检索结果-南通市图书馆

A simulation study on spatial and time resolution for a cost-effective positron emission particle tracking system

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Particuology 2024年第5期88卷 312-322页

作者： Josephine Oppotsch Matthias Steinke Miriam Fritsch Fritz-Herbert Heinsius Thomas Held Nikoline Hilse Viktor Scherer Ulrich Wiedner Ruhr-Universität Bochum Institut für Experimentalphysik I44801 BochumGermany Ruhr-Universität Bochum Lehrstuhl für Energieanlagen und Energieprozesstechnik44801 BochumGermany

This work is the second part of a simulation study investigating the processing of densely packed and moving granular assemblies by positron emission particle tracking (PEPT).Since medical positron emission tomography (PET) scanners commonly used for PEPT are very expensive,a PET-like detector system based on cost-effective organic plastic scintillator bars is being developed and tested for its capabilities.In this context,the spatial resolution of a resting positron source,a source moving on a freely designed model path,and a particle motion given by a discrete element method (DEM) simulation is studied using Monte Carlo simulations and the software toolkit Geant4.This not only extended the simulation and reconstruction to a moving source but also significantly improved the spatial resolution compared to previous work by adding oversampling and iteration to the reconstruction algorithm.furthermore,in the case of a source following a trajectory developed from DEM simulations,a very good resolution of about 1 mm in all three directions and an average 3D deviation between simulated and reconstructed events of 2.3 mm could be determined.Thus,the resolution for realistic particle motion within the generic grate system (which is the test rig for further experimental studies) is well below the smallest particle size.The simulation of the dependence of the reconstruction accuracy on tracer particle location revealed a nearly constant efficiency within the entire detector system,which demonstrates that boundary effects can be neglected.

关键词： Positron emission particle tracking Monte Carlo method Time-of-flight Plastic scintillators Silicon photomultipliers(SiPMs)

Database system for managing 20,00020-inch PMTs at JUNO

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2022年第3期33卷 10-21页

作者： Jun Wang Nikolay Anfimov Jing-Yuan Guo Yu Gu Hang Hu Min Li Qiu-Mei Ma Alexander Olshevskiy Zhao-Yuan Peng Zhong-Hua Qin Alexander Tietzsch Bjorn Wonsak Wei Wang Zhi-Min Wang Mei-Hang Xu Wan Xie Zheng-Yun You Hai-Qiong Zhang Rong Zhao School of Physics Sun Yat-Sen UniversityGuangzhou 510275China Joint institute for Nuclear Research Dubna 141980Russia College of Science and Engineering Ji Nan UniversityGuangzhou 510632China institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Particle Detection and Electronics Beijing 100049China Physikalisches institut Eberhard Karls Universitat Tubingen72074 TubingenGermany institut fur experimentalphysik Universitat Hamburg20148 HamburgGermany Sino-French institute of Nuclear Engineering and Technology Sun Yat-Sen UniversityZhuhai 519082China

A database system,known as the large PMT characterization and instrumentation database system(LPMT-CIDS),was designed and implemented for the Jiangmen Underground Neutrino Observatory(JUNO).The system is based on a Linux+Apache+MySQL+PHP(LAMP)server and focuses on modularization and architecture separation.It covers all the testing stages for the 20-inch photomultiplier tubes(PMTs)at JUNO and provides its users with data storage,analysis,and visualization services.Based on the successful use of the system in the 20-inch PMT testing program,its design approach and construction elements can be extended to other projects.

关键词： LAMP Photomultiplier tubes Jiangmen underground neutrino observatory Data visualization

Experimental investigation of the normal spectral emissivity and other thermophysical properties of pulse-heated Ni-Ti and Au-Ni alloys into the liquid phase

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2006年第5期25卷 592-596页

作者： B.Wilthan G.Pottlacher institut für experimentalphysik Technische Universitt GrazPetersgasse 168010 GrazAustria

In a previous paper it was shown that the normal spectral emissivity at 684.5 nm of a binary alloy can be lower than that of the pure constituent components. For the actual probes it was found that the observed values of normal spectral emissivity of the alloys are in between or higher than those of the pure constituent components. Experiments were conducted on the alloy systems Ni-Ti and Au-Ni. Their emissivity as well as electrical resistivity and enthalpy as a function of temperature is presented.

