共查询到20条相似文献,搜索用时 15 毫秒
1.
Kousuke Morita Hiroshi Miyahara Yoshimune Ogata Keiji Katoh 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2005,540(2-3):324-327
105Rh becomes a stable 105Pd after β−-decay with a half-life of 35.36 h. The energies of especially strong γ-rays emitted from 105Rh are 306.1 and 318.9 keV, and the emission probabilities are evaluated to be 5.1±0.3% and 19.1±0.6% by de Frenne et al. To improve the certainty, the γ-ray emission probabilities were determined from the disintegration rate and absolute γ-ray intensities measured using a 4πβ(ppc)-γ(HPGe) coincidence apparatus with two-dimensional data-acquisition system. The results for the 306.1 and 318.9 keV γ-rays were 4.76±0.05% and 16.99±0.17%, respectively. 相似文献
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Nada Marnada Hiroshi Miyahara Naoyoshi Ueda Nobuo Hayashi Keiichi Ikeda 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2000,450(2-3):270-276
The emission probabilities of principal gamma-rays for 76As have been determined precisely with uncertainties less than 1% from measurement of disintegration rate and absolute gamma-ray intensities. The emission probabilities are smaller than those evaluated by Singh and Viggars (Nuclear Data Sheets 42 (1984) 233) by about 10% and hence the beta-ray branching ratio to the ground state has to be larger than about 10%. 相似文献
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Eduardo García-Torao M. Teresa Crespo Miguel Roteta Goedele Sibbens Stefaan Pomm Alejandro Martín Snchez M. Pilar Rubio Montero Simon Woods Andy Pearce 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2005,550(3):581-592
235U decays by α-particle emission to 231Th. The decay scheme of this nuclide is very complex, with more than 20 alpha branches. Recommended values for Pα of this nuclide are based on measurements carried out in 1975. This work presents the results of new measurements made with Si detectors and sources of enriched uranium in the frame of the EUROMET 591 cooperation project. The use of improved measurement techniques and numerical analysis of spectra allowed a new set of Pα values for 13 lines with improved uncertainties to be obtained. 相似文献
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用硅烷偶联剂对石墨烯表面进行修饰, 制备石墨烯/环氧树脂复合涂层。通过交流阻抗(EIS)和塔菲尔极化曲线(Tafel slope)等电化学方法分析复合涂层经伽马射线辐照后的腐蚀防护性能。采用电子自旋共振(ESR)和傅里叶红外光谱分析仪(FTIR)等测试复合涂层的γ射线辐照损伤, 探索了石墨烯在环氧树脂中抗辐照损伤的作用机理。Tafel结果显示复合涂层经280 kGy辐照后, 腐蚀电流为6.140×10-9 A/cm2, 而纯环氧树脂涂层的腐蚀电流则为1.340×10-8 A/cm2, 说明石墨烯可以使复合涂层保持较好的腐蚀防护性能。ESR分析表明, 复合涂层中的石墨烯可以降低环氧树脂基体在γ射线辐照过程中产生的过氧自由基, 表明石墨烯可有效吸收辐照过程中的自由基。辐照前后复合涂层的FT-IR图谱没有发生明显变化, 说明石墨烯有效降低了伽马射线对环氧树脂的结构损伤。因此, 可以认为石墨烯能够减缓环氧树脂在高能辐照环境中的老化, 从而延长其使用寿命。 相似文献
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W. Mczyski P. Bednarczyk J. Grbosz J. Heese M. Janicki K.H. Maier J.C. Merdinger K. Spohr M. Zibliski J. Stycze 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2007,580(3):1310-1326
A detector has been designed and built to assist in-beam γ-ray spectroscopy with fusion–evaporation reactions. It measures with high efficiency the evaporation residues that recoil out of a thin target into the angular interval from 1.8° to 9.0° at an adjustable distance of 1000–1350 mm from a target, in coincidence with γ-rays detected in a Ge-detector array. This permits filtering of such γ-rays out of a much stronger background of other reaction products and scattered beam. Evaporation residues are identified by their time-of-flight and the pulse height using a pulsed beam. The velocity vector of the γ-emitting recoil is also measured in the event-by-event mode, facilitating to correct the registered γ-ray energy for the Doppler shift, with the resulting significant improvement of the energy resolution. The heavy-ion detection scheme uses emission of secondary electrons caused by the recoiling ions when hitting a thin foil. These electrons are then electrostatically accelerated and focused onto a small scintillator that measures the summed electron energy, which is proportional to the number of electrons. The detector is able to operate at high frequency of the order of 1 MHz and detect very heavy nuclei with as low kinetic energy as 5 MeV. The paper describes the properties of the detector and gives examples of measurements with the OSIRIS, GAREL+ and EUROBALL IV γ-ray spectrometers. The usefulness of the technique for spectroscopic investigations of nuclei with a continuous beam is also discussed. 相似文献
