共查询到16条相似文献,搜索用时 0 毫秒
1.
2.
3.
A thorough knowledge of the primary spectrum is very important to perform a quality control (QC) of X-ray tubes. In previous works, a methodology to assess primary spectrum using a Compton spectrometer and applying the Monte Carlo (MC) method has been analyzed. By means of a Monte Carlo model, a response matrix can be built, relating the Pulse Height Distribution (PHD) recorded in the detector to the primary X-ray spectrum. Subsequently, an unfolding method based on the application of a Modified Truncated Singular Value Decomposition (MTSVD) is applied to the response matrix to assess the primary spectrum. Germanium (Ge), Silicon (Si) and Cadmium-Telluride (CdTe) detectors are considered in this work. The main goal of the paper is to determine whether the MTSVD unfolding method is adequate to provide an acceptable reproduction of spectra for these detectors. 相似文献
4.
5.
《Fusion Engineering and Design》2014,89(7-8):1417-1420
The absorption of rare gas in the lead-lithium has been quite low and the gas is used as a cover-gas to control the environment of experiment. In our previous thermo-fluid experiment by using lithium-lead, it was found the cover gas pressure enclosed in the very leak tight container of lithium-lead was decreased with time, that is, the gas-absorption of the solid lithium-lead occurred at room temperature under atmospheric pressure. The variation of pressure exceeded the retention of argon in lead-lithium which is expected by the published data. Therefore, we aim to confirm those phenomena under well-controlled experimental condition by using argon, nitrogen and helium. According to the results of gas exposure tests, the absorption of argon in the lead-lithium is comparable with that of helium even at the solid state. For the molten state of lead-lithium, the absorption of argon could be larger than that of helium. It is also observed from the TPD-MS analysis that the argon tends to desorb when the phase change of lead-lithium occurs. If the retention of argon in the lead-lithium cannot be ignored, the problem of Ar-41 activity should be taken into consideration as well as the problem of argon bubble in the lead-lithium. 相似文献
6.
半导体器件与电路辐照响应测试系统 总被引:3,自引:3,他引:0
介绍用于测量MOS电容、MOSFET、半导体元器件和集成电路辐照效应的微机测试系统及其功能,并给出该系统在半导体辐射损伤研究甲的应用实例. 相似文献
7.
Fang Cheng Qiren Zhang Hailin Qiao Xiuwen Zhou 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(15):2403-2407
The experiments indicate that the perfect KMgF3 crystal has no absorption in the visible range, however the electron irradiation induces a complex absorption spectrum. The absorption spectra can be decomposed by five Gaussian bands peaking at 2.5 eV (488 nm), 3.4 eV (359 nm), 4.2 eV (295 nm), 4.6 eV (270 nm) and 5.2 eV (239 nm), respectively. The purpose of this paper is to seek the origins of the absorption bands. The electronic structures and absorption spectra either for the perfect KMgF3 or for KMgF3: with electrical neutrality have been studied by using density functional theory code CASTEP with the lattice structure optimized. The calculation results predicate that KMgF3: also exhibits five absorption bands caused by the existence of the fluorine ion vacancy and the five absorption bands well coincide with the experimental results. It is believable that the five absorption bands are related to in KMgF3 crystal produced by the electron irradiation. 相似文献
8.
CorrelationbetweeninducedembryotoxicityandabsorptiondoseofenricheduraniumintestesZhuShou-Peng(朱寿彭)andLunMing-Yue(伦明跃)(SuzhouM... 相似文献
9.
研究了机体内污染^134Cs在小鼠骨骼中的滞留过程和吸收剂量诱发骨髓嗜多染红细胞生核率的量效关系及其持续作用特性。由^134Cs在骨骼中滞留动态拟合方程导出其半滞留其为5.73天;^134Cs诱发骨髓PCE的微核形成率随机体摄入^134Cs放射性活度的增加而升高,且在骨髓PCE微核形成率与摄和^134Cs放射性活度之间 相似文献
10.
In this article, principle and mathematical method of determining the phase fractions of multiphase flows by using a dual-energy γ-ray system have been described. The dual-energy γ-ray device is composed of radioactive isotopes of 241Am and 137Cs with γ-ray energies of 59.5 and 662 keV, respectively. A rational method to calibrate the absorption coefficient was introduced in detail. The modified arithmetic is beneficial to removing the extra Compton scattering from the measured value. The result shows that the dual-energy γ-ray technique can be used in three-phase flow with average accuracy greater than 95%, which enables us to determine phase fractions almost independent of the flow regime. Improvement has been achieved on measurement accuracy of phase fractions. 相似文献
11.