关键词： normal spectral emissivity thermophysical properties resistivity enthalpy pulse-heating Ni-Ti alloy Au-Ni alloy liquid phase

Raman Scattering Study of ND_(4)^(+)-Ion Motion and Structural Phase Transitions in(ND_(4))_(2)PbCl_(6)

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 1996年第5期13卷 394-396页

作者： SHI Jin-rong XU Yong-chen Y.Kume B.Arnscheidt J.Pelzl WU Xiang Pohl institute of Solid State Physics Tongji UniversityShanghai 200092 Faculty of General Education Azabu UniversityFuchinobeSagatniharaKanagazva 229Japan institut fur experimentalphysikⅢ AG Festkorperspektroskopie y Ruhr-Universitat Bochum44780 BochumGermany International Center for Materials Physics Chinese Academy of SciencesShenyany 110015

Rams spectra of the internal modes of ND^(+)_(4)-ion in (ND_(4))_(2)PbCl_(6) crystal have been recorded in the temperature range of 5-300 K.A new structural phase tratisition was observed at 34 K be-ca-use of deuterium effect.Discontinuous behaviours of the internal modes of the ND 4-ion at this temperature show that the structural transition is one of first order.

关键词： effect. (4) Transition

Afterpulse measurement of JUNO 20‑inch PMTs

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2023年第1期34卷 136-145页

作者： Rong Zhao Nikolay Anfimov Yu Chen Hang Hu Jun Hu Xiao‑Lu Ji Denis Korablev Min Li Alexander Olshevskiy Zhao‑Yuan Peng Arseny Rybnikov Zhong‑Hua Qin Jun Wang Wei Wang Zhi‑Min Wang Björn Wonsak School of Physics Sun Yat-sen UniversityGuangzhou 510275China Joint institute for Nuclear Research Dubna 141980Russia institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Particle Detection and Electronics Beijing 100049China Sino‑French institute of Nuclear Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China State Key Laboratory of Particle Detection and Electronic Beijing 100049China institut für experimentalphysik Universität HamburgHamburg 20148Germany

In this study,we present the large photomultiplier tube(PMT)afterpulse measurement results obtained from the Jiangmen underground neutrino observatory(JUNO)experiment.A total of 11 dynode-PMTs(R12860)from the Hamamatsu company(Hamamatsu Photonics K.K.(HPK))and 150 micro-channel plate PMTs(MCP-PMTs,GDB-6201)from the NNVT company(North Night Vision Technology Co.,Ltd.(NNVT))were tested.Subsequently,an afterpulse model was built according to the afterpulse time distribution and the probability of occurrence for these two types of PMTs.The average ratio of the total afterpulse charge with a delay between 0.5μs and 20μs to the primary pulse charge is∼5.7%(13.2%)for the tested MCPPMTs(dynode-PMTs).The JUNO experiment will deploy 20,01220-inch PMTs;this study will benefit detector simulation,event reconstruction,and data analysis regarding the JUNO experiment.

关键词： Afterpulse MCP-PMT JUNO Dynode-PMT 20-inch PMT

Variation of the Observed Widths of La I Lines with the Energy of the Upper Excited Levels, Demonstrated on Previously Unknown Energy Levels

在线全文

学校读者我要写书评

暂无评论

Spectral Analysis Review 2016年第3期4卷 23-40页

作者： L. Windholz B. Gamper T. Binder institut für experimentalphysik Technische Universit&auml t Graz Graz Austria

We performed systematic laser spectroscopic investigations of La I spectral lines, using optogalvanic detection. Sixteen previously unknown even parity levels, having energies between 40,300 and 44,300 cm-1, are reported. These levels classify altogether 67 lines, not listed in spectral tables. The new levels were found due to the observation of the depopulation of the lower levels of the excited transitions. We found a remarkable variation of the observed widths of single hyperfine structure components dependent on the energy of the upper excited levels. Some levels having energies higher than 43,000 cm-1 appear to have a very high ionization probability.

关键词： New Energy Levels of Lanthanum I Hyperfine Structure Line Widths

Research Article Local structure and magnetic properties of a nanocrystalline Mnrich Cantor alloy thin film down to the atomic scale

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2023年第4期16卷 5626-5639页

作者： Alevtina Smekhova Alexei Kuzmin Konrad Siemensmeyer Chen Luo James Taylor Sangeeta Thakur Florin Radu Eugen Weschke Ana Guilherme Buzanich Bin Xiao Alan Savan Kirill V.Yusenko Alfred Ludwig Helmholtz-Zentrum Berlin für Materialien und Energie(HZB) Berlin D-12489Germany institute of Solid State Physics University of LatviaRiga LV-1063Latvia Physik-Department Technische Universität MünchenGarching D-85748Germany institut für experimentalphysik Freie Universität BerlinBerlin 14195Germany Bundesanstalt für Materialforschung und-prüfung(BAM) Berlin D-12489Germany institut für Werkstoffe Ruhr-Universität BochumBochum D-44801Germany