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Yongjun Dong Guoqing Zhou Jun Xu Guangjun Zhao Fenglian Su Liangbi Su Hongjun Li JiLiang Si Xiaobo Qian Xiaoqing Li Jun Shen 《Optical Materials》2006,28(12):1377-1380
Gamma-ray irradiation induced color centers and charge state recharge of impurity and doped ion in 10 at.% Yb:YAP have been studied. The change in the additional absorption (AA) spectra is mainly related to the charge exchange of the impurity Fe2+, Fe3+ and Yb3+ ions. Two impurity color center bands at 255 and 313 nm were attributed to Fe3+ and Fe2+ ions, respectively. The broad AA band centered at 385 nm may be associated with the cation vacancies and F-type center. The transition Yb3+ → Yb2+ takes place in the process of γ-irradiation. Oxygen annealing and γ-ray irradiation lead to an opposite effect on the absorption properties of the Yb:YAP crystal. In the air annealing process, the transition Fe2+ → Fe3+ and Yb2+ → Yb3+ take place and the color centers responsible for the 385 nm band was destroyed. 相似文献
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Experimental evaluation of J–R curve in a crack growth situation requires ‘ηpl' and ‘γ' functions that are specific to a cracked geometry and loading condition. All derivations of existing ‘ηpl' and ‘γ' functions are for specific cracked geometry and loading. In this paper, direct limit load based general equations of ‘ηpl' and ‘γ' functions have been derived. Subsequently, new ‘ηpl' and ‘γ' functions, which are not available in the literature, for pipe and elbow geometry with various crack configurations under different loading conditions have been derived. The derivations of ‘ηpl' and ‘γ' functions for throughwall circumferentially cracked elbow under in-plane bending moment uses the very recently proposed new limit load formulas. 相似文献
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M.A. Saettel A. Sellam A. Nourreddine A. Pape 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2008,590(1-3):151
The RaMsEs Group (Radioprotection et Mesures Environnementales) of the IPHC performs research and offers services mainly in the field of radioactivity measurements and sample analysis. This report will describe some of our recent experience using a semiautomatic evaporation system to prepare large area thin deposits for total α and β counting and gives experimental and simulated results for the autoabsorption coefficients. 相似文献
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-Al2O3 prepared by combustion technique was ball-billed in a planetary mill in toluene medium at 300 rpm in ZrO2 pot with a ball to powder ratio 10:1 for 1, 5, 10, 15, and 20 hours. X-ray diffraction pattern from the milled materials showed super-Lorentzian peak shapes for -Al2O3 peak profiles. The super-Lorentzian peak shape has been attributed to the bimodal size distribution of the -Al2O3 particles. Rietveld analysis using two different phase fractions of -Al2O3 with different microstructural features yielded a low goodness-of-fit of the x-ray data indicating the suitability of the assumed model. The phase fraction of -Al2O3 particles with smaller size increases with the milling time. Further the particles shapes were observed to be cylindrical in this case with the cylinder axis along the crystallographic c-axis. The cylinder diameter and the length were obtained to be 86 and 140 respectively after 20 hrs of milling. The -Al2O3 particles of larger size are isotropic. It is, thus, proposed that milling induces bimodal size distribution in the initial hours of milling. 相似文献
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Effects of the addition of 1 weight percent (w/o) palladium on the thermal behavior of a lathe-cut type of high copper amalgam (13 w/o copper) were studied. Two identical alloys, with and without 1 w/o palladium were fabricated. X-ray diffraction studies of these amalgams have revealed the elimination of the γ2-phase by palladium addition. DSC thermograms of non-palladium-containing alloy indicated the existence of two γ1-phases, one with the transition temperature at 88 °C and the other at 109 °C. Aging for 18 months at 37 °C cannot eliminate the presence of the γ1-phase which has a low transition temperature. The addition of 1 w/o palladium into amalgam produced a more thermally stable amalgam. 相似文献