The molar extinction coefficients at the absorption maximum of the solvated electron spectrum have been evaluated to be 900,970,and 1000 mol~(-1).m~2 for 1,2-ethanediol (12ED),1,2-propanediol (12PD),and 1,3-propanediol (13PD),respectively.These values are two-third or three-fourth of the value usually reported in the published report. Picosecond pulse radiolysis studies have aided in depicting the radiolytic yield of the solvated electron in these sol- vents as a function of time from picosecond to microsecond.The radiolytic yield in these viscous solvents is found to be strongly different from that of the water solution.The temperature dependent absorption spectra of the solvated electron in 12ED,12PD,and 13PD have been also investigated.In all the three solvents,the optical spectra shift to the red with increasing temperature.While the shape of the spectra does not change in 13PD,a widening on the blue side of the absorption band is observed in 12ED and 12PD at elevated temperatures. 相似文献
12.
Isospin-dependent Quantum Molecular Dynamics model (IQMD) has been applied to investigate the Pygmy Dipole Resonance (PDR) and Giant Dipole Resonance (GDR) in Ni isotopes by Coulomb excitation. By Gaussian fitting to the photon emission spectra, the peak energies and strengths of PDR and GDR are extracted. Their sensitivities to impact parameter, incident energy and the symmetry energy are discussed. By the comparison of energy-weighted sum rule (EWSR) with the data and other calculations for 68 Ni, the parameters of density-dependence of symmetry energy in the IQMD are constrained. In addition, the N/Z dependence of PDR and GDR parameters of Ni isotopes are investigated, and the results that the EWSR increases linearly with the N/Z are obtained. 相似文献
13.
A plasma-based stable,ultra-wideband electromagnetic (EM) wave absorber structure is studied in this paper for stealth applications.The stability is maintained by a multi-layer structure with several plasma layers and dielectric layers distributed alternately.The plasma in each plasma layer is designed to be uniform,whereas it has a discrete nonuniform distribution from the overall view of the structure.The nonuniform distribution of the plasma is the key to obtaining ultra-wideband wave absorption.A discrete Epstein distribution model is put forward to constrain the nonuniform electron density of the plasma layers,by which the wave absorption range is extended to the ultra-wideband.Then,the scattering matrix method (SMM) is employed to analyze the electromagnetic reflection and absorption of the absorber structure.In the simulation,the validation of the proposed structure and model in ultra-wideband EM wave absorption is first illustrated by comparing the nonuniform plasma model with the uniform case.Then,the influence of various parameters on the EM wave reflection of the plasma are simulated and analyzed in detail,verifying the EM wave absorption performance of the absorber.The proposed structure and model are expected to be superior in some realistic applications,such as supersonic aircraft. 相似文献
14.
15.
U. SpechtM. Busch J. SeifertH. Winter K. GärtnerR. W?odarczyk M. SierkaJ. Sauer 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2011,269(9):799-803
Fast He atoms with energies from 200 eV up to 16 keV are scattered under grazing polar angles of incidence from a flat and clean KCl(0 0 1) surface. For scattering along low-index directions (axial surface channeling) we observe pronounced peaks in the angular distributions of scattered projectiles which can be attributed to rainbow scattering. From classical and semiclassical trajectory calculations based on individual Hartree-Fock pair and density functional theory (DFT) potentials, we obtain corresponding rainbow angles for comparison with the experimental data. The calculations were performed taking into account the rumpling of K and Cl in the topmost surface layer. Fair agreement with the experimental data is found for scattering along 〈1 0 0〉 for DFT as well as individual pair potentials calculated from Hartree-Fock wave functions. 相似文献
16.
P. LuH. Zhang T. SatohT. Ohkubo A. YamazakiK. Takano T. KamiyaL. Zhu Y. HuangZ. Jiang Yi ZhengM. Yang Y. MiQ. Ren H. Shen 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2011,269(17):1940-1943
The structural stability of water-soluble ZnO quantum dots (QDs) in oral epidermoid carcinoma (KB) cells was studied by the External Micro Proton Induced X-ray Emission (External Micro-PIXE) technique and the X-ray absorption fine structure (XAFS) measurement. The External Micro-PIXE and XAFS experiments were respectively performed at the JAEA and the Shanghai Synchrotron Radiation Facility. The elements’ distributions were detected by the External Micro-PIXE technique. The XAFS method was applied to obtain information about zinc (Zn) K-edge spectra. The fits of the XAFS data showed that the Zn-O bond structure of water-soluble ZnO QDs was stable after being absorbed by KB cells. Its local structural parameters were almost identical with those of the standard wurtzite structure. Water-soluble ZnO QDs had good structural stability in KB cells. 相似文献