检索结果-南通市图书馆

Point spread functions for a small gamma camera with pinhole collimator

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2003年第3期14卷 195-198页

作者： LIU Shi-Tao, xu zi-zong, WANG Zhao-Min, xu Shen-Bo (Department of Modern Physics, University of Science and Technology of China, Hefei 230027) Department of Modern Physics University of Science and Technology of China Hefei 230027

A set of point spread functions (PSF) has been obtained by means of Monte-Carlo simulation for asmall gamma camera with a pinhole collimator of various hole diameters. The FOV (field of view) of the camera isexpended from 45 mm to 70 mm in diameter. The position dependence of the variances of PSF is presented, and theacceptance for the 140 kev gamma rays is explored. A phantom of 70 mm in diameter was experimentally imaged inthe camera with effective FOV of only 45 mm in diameter.

关键词：点扩散函数 γ照相机针孔准直器 PSF Monte-Carlo仿真临床诊断

Scintillation Characteristics of Doped PbWO4 Crystals

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2001年第4期18卷 513-515页

作者： SHAO Ming CHEN Hong-Fang LI Cheng xu Tong SHI Chao-Shu WU Jian CHEN Hui xu zi-zong WANG Zhao-Min WANG Xiao-Lian DENG Qun YIN Zhi-Wen Department of Modern Physics University of Science and Technology of ChinaHefei 230027 Shanghai Institute of Ceramics Chinese Academy of SciencesShanghai 200050

Emission spectra,longitudinal transmission and light output for the Sb-doped and Y-doped PbWO_(4) crystals are *** decay kinetics has been measured by using gate integration and single photon counting method with blue and green *** hardness has also been measured by using ^(60)Coγ-ray irradiation under different dose rates and different dose rate *** light yield and radiation hardness of the Sb-doped and Y-doped PbWO_(4) crystals are improved as compared to the undoped crystals and are suitable for the requirements of compact muon solenoid.

关键词： PbWO4 Scintillation kinetics

Study of performance of small gamma camera consisting of crystal pixel array and position sensitive photomultiplier tube

维普期刊数据库评论

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 2005年第4期16卷 238-243页

作者： ZHU Jie LIU Shi-Tao LEI Xiao-Wen YAN Tian-Xin xu zi-zong WANG Zhao-Min Department of Modern Physics University of Science and Technology of China Hefei 230026

The performance of gamma camera with NaI(Tl) array coupled with position sensitive photomultiplier tube (PSPMT) R2486 has been studied. The pixel size of NaI(Tl) crystal is 2mm×2mm and the overall dimension of the array is 48.2mm×48.2mm×5mm. There are 484 pixels in a 22×22 matrix. Because each pixel can produce a much focused light spot and restrict the spread of photons, position resolution of the gamma camera is mainly determined by pixel size. It is shown that crystal array pixel can reduce shrinkage effect and improve intrinsic position resolution greatly via restricting the spread of photons. Experimental results demonstrate that its position resolution and linearity are much improved comparing with the gamma camera using planar crystals coupled with PSPMT.

关键词：光电倍增器像素照相机 PSPMT 线性关系

在线全文

学校读者我要写书评

暂无评论

辐射消毒用电子束剂量场的研究

核电子学与探测技术 2005年第6期25卷 897-900,886页

作者：王全伍建许咨宗中国科学技术大学近代物理系安徽合肥230026

通过模拟跟踪2、3MeV电子在1cm纸层中的相互作用过程,记录统计电子及其辐射次级粒子在纸层及其周围环境的能量沉积。在假定病毒的致死当量剂量为200Sv的情况下,计算离束靶不同距离的水介质(水模)的当量剂量。还给出了采用电子束扫描传... 详细信息

通过模拟跟踪2、3MeV电子在1cm纸层中的相互作用过程,记录统计电子及其辐射次级粒子在纸层及其周围环境的能量沉积。在假定病毒的致死当量剂量为200Sv的情况下,计算离束靶不同距离的水介质(水模)的当量剂量。还给出了采用电子束扫描传输带上的信件的方式,不同处理信件速率对加速器电子束平均流强的要求。例如,要处理1t／h信件,要求2、3MeV电子束流强为29、22μA。

关键词：电子束致死剂量剂量分布

Realizing high initial Coulombic efficiency in manganese-based layered oxide cathodes for sodium-ion batteries via P2/O'3 biphasic structure optimization