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Experimental evaluation of J–R curve in a crack growth situation requires ‘ηpl' and ‘γ' functions that are specific to a cracked geometry and loading condition. In Part I [Engng. Fract. Mech., in press] of this paper, new ηpl and γ functions, which are not available in the literature, for pipe and elbow geometry with various crack configurations under different loading conditions have been derived. In this paper, some of these newly proposed ηpl and γ functions have been validated experimentally through comparison of crack initiation load and J–R curve. In few cases, numerical validation has also been provided by comparing the J-integral values calculated through η factor approach and finite element method. 相似文献
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本研究发展了一种用于制备氧化物热电材料γ-NaxCoO2粉体的化学合成方法——聚丙烯酸钠(PAAS)凝胶法。主要研究了PAAS/Co2+摩尔比、原料浓度和煅烧温度对产物相组成及微观形态的影响规律, 探讨了物相形成机制, 同时用该方法结合SPS制备了不同Na离子浓度的NaxCoO2多晶样品, 并对其热电性能进行了表征。结果表明, PAAS/Co2+摩尔比对产物相组成产生了显著影响, 随着PAAS/Co2+摩尔比的增加, 样品的相组成由Co3O4相向单相γ-NaxCoO2转变, 合适的PAAS/Co2+摩尔比为0.8~1.1。而反应原料浓度对产物相组成的影响存在一个临界值(0.025 mol/L), 大于临界值抑制单相形成, 小于临界值促进单相形成。煅烧温度的升高有助于γ-NaxCoO2单相的形成, 800℃煅烧得到γ-NaxCoO2单相, 晶粒形态呈片状, 平均厚度约200 nm, 片状方向的尺寸在1~4 μm之间。随着Na含量的增加, 样品的Seebeck系数增大, 电导率增加, 热导率降低, 最终导致ZT值大幅增加。 相似文献
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Matthew D. Francis Olga V. Boltalina John F. Nixon Roger Taylor 《Fullerenes, Nanotubes and Carbon Nanostructures》2003,11(2):115-120
Evidence for the first η6 derivative of a fullerene, [MoC60F18(CO)3] has been obtained from reaction between [Mo(CH3CN)3(CO)3] and C60F18. 相似文献
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Facile Synthesis of γ‐In2Se3 Nanoflowers toward High Performance Self‐Powered Broadband γ‐In2Se3/Si Heterojunction Photodiode
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Shuo Chen Xuemei Liu Xvsheng Qiao Xia Wan Khurram Shehzad Xianghua Zhang Yang Xu Xianping Fan 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(18)
An effective colloidal process involving the hot‐injection method is developed to synthesize uniform nanoflowers consisting of 2D γ‐In2Se3 nanosheets. By exploiting the narrow direct bandgap and high absorption coefficient in the visible light range of In2Se3, a high‐quality γ‐In2Se3/Si heterojunction photodiode is fabricated. This photodiode shows a high photoresponse under light illumination, short response/recovery times, and long‐term durability. In addition, the γ‐In2Se3/Si heterojunction photodiode is self‐powered and displays a broadband spectral response ranging from UV to IR with a high responsivity and detectivity. These excellent performances make the γ‐In2Se3/Si heterojunction very interesting as highly efficient photodetectors. 相似文献
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Photoreflectance (PR) spectroscopy has been applied to the investigation of Si δ-doped GaAs, Al0.35Ga0.65As and AlAs layers grown by metal–organic vapor phase epitaxy (MOVPE) on GaAs substrates. The observation of Franz–Keldysh oscillations (FKO) and the application of fast Fourier transform (FFT) has allowed us to determine the internal electric field and, hence, the potential barrier between surface and δ-doped region of the layer. The FFT of the photoreflectance spectra has exhibited two separate heavy and light hole frequencies showing that the FKO in the PR signal are always the superposition of these two components. 相似文献
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Richard Akinyeye Mantoa Sekota Priscilla Baker Emmanuel Iwuoha 《Fullerenes, Nanotubes and Carbon Nanostructures》2006,14(1):49-55
A preliminary result of the morphology and yield of chemically synthesized polypyrrole (PPY) using β-naphthalene sulfonic acid (NSA) and ammonium peroxodisulphate (APS) in aqueous medium is presented. Various micro/nanotubes were obtained using different dopant/monomer (D/M) ratios and temperature settings. Similar but shorter and sheet-like nanostructures were obtained without the use of surfactant NSA; with a fibre-like, loose and admixed physical outlook. The percentage yield (m/v) of the doped PPY was greater than that from the undoped, being 27-44 and 18-20, respectively with higher values obtained from the low temperature synthesis. The highest percentage yield of 44 was obtained from a D/M ratio of 0.8. 相似文献