitzer, Noah Millsaps, William Kourkoutis, Lena F Hovden, Robert Department of Materials Science and Engineering University of Michigan Ann Arbor MI 48109 Department of Materials Science and Engineering Cornell University Ithaca NY 14853 Engineering Physics Program University of Michigan Ann Arbor MI 48109 School of Applied and Engineering Physics Cornell University Ithaca NY 14853 Kavli Institute at Cornell for Nanoscale Science Cornell University Ithaca NY 14853

This article introduces a training simulator for electron beam alignment using Ronchigrams. The interactive web application,***, is an advanced educational tool aimed at making scanning transmission electron microscopy (STEM) more accessible and open. For experienced microscopists, the tool offers on-hand quantification of simulated Ronchigrams and their resolution limits.

关键词： Ronchigram scanning transmission electron microscopy aberration correction image simulation software

来源：评论

学校读者我要写书评

暂无评论

Deep potentials for materials science

引用

Materials Futures 2022年第2期1卷 89-115页

作者： Tongqi Wen Linfeng Zhang Han Wang Weinan E David J Srolovitz Department of Mechanical Engineering The University of Hong KongHong KongHong Kong Special Administrative Region of China DP Technology BeijingPeople’s Republic of China AI for Science Institute BeijingPeople’s Republic of China Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsBeijingPeople’s Republic of China HEDPS CAPTCollege of EngineeringPeking UniversityBeijingPeople’s Republic of China School of Mathematical Sciences Peking UniversityBeijingPeople’s Republic of China Department of Mathematics and Program in Applied and Computational Mathematics Princeton UniversityPrincetonNJUnited States of America International Digital Economy Academy(IDEA) ShenzhenPeople’s Republic of China

To fill the gap between accurate(and expensive)ab initio calculations and efficient atomistic simulations based on empirical interatomic potentials,a new class of descriptions of atomic interactions has emerged and been widely applied;*** learning potentials(MLPs).One recently developed type of MLP is the deep potential(DP)*** this review,we provide an introduction to DP methods in computational materials *** theory underlying the DP method is presented along with a step-by-step introduction to their development and *** also review materials applications of DPs in a wide range of materials *** DP Library provides a platform for the development of DPs and a database of extant *** discuss the accuracy and efficiency of DPs compared with ab initio methods and empirical potentials.

关键词： deep potential atomistic simulation machine learning potential neural network

来源：评论

学校读者我要写书评

暂无评论

Determination of the cross section from 10 to 200 keV at the Back-n facility at CSNS

引用

The European Physical Journal A 2023年第10期59卷 1-11页

作者： Wang, Jincheng Ren, Jie Jiang, Wei Ruan, Xichao Sun, Qi Hu, Jifeng Jiang, Bing Bao, Jie Zhang, Qiwei Luan, Guangyuan Huang, Hanxiong Nie, Yangbo Ge, Zhigang An, Qi Bai, Haofan Bai, Jiangbo Cao, Ping Chen, Qiping Chen, Yonghao Chen, Zhen Cui, Zengqi Fan, Anchuan Fan, Ruirui Feng, Changqing Feng, Fanzhen Gao, Keqing Gu, Minhao Han, Changcai Han, Zijie He, Guozhu He, Yongcheng Hong, Yang Hu, Yiwei Jia, Weihua Jiang, Haoyu Jiang, Zhijie Jin, Zhengyao Kang, Ling Li, Bo Li, Chao Li, Gong Li, Jiawen Li, Qiang Li, Yang Liu, Jie Liu, Rong Liu, Shubin Ning, Changjun Qi, Binbin Ren, Zhizhou Song, Zhaohui Sun, Kang Tan, Zhixin Tang, Jingyu Tang, Shengda Wang, Lijiao Wang, Pengcheng Wang, Zhaohui Wen, Zhongwei Wu, Xiaoguang Wu, Xuan Xie, Likun Yang, Yiwei Yi, Han Yu, Yongji Zhang, Guohui Zhang, Linhao Zhang, Mohan Zhang, Xianpeng Zhang, Yuliang Zhang, Yue Zhang, Zhiyong Zhao, Maoyuan Zhou, Luping Zhu, Kejun Zhang, Jie Key Laboratory of Nuclear Data China Institute of Atomic Energy Beijing China Institute of High Energy Physics Chinese Academy of Sciences (CAS) Beijing China Spallation Neutron Source Science Center Dongguan China Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai China State Key Laboratory of Particle Detection and Electronics University of Science and Technology of China Hefei China Department of Modern Physics University of Science and Technology of China Hefei China State Key Laboratory of Nuclear Physics and Technology School of Physics Peking University Beijing China Institute of Nuclear Physics and Chemistry China Academy of Engineering Physics Mianyang China School of Nuclear Science and Technology University of Science and Technology of China Hefei China USTC Archaeometry Lab University of Science and Technology of China Hefei China State Key Laboratory of Particle Detection and Electronics Institute of High Energy Physics Chinese Academy of Sciences Beijing China Northwest Institute of Nuclear Technology Xi’an China University of Chinese Academy of Sciences Beijing China

The neutron capture cross section of $$^{232}Th$$ has been measured with the time-of-flight technique in the energy range from 10 to 200 keV at the back-streaming white neutron beam-line (Back-n) of China Spallation Neutron Source (CSNS). The pulse height weighting technique (PHWT) was applied with four C $$_{6}$$ D $$_{6}$$ liquid scintillators to measure the prompt gamma-ray energy release following neutron capture. The measurement data, corrected with the PHWT, have been normalized to the saturated resonances at 21.8 eV. The background was determined by a lead sample measurement and detailed Monte Carlo simulations. The $$^{232}Th(n,\gamma )$$ average cross sections have been determined relative to the $$^{197}Au(n,\gamma )$$ reaction cross sections. The results are consistent with the evaluation values of CENDL-3.2 and JENDL-5. The total uncertainties, including the PHWT, normalization, background subtraction, corrections, and relative measurement, are in the range of 4.5–4.8%.

