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提出一种利用手持式γ核素识别仪快速测量石材中天然放射性核素含量的方法。该方法借助低本底HPGe γ谱仪,运用能谱分析法确定手持式核素识别仪对226Ra、232Th、40K含量的刻度系数参考值;然后使用手持式γ核素识别仪测量石材中放射性核素γ能谱,利用经过刻度系数参考值修正后的测量结果,估算出石材中226Ra、232Th、40K的比活度。结果表明:该方法测量结果与低本底HPGe γ能谱仪分析结果的最大偏差为25.1%(CRa)、-27.2%(CTh)、-15.2%(CK),可适用于快速无损的检测石材样品γ放射性比活度,以及快速估算装饰石材所致的外照射剂量。 相似文献
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以实验室日常分析副样为原料,经过配料、研磨、均匀性检查和多家实验室间比对验证,获得了8个铀矿地质样品(ALBRIUG-1~ALBRIUG-8)中总α、总β、238U、232Th、226Ra、210Po和40K比活度值。采用最小称样量(50 mg)的ICP-MS检查均匀性时,2个铀矿地质样品(ALBRIUG-1和ALBRIUG-8)的均匀性较好,符合标准物质要求,可作为实验室天然放射性核素分析质量控制样品使用;其余6个样品( ALBRIUG-2~ALBRIUG-7)均匀性未达到标准物质要求,但样品放射性核素基本处于平衡状态,其铀镭平衡系数在0.988~1.079之间,可用于取样量较大(大于150g)的物理分析质量控制参考。 相似文献
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根据《建筑材料放射性核素限量(GB6566-2001)》标准:装修材料中天然放射性水平主要根据镭-226、钍-232和钾-40这三种核素的外照射指数和内照射指数来衡定,并规定采用低本底多道γ能谱仪进行测量。但是,γ能谱仪显示的是铀、钍、钾含量,不能直接给出放射性比活度数值,因此计算核素的内、外照射指数颇为不便。通过数学演算,得出根据放射性元素含量计算放射性比活度的计算公式,并且在实际工作中可以方便的运用。 相似文献
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本文介绍了电力行业在采用台区用户识别仪普查用户基础资料工作中,台区用户识别仪对现场安全防护措施的要求,测试环境对测试结果的影响,以及特殊情况下的测试方法介绍. 相似文献
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本文主要对环境X-γ剂量率仪的检定方法进行了探讨,根据所述方法使用地面放射性测量模型标准装置对环境X-γ剂量率仪进行了检定并对检定结果进行了验证。 相似文献
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针对轨道交通轮对几何尺寸检测需求不断增加、检测工具自动化水平低、检测精度低的现状,设计一种基于一维激光位移传感器的手持式轮对尺寸测量仪。该设备以STM32F407芯片作为微控制器,通过控制直线步进电机,配合激光位移传感器实现对轮对廓形二维点云数据的采集,采用基于中值误差与连续度调整权值的平滑算法对点云数据预处理,采用基于轮对轮廓特征的廓形匹配实现轮对尺寸参数的计算。该仪器对车轮轮廓进行全面记录和质量评估,试验证明,该设备在保持较高测量精度的情况下,同时具有高效测量、长时间工作等特点。 相似文献
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ABSTRACTNonlinearities in the application of fringe projection metrology make it very difficult to acquire perfect 3D data. This paper describes a six-step phase-shifting technique for a structured light measurement system with an off-the-shelf projector. First, the phase error is analysed and a gamma model is established by deriving the relative expression between the wrapped phase and input images. This is then expressed in matrix form to derive a unique solution, which is used for the gamma solver. The complex gamma calibration and projector error compensation can be removed once the gamma value of the off-the-shelf projector has been determined. The ideal model reconstruction results are obtained through simulations and experiments, and the standard deviation of the phase error is found to be only 0.0039 radians. Hence, the proposed method eliminates the nonlinear errors associated with fringe projection technology using existing projectors and improves the overall image reconstruction quality. 相似文献
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Wood-plastic-composites have been prepared using locally available soft wood and commercial monomers by vacuum impregnation
of monomer in wood and subsequent polymerization by gamma irradiation. The irradiation was performed by means of a60Co source of strength 50,000 Ci at 0·2 Mrad/h. The radiation dosage required for maximum conversion of monomer into polymer
was less than 2 Mrad except styrene which required a much larger dose of about 10 Mrad. The impregnation efficiency was found
to be more for wood with high pore volume. The impregnation efficiency also depended on the ambient pressure: the more the
vacuum, the more was the impregnation efficiency. Mechanical strength of the composites was found to be enhanced and water
