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Enhanced quantitative X-ray phase-contrast images using Foucault differential filters

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Chinese Optics Letters 2017年第8期15卷 44-47页

作者： Jaeho Choi Young-Sung Park department of physics Dankook University Division of RI Convergence Research Korea Institute of Radiological and Medical Sciences

Several X-ray phase visualization methods are being real- ized for imaging of phase objects, such as biological and polymeric specimens. Grating-based phase-contrast imaging using a source-grating-attached X-ray tube ... 详细信息

关键词： real Enhanced quantitative X-ray phase-contrast images using Foucault differential filters FDF

Temperature-dependent synergistic evolution mechanism of rhenium and irradiation defects in tungsten-rhenium alloys

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Journal of Materials Science & Technology 2023年第14期145卷 221-234页

作者： Yu-Hao Li Fang-Ya Yue Zhong-Zhu Li Peng-Wei Hou Yu-Ze Niu Hui-Zhi Ma Ying Zhang Xun-Xiang Hu Hui-Qiu Deng Hong-Bo Zhou Fei Gao Guang-Hong Lu department of physics Beihang UniversityBeijing 100191China Beijing Key Laboratory of Advanced Nuclear Materials and physics Beihang UniversityBeijing 100191China College of physics Sichuan UniversityChengdu 610065China School of physics and Electronics Hunan UniversityChangsha 410082China department of Nuclear Engineering and radiological Science University of MichiganAnn ArborMI 48109USA

We have systemically investigated the synergistic evolution of rhenium(Re)and irradiation defects in tungsten(W)-Re alloys under different temperatures and irradiation doses using object Kinetic Monte Carlo method.Our results revealed the underlying mechanism for the transition of Re effect on W from beneficial to harmful during the Re-defects evolution with the increase of irradiation dose,in which tem-perature always plays a critical role.On the one hand,Re will significantly promote the defect annihila-tion at low irradiation doses and high temperatures,thereby effectively reducing their sizes and number densities.This is due to the formation of stable Re-SIAs complexes that can be eliminated by the mobile vacancy-type defects,whereas the transition of the migration pattern of SIAs only plays a weak role in the defect recombination in W-Re system.On the other hand,with the increase of irradiation dose,Re will aggregate to form Re-rich clusters or even precipitates.Interestingly,the formation mechanism of Re-rich clusters is also dependent on temperature.At low temperatures,the interstitial-mediated mech-anism plays a crucial role in the Re-rich cluster formation,while at high temperatures,both SIA-type and vacancy-type defects will act as the transport carriers of Re to promote their clustering.Accordingly,the critical conditions for the transition of Re from beneficial to harmful and the formation of Re-rich clusters at different tem peratures and irradiation doses are given with the help of the phase diagram.Our work presents the temperature dependence of the synergy of Re and irradiation defects in W-Re in fusion-relevant environment,which provides a good reference for the development of radiation-resistant materials and the prediction of W performance in fusion reactors.

关键词： Synergistic evolution Irradiation defects Defects recombination Rhenium-rich clusters Tungsten-rhenium alloys

Anisotropic Migration of Defects under Strain Effect in BCC Iron

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Chinese physics Letters 2017年第7期34卷 164-167页

作者：高宁高飞王志光 Laboratory of Advanced Nuclear Material Institute of Modern PhysicsLanzhou department of Nuclear Engineering and radiological Sciences University of Michigan

The basic properties of defects （self-interstitial and vacancy） in/3CC iron under uniaxial tensile strain are investi- gated with atomic simulation methods. The formation and migration energies of them show different dependences on the directions of uniaxial tensile strain in two different computation boxes. In box-1, the uniaxial tensile strain a/ong the （1005 direction influences the formation and migration energies of the （1105 dumbbell but slightly affects the migration energy of a single vacancy. In box-2, the uniaxial tensile strain along the 〈111〉 direction influences the formation and migration energies of both vacancy and interstitials. Especially, a 〈110〉 dumbbell has a lower migration energy when its migration direction is the same or close to the strain direction, while along these directions, a vacancy has a higher migration energy. Aft these results indicate that the uniaxial tensile strain can result in the anisotropic formation and migration energies of simple defects in materials.