The huge atomic heterogeneity of high-entropy materials along with a possibility to unravel the behavior of individual components at the atomic scale suggests a great promise in designing new compositionally complex systems with the desired multifunctionality.Herein,we apply multi-edge X-ray absorption spectroscopy(extended X-ray absorption fine structure(EXAFS),Xray absorption near edge structure(XANES),and X-ray magnetic circular dichroism(XMCD))to probe the structural,electronic,and magnetic properties of all individual constituents in the single-phase face-centered cubic(fcc)-structured nanocrystalline thin film of Cr_(20)Mn_(26)Fe_(18)Co_(19)Ni_(17)(at.%)high-entropy alloy on the local scale.The local crystallographic ordering and componentdependent lattice displacements were explored within the reverse Monte Carlo approach applied to EXAFS spectra collected at the K absorption edges of several constituents at room temperature.A homogeneous short-range fcc atomic environment around the absorbers of each type with very similar statistically averaged interatomic distances(2.54-2.55Å)to their nearest-neighbors and enlarged structural relaxations of Cr atoms were revealed.XANES and XMCD spectra collected at the L2,3 absorption edges of all principal components at low temperature from the oxidized and in situ cleaned surfaces were used to probe the oxidation states,the changes in the electronic structure,and magnetic behavior of all constituents at the surface and in the sub-surface volume of the film.The spin and orbital magnetic moments of Fe,Co,and Ni components were quantitatively evaluated.The presence of magnetic phase transitions and the co-existence of different magnetic phases were uncovered by conventional magnetometry in a broad temperature range.

关键词： high-entropy alloys reverse Monte Carlo(RMC) element-specific spectroscopy extended X-ray absorption fine structure(EXAFS) X-ray magnetic circular dichroism(XMCD) magnetism

MAGNETIC PROPERTIES OF HEAT TREATED Nd_(3)Fe_(81)B_(16) ALLOY

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 1989年第5期6卷 221-224页

作者：顾本喜翟宏如沈保根 S.Methfessel Department of Physics Nanjing UniversityNanjing institute of Physics Academia SinicaBeijing institut fiir experimentalphysik IV Ruhr-UniversitatBochumWest Germany

The hysteresis loop and Mdssbauer spectrum of the heat treated Nd_(3)Fe_(81)B_(16) alloy ribbons annealing at 660℃ for lOmin.have been measured.A coercive field of about 2kOe and an energy product of about 8MGOe are obtained at room temperature.X-ray diffraction and Mdssbauer spectrum analyses show that the high coercivity may originate from the Fe_(3)B phase containing Nd.The value of remanence and energy product in this alloy are much higher than those of anisotropic BaFe_(12)O_(19) ferrite.It may be used as a cheap permanent magnet.

关键词： temperature alloy

GdPO_4∶Eu^(3+)和GdBO_3∶Eu^(3+)中“Gd-Eu”间的能量传递

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国稀土学报 2005年第4期23卷 429-433页

作者：陈永虎刘波施朝淑 Zimmerer G 中国科学技术大学物理系安徽合肥230026 institut für experimentalphysik der Universitt Hamburg

利用同步辐射光源(德国HASYLAB实验室的SUPERLUMI实验站)对高温固相法制备的GdPO4∶Eu3+和GdBO3∶Eu3+的发射谱与激发谱进行了研究,并从量子剪裁的角度对“Gd3+-Eu3+”之间的能量传递作了讨论。在两种样品监测Eu3+红光发射的激发谱上,... 详细信息

利用同步辐射光源(德国HASYLAB实验室的SUPERLUMI实验站)对高温固相法制备的GdPO4∶Eu3+和GdBO3∶Eu3+的发射谱与激发谱进行了研究,并从量子剪裁的角度对“Gd3+-Eu3+”之间的能量传递作了讨论。在两种样品监测Eu3+红光发射的激发谱上,都显著观察到了对应Gd3+离子4f-4f跃迁的谱线,说明从基质中Gd3+离子向掺杂的Eu3+离子之间存在非常有效的能量传递,这有利于量子剪裁的发生。在激发谱上还观察到了对应Eu3+-O2-电荷迁移态的宽激发带(180~270nm),而对应Gd3+离子8S7/2→6GJ跃迁的谱线(196nm,203nm)叠加在这个宽带之上,微弱可辨,这不利于Gd3+-Eu3+间交叉弛豫的能量传递过程,从而不利于量子剪裁的发生。结合Eu3+-O2-电荷迁移态位置变化的规律,提出了如何避开其干扰以增强量子剪裁效应的材料设计方案。

关键词：发光材料量子剪裁真空紫外(VUV) 电荷迁移态(CTS) GdPO4∶Eu3+ GdBO3∶Eu3+ 稀土