关键词：

来源：评论

学校读者我要写书评

暂无评论

In situassessment of terrestrial gamma radiation dose and associated radiological hazards in Katsina State, Nigeria

引用

Isotopenpraxis Isotopes in Environmental and Health Studies 2023年第1期59卷 112-125页

作者： Nuraddeen Nasiru Garba Mukhtar Abdulkadir Rabiu Nasiru Muneer Aziz Saleh Suleiman Bello Mayeen Uddin Khandaker Che Azurahanim Che Abdullah Usman Musa Kankara a Department of Physics Ahmadu Bello University Zaria Nigeria a Department of Physics Ahmadu Bello University Zaria Nigeriab Department of Physics Isa Kaita College of Education Katsina State Nigeria c Nuclear Engineering Programme School of Chemical and Energy Engineering Faculty of Engineering Universiti Teknologi Malaysia Johore Bahru Malaysiad National Atomic Energy Commission (NATEC) Sana’a Yemen e Department of Physics Umaru Musa Yar’adua University Katsina Nigeria f Centre for Applied Physics and Radiation Technologies School of Engineering and Technology Sunway University Selangor Malaysia g Material Synthesis and Characterization Laboratory Institute of Advanced Technology (ITMA) University Putra Malaysia Selangor Malaysiah Department of Physics Faculty of Science University Putra Malaysia Selangor Malaysia

ABSTRACTABSTRACTTerrestrial gamma radiation dose (TGRD) rates were measuredin situfrom different locations in Katsina State, Nigeria, using a portable radiation survey metre based on geological formations and soil types. The measured TGRD rates ranged from 45 to 271 nGyh–1with an average value of 116 ± 1 nGyh–1. Geological formation (silicified sheared rock) and soil type (lithosols and ferruginous crusts and ferruginous tropical soils) appeared to have the highest mean TGRD values of 163 and 134 nGyh–1with sandstone geological formation and alluvial and hydromorphic soils having the lowest TGRD with values of 80 and 61 nGyh–1, respectively. One way ANOVA results shows that the tested null hypothesis was rejected. Thus, indicating that there exists a strong relationship between the various geological formations, soil types with the measured TGRD values based on the alternate hypothesis. Human health hazard indices like annual effective dose equivalent (AEDE), lifetime outdoor annual equivalent dose, and relative excess lifetime outdoor cancer risk associated with the mean TGRD of the study area were also calculated and found to be 0.711, 9.955 mSv, and 5.79 × 10–4, respectively. These values were higher than the world average values but favourable compared with the safety limits recommended by ICRP.

关键词： Cancer risk gamma radiation geological formation human health natural radioactivity Nigeria radionuclides soil types

来源：评论

学校读者我要写书评

暂无评论

Gallium Oxide as Photonic Integrated Platforms in the UV-Visible Spectra

Gallium Oxide as Photonic Integrated Platforms in the UV-Vis...

引用

2023 Conference on Lasers and Electro-Optics, CLEO 2023

作者： Zhou, Jingan Zhao, Xuan Xu, Rui Zhang, Xiang Fu, Kai Li, Tao Xu, Mingfei Luo, Shisong He, Ziyi Robinson, Jacob T. Zhu, Hanyu Ajayan, Pulickel M. Zhang, Xiaodong Zhao, Yuji Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Materials Science and NanoEngineering Rice University HoustonTX77005 United States School of Electrical Computer and Energy Engineering Arizona State University TempeAZ85287 United States Nanofabrication facility Suzhou Institute of Nano-Tech and Nano-Bionics Chinese Academy of Sciences Jiangsu Suzhou215123 China

We report the Ga2O3 as photonic integrated platforms and its nonlinear optical effects in the UV-visible spectra. A low propagation loss of 3.7 dB/cm and second-order susceptibility of x(2)=4.89xl03pm/V were obtained.... 详细信息

ISBN: (纸本)9781957171258

关键词： Gallium compounds

来源：评论

学校读者我要写书评

暂无评论

engineering dimensionality of collective dipole-dipole interactions using a nanophotonic environment

Engineering dimensionality of collective dipole-dipole inter...

引用

Conference on Lasers and Electro-Optics (CLEO)

作者： Ashwin K. Boddeti Yi Wang Xitlali Juarez Alexandra Boltasseva Hadiseh Alaeian Teri W. Odom Zubin Jacob Elmore Family School of Electrical and Computer Engineering and Birck Nanotechnology Center Purdue University West Lafayette Indiana USA Graduate Program in Applied Physics Northwestern University Evanston IL USA Department of Materials Science and Engineering Northwestern University Evanston Illinois USA Department of Chemistry and Department of Materials Science and Engineering Northwestern University Evanston Illinois USA

We experimentally demonstrate reduced dimensionality in a interacting ensemble of emitters. The well-known stretched exponential decay dynamics, I(t)/I 0 = exp(−γ D t)exp(−αt β ) with β = 0.5 in 3D geometries, is... 详细信息

ISBN: (纸本)9781957171258

关键词： Energy transfer Fluorescence Molecules Spontaneous emission Titanium dioxide

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：