关键词： der BCC 110

Li3PO4:M(M=Tb,Cu)phosphors for radiation dosimetry

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Rare Metals 2017年第9期36卷 758-763页

作者： Chetan B.Palan Nikhilesh Bajaj Anuj Soni Mukund Kulkarni Shreeniwas Omanwar department of physics Sant Gadge Baba Amravati University Amravati 444602India department of physics Toshniwal ACS CollegeSengaonHingoli 431542India radiological physics and Advisory Division Bhabha Atomic Research CentreMumbai 400094India

The dosimetric phosphors Li3PO4：M（M=Tb, Cu） were produced by modified solid-state method.The structural and morphological characterization was carried out through X-ray diffraction（XRD） and scanning electron microscope（SEM）. Additionally, the photoluminescence（PL）, thermoluminescence（TL） and optically stimulated luminescence（OSL） properties of powder Li3PO4 doped with Tb and Cu were studied. It is advocated that Li3PO4： Cu phosphor not only shows higher OSL sensitivity（25 times or more） but also gives faster decay in OSL signals than that of Li3PO4： Tb^（3＋） phosphor. The minimum detectable dose（MDD） of Li3PO4：M（M=Tb,Cu） phosphors is found to be 21.69 × 10^（-3） and 3.33 ×10^（-6） J·kg^（-1）,respectively. In OSL mode, phosphor shows linear dose response in the range of 0.02-20.00 J·kg^（-1）.In TL mode, sensitivity of Li3PO4： Cu phosphor is more than that of Li3PO4： Tb phosphor. The kinetics parameters such as activation energy and frequency factors were determined by peak shape method, and photoionization cross sections of prepared phosphor were calculated.

关键词： Optically stimulated luminescence Radiationdosimetry Modified solid-state method Minimumdetectable dose

Optical and structural properties of Ge-ion-implanted fused silica after annealing in different ambient conditions

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Chinese physics B 2010年第1期19卷 551-556页

作者：向霞陈猛陈美艳祖小涛朱莎王鲁闽 department of Applied physics University of Electronic Science and Technology of China department of Nuclear Engineering and radiological Sciences University of Michigan

Ge^＋ ions are implanted into fused silica glass at room temperature and a fluence of 1 × 10^17 cm^-2. The as-implanted samples are annealed in O2, N2 and Ar atmospheres separately. Ge^0, GeO and GeO2 coexist in the as-implanted and annealed samples. Annealing in different atmospheres at 600℃ leads each composite to change its content. After annealing at 1000℃, there remains some amount of Ge^0 in the substrates. However, the content of Ge decreases due to out-diffusion. After annealing in N2, Si N composite is formed. The absorption peak of GeO appears at 240 nm after annealing in O2 atmosphere, and a new absorption peak occurs at 418 nm after annealing in N2 atmosphere, which is attributed to the Si N composite. There is no absorption peak appearing after annealing in Ar atmosphere. Transmission electron microscopic images confirm the formation of Ge nanoparticles in the as-implanted sample and GeO2 nanoparticles in the annealed sample. In the present study, the GeO content and the GeO2 content depend on annealing temperature and atmosphere. Three photolumineseence emission band peaks at 290, 385 and 415 nm appear after ion implantation and they become strong with the increase of annealing temperature below 700℃ and their photoluminescences recover to the values of as-grown samples after annealing at 700℃. Optical absorption and photoluminescence depend on the annealing temperature and atmosphere.

关键词： nanoparticles optical absorption photoluminescence ion implantation

Energetics and structures of hydrogen-vacancy clusters in tungsten based on genetic algorithm

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Science China(physics,Mechanics & Astronomy) 2018年第10期61卷 100-103页

作者： LiFang Wang XiaoLin Shu GuangHong Lu Fei Gao department of physics Beihang University department of Nuclear Engineering and radiological Sciences University of Michigan

The behavior of hydrogen(H)in metals has been a longstanding research topic in materials science.One of the most compelling subjects is the deleterious effects of H on the microstructural evolution of materials;these effects include H embrittlement,superabundant vacancy formation,and blistering.Vacancies have been demonstrated through both experiments and computational simulations to have strong H trapping effects[1],resulting in increased H retention[2],

关键词：微结构基因算法聚类氢材料科学计算模拟表面修正钨

Role of monovalent co-dopants on the PL emission properties of YAl_3(BO_3)_4:Ce^(3+) phosphor