absorption considerably reduced. X-ray diffraction studies showed that the crystallinity of the cellulose did not get affected
by the radiation polymerization which suggested that grafting of polymer on to the cell wall took place only in the amorphous
regions. 相似文献
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A digital coincidence method 总被引:1,自引:0,他引:1
V. I. Chernyshev S. V. Korostin Yu. N. Martynyuk A. S. Trofimov P. A. Iordanskii 《Measurement Techniques》2004,47(12):1204-1210
A digital coincidence method is described in which the amplitude is digitized and the time of each pulse from the ionizing radiation detectors is recorded. The features of the processing of the digital amplitude-time measurement data are described in detail. It is shown that the digital coincidence method has a time resolution defined solely by the resolving power of the detectors.Translated from Izmeritelnaya Tekhnika, No. 12, pp. 53–58, December, 2004.This revised version was published online in April 2005 with a corrected cover date. 相似文献
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该文介绍了行李放射性测控装置对^137Cs放射源活度响应的校;隹方法,利用点状放射源的活度与照射距离的平方成反比的核物理特性,测量行李放射性测控装置对某指定探测点的活度响应,根据一系列的活度响应值计算出行李放射性测控装置对^137Cs放射源活度响应的非线性。试验结果表明,活度响应是反映探测器对放射性辐射探测能力的重要参数,必须在规定的测量条件下进行测量。 相似文献
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弹性安装条件下机器结构声功率流的现场测量 总被引:3,自引:0,他引:3
本文利用互功率谱的方法对安装在混凝土地板上的小型排气扇工作时产生的结构声功率流进行了现场测量。对不同劲度系数的隔振支架对结构声功率流的影响进行了比较。 相似文献
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F. Torkzadeh F. Manouchehri F. Yoosefi Nejad A.H. Mohammadzadeh 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2007,580(3):1410-1413
Thermal neutron fluence between 1014 and 1018 n/cm2 in the Health Physics Research Reactor-Core of Tehran was measured conveniently by a TLD reader using the 6Li(n,)3H reaction in TLD-700. The primarily induced thermoluminescence (TL) by irradiation of the crystal in the reactor core was first cleared by annealing. The secondary TL of TLD-700 produced after a storage time by the absorbed energies of decayed tritons in crystal was used as a basis for assessment of prior exposure to neutrons. A thermal treatment stabilized the readings of the high-dose-irradiated dosimeters and reduced the influence of radiation damage in TLD-700. The response reduction as a consequence of high-dose radiation was corrected by Elemental Correction Coefficients (ECC) using gamma responses prior to in-core irradiation. The resulting correlation between neutron fluence and build-up TL of TLD-700 as a consequence of internal activity is presented. 相似文献
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为了实现高温环境下温度的准确测量,利用飞秒激光制备的光纤布拉格光栅(Fiber Bragg Gratings,FBG)杰出的热稳定性,提出一种基于飞秒光纤光栅的高温测量方法。利用光纤热光系数、热膨胀系数与温度之间的依赖关系,建立了FBG中心波长-温度模型;由于该模型不存在解析解,利用单点中心波长-温度特解和四次多项式拟合温度-中心波长工作曲线。基于该工作曲线和预退火(1 000℃,20 h)FBG在常温至900℃范围内进行温度测量实验,结果表明最大测量偏差不超过±2℃。本方法仅需标定单点中心波长-温度即可实现宽温度范围内的温度准确测量,简洁有效,在航空航天、核电冶金等领域中具有重要的研究和应用价值。 相似文献
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M.N. Nasrabadi F. BakhshiM. Jalali A. Mohammadi 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2011,659(1):378-382
Nuclear-based explosive detection methods can detect explosives by identifying their elemental components, especially nitrogen. Thermal neutron capture reactions have been used for detecting prompt gamma 10.8 MeV following radioactive neutron capture by 14N nuclei. We aimed to study the feasibility of