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2024年第5期43卷 2093-2102页

作者： Bo Peng zi-Hao Zhou Ping xuan Jie xu Lian-Bo Ma School of Materials Science and Engineering Anhui University ofTechnologyMa'anshan 243002China Anhui Product Quality Supervision&Inspection Research Institute Hefei 230051China

Mn-based layered oxides are among the most promising cathode materials for sodium-ion batteries owing to the advantages of abundance,environmenta friendliness,low cost and high specific capacity.P2 and O'3 are two representative structures of Mn-based layered ***,the P2 structure containing insufficien Na generally exhibits low initial charge capacity,while O'3structure with sufficient Na delivers high initial charge capacity but poor cycle *** study prepared a multitude of Na_(x)MnO_(2)(x=0.7,0.8,0.9)cathode materials with varying P2/O'3 ratios and further investigated their electrochemical *** optimized Na_(0.8)MnO_(2) comprising 69.9 wt%O'3 and 30.1 wt%P2 phase,exhibited relatively balanced specific capacity,Coulombic efficiency and cycle ***,it achieved a high specific capacity of 128.9 mAh·g^(-1) with an initia Coulombic efficiency of 98.2%in half-cell configuration The Na_(0.8)MnO_(2)//hard carbon full cell also achieved a high specific capacity of 126.7 mAh·g^(-1) with an initia Coulombic efficiency of 98.9%.Moreover,the capacity fading mechanism was revealed by combining in-situ and ex-situ X-ray *** findings of this study provide theoretical guidance for further modification design of Mnbased layered cathodes.

关键词： Sodium-ion batteries Cathode materials Mn-based layered oxides P2/0'3 composites

Chain Dynamics Heterogeneity in Plasticized Poly(vinyl butyral)(PVB) as Elucidated by Solid-State NMR

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2024年第1期42卷 113-124,I0010页

作者： Jing Lv xu Chen zi-Shuo Wu Ya-Hui Li Wei Chen National Synchrotron Radiation Laboratory Anhui Provincial Engineering Laboratory of Advanced Functional Polymer FilmCAS Key Laboratory of Soft Matter ChemistryUniversity of Scienceand Technology of ChinaHefei 230026China

The chain dynamics heterogeneity of the poly(vinyl butyral)(PVB) plasticized by triethylene glycol bis(2-ethylhexa noate)(TEG-EH) was investigated by various solid-state NMR *** plasticized PVB shows two domains in distinct molecular dynamics differences,namely,rigid and soft domains,where the latter is the plasticizer-rich *** time domain low field NMR was first used to investigate the dynamics heterogeneity of the plasticized PVB,and the results show the decreasing activated energy of components in the soft domain of plasticized PVB(E_a=20.2 kJ/mol) as compared with that of the pristine one(E_a=24.3 kJ/mol).Detailed dynamics heterogeneity was obtained by high-field NMR with site-specific *** quadrupole-echo ~2H-NMR was adopted to elucidate the dynamics heterogeneity of the vinyl alcohol(VA) units,where only the hydroxyl group of VA is *** ~1H-^(13)C WISE NMR spectra show that there is not much difference in the mobility of the VB unit in PVB with and without plasticizer,whereas the glass transition temperature differed by approximately 53℃.This is further supported by Torchia's T_1 relaxation *** origin of such an unusual phenomenon is attributed to the critical role of the remaining VA(~22%) in the soft domain,where the VA units locally aggregate through hydrogen ***,the existence of a mobility gradient in the VB unit has been ***,the mobility difference for VB with different stereo-geometry(meso or racemic conformation) is observed for the first *** indicates the importance of modulating the ratio of meso over racemic VB for controlling the macroscopic perfo rmance of PVB.

关键词： Poly(vinyl butyral) Dynamics heterogeneity Plasticizer Solid state NMR

A review of solid-state lithium metal batteries through in-situ solidification

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第1期67卷 67-86页

作者： Pan xu zong-Yao Shuang Chen-zi Zhao xue Li Li-Zhen Fan Aibing Chen Haoting Chen Elena Kuzmina Elena Karaseva Vladimir Kolosnitsyn Xiaoyuan Zeng Peng Dong Yingjie Zhang Mingpei Wang Qiang Zhang Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology Department of Chemical EngineeringTsinghua UniversityBeijing 100084China National and Local Joint Engineering Laboratory for Lithium-ion Batteries and Materials Preparation Technology Key Laboratory of Advanced Battery Materials of Yunnan ProvinceFaculty of Metallurgical and Energy EngineeringKunming University of Science and TechnologyKunming 650093China Institute of Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China College of Chemical and Pharmaceutical Engineering Hebei University of Science and TechnologyShijiazhuang 050018China Ordos Carbon Neutral Research and Application Co. Ltd.Ordos City 017010China Ufa Institute of Chemistry UFRC RAS Ufa 450054Russia Institute for Carbon Neutrality Tsinghua UniversityBeijing 100084China Shanxi Research Institute for Clean Energy Tsinghua UniversityTaiyuan 030032China

High-energy-density lithium metal batteries are the next-generation battery systems of choice,and replacing the flammable liquid electrolyte with a polymer solid-state electrolyte is a prominent conduct towards realizing the goal of high-safety and high-specific-energy ***,the inherent intractable problems of poor solid-solid contacts between the electrode/electrolyte and the growth of Li dendrites hinder their practical *** in-situ solidification has demonstrated a variety of advantages in the application of polymer electrolytes and artificial interphase,including the design of integrated polymer electrolytes and asymmetric polymer electrolytes to enhance the compatibility of solid–solid contact and compatibility between various electrolytes,and the construction of artificial interphase between the Li anode and cathode to suppress the formation of Li dendrites and to enhance the high-voltage stability of polymer *** review firstly elaborates the history of in-situ solidification for solid-state batteries,and then focuses on the synthetic methods of solidified ***,the recent progress of in-situ solidification technology from both the design of polymer electrolytes and the construction of artificial interphase is summarized,and the importance of in-situ solidification technology in enhancing safety is ***,prospects,emerging challenges,and practical applications of in-situ solidification are envisioned.

关键词： in-situ solidification polymer electrolyte artificial solid electrolyte interphase rechargeable lithium metal batteries dendrite-free lithium metal anode

A high dynamic range readout unit for a calorimeter

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2012年第1期36卷 71-73页

作者： ZHANG Yun-Long LI Bing FENG Chang-Qing LI Xian-Li WANG Xiao-Lian xu zi-zong GUO Jian-Hua CAI Ming-sheng HU Yi-Ming WU Jian CHANG Jin Department of Modern Physics University of Science and Technology of ChinaHefei 230026China Purple Mountain Observatory Nanjing 210008China

A high dynamic range readout system,consisting of a multi-dynode readout PMT and a VA32 chip,is *** LED system is set up to calibrate the relative gains between the dynodes,and the ADC counts per MIPs from dynode 7 ar... 详细信息

关键词： BGO calorimeter VA32 chip PMT LED high dynamic readout

Design of a large momentum acceptance proton therapy gantry utilizing AG-CCT magnets

在线全文

学校读者我要写书评

暂无评论

NUCLEAR SCIENCE AND TECHNIQUES 2024年第10期35卷 1-11页

作者： Liao, Yi-Cheng Liu, xu Wang, Wei Yang, zi-Yi Chen, Qu-Shan Qin, Bin Huazhong Univ Sci & Technol State Key Lab Adv Electromagnet Technol Wuhan 430074 Peoples R China

The application of superconducting (SC) technology enables magnets to excite strong fields with small footprints, which has great potential for miniaturizing proton therapy gantries. However, the slow ramping rate of SC magnets results in a low treatment efficiency compared with normal-conducting (NC) gantries. To address this problem, this study proposes a compact proton therapy gantry design with a large momentum acceptance utilizing alternating-gradient canted-cosine-theta (AG-CCT) SC magnets. In our design, a high-transmission degrader is mounted in the middle of the gantry, and the upstream beamline employs NC magnets with small apertures. Downstream of the degrader, large-bore AG-CCT magnets with strong alternating focusing gradients are set symmetrically as a local achromat, which realizes a momentum acceptance of 20% (or 40% in the energy domain). Therefore, only three magnetic working points are required to cover a treatment energy of 70-230 MeV. Owing to the large momentum acceptance, the proton beam after the degrader can be directly delivered to the isocenter without truncating its energy spectrum, which can significantly increase the treatment efficiency but causes severe dispersion effects during pencil beam scanning. Therefore, a compensation method was introduced by tuning the normal and skewed quadrupoles during the scanning process. As a result, the new gantry not only presents a remarkable reduction in the size and weight of the facility but also shows good potential for fast treatment.

关键词： Alternating-gradient canted-cosine-theta magnets Large momentum acceptance gantry Pencil beam scanning Proton therapy ENERGY DEGRADER BEAM OPTICS OPTIMIZATION