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Journal of Rare Earths 2014年第10期32卷 927-932页

作者： R.Satheesh Kumar V.Ponnusamy V.Sivakumar M.T.Jose department of physics Anna UniversityM.I.T. Campus Research and Development Laboratory Department of PhysicsSaveetha Engineering College radiological Sefety Division Indira Gandhi Centre for Atomic Research

The cerium （Ce3＋） doped yttrium aluminium borate （YAB） phosphor was synthesized by modified solid state reaction. The phosphor＇s phase purity and its emission properties were studied using powder X-ray diffraction pattern and photoluminescence spectroscopy. The synthesized YAB had rhomobohedral crystal structure. The phosphor had two different excitation and emission spectra. By 325 nm excitation, the phosphor had emission at 373 nm and with 363 nm excitation; the phosphor gave violet-blue emission at 418 nm. The UV emission of the phosphor originated due to Ce3＋ ions at the yttrium site and violet-blue emission owing to Ce3＋ ions at non-regular sites viz., A13＋ and interstitial sites. The emission intensity of the phosphor was enhanced when monovalent ions （K＋, Na＋, and F） were added as co-dopants. The crucial role of ionic radii of monovalent co-dopants on the emission enhancement of the YAB：Ce3＋ phosphor was reported. Thermogravimetric study showed that the YAB possessed high thermal stability at up to 900 ℃.

关键词： yttrium aluminium borate cerium monovalent codopants ionic radii thermogravimetric analysis rare earths

Effect of hydrogen on grain boundary migration in tungsten

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Science China(physics,Mechanics & Astronomy) 2015年第7期58卷 75-83页

作者： YU Yi SHU XiaoLin LIU YiNan NIU LiangLiang JIN Shuo GAO Fei LU GuangHong department of physics Beihang University department of Nuclear Engineering and radiological Science University of Michigan

Motivated by a grain boundary(GB) healing mechanism that GB turns into a mobile sink through migration to eliminate the vacancies in a bulk, we have further investigated the influence of the retained hydrogen(H) on the GB migration in tungsten using a molecular dynamics simulation. We show that H hinders the GB migration at different H concentrations and temperatures, and such friction of GB migration due to the presence of H increases with the H concentration and decreases with temperature. We demonstrate that H follows the GB-migration as the temperature is higher than 300 K. Most importantly, the presence of H induces a disordering of GB, which affects the GB migration significantly.

关键词：移动晶界钨氢分子动力学 GB 迁移接收器

Production of high-energy neutron beam from deuteron breakup

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Nuclear Science and Techniques 2022年第7期33卷 125-132页

作者： Ren-Sheng Wang Li Ou Zhi-Gang Xiao School of Radiation Medicine and Protection Medical College of Soochow UniversitySuzhou215123China Collaborative Innovation Center of radiological Medicine of Jiangsu Higher Education Institutions Suzhou215123China College of physics and Technology Guangxi Key Laboratory of Nuclear Physics and TechnologyGuangxi Normal UniversityGuilin541004China department of physics Tsinghua UniversityBeijing100084China

The deuteron breakup on heavy targets has been investigated in the framework of an improved quantum molecular dynamics model,focusing on the production of neutrons near zero degrees.The experimental differential cross sections of neutron production in the 102 MeV d+C reactions were reproduced by simulations.Based on the consistency between the model prediction and experiment,the feasibility of producing a neutron beam through the breakup of deuteron on a carbon target was demonstrated.Because of the nucleon Fermi motion inside the deuteron,the energy spectrum of the inclusive neutron near 0°in the laboratory exhibits considerable energy broadening in the main peak,whereas the long tail on the low-energy side is suppressed.By coincidentally measuring the accompanying deuteron breakup proton,the energy of the neutron can be tagged with an intrinsic uncertainty of approximately 5%(1σ).The tagging efficiency of the accompanying proton on the forward-emitted neutron can reach 90%,which ensures that the differential cross section in the(d,np)channel remains two orders higher than that in(p,n)after considering the measurement of accompanying protons.This enables the application of a well-defined energy neutron beam in an event-by-event scheme.

关键词： Deuteron breakup Monochromatic neutron High energy Quantum molecular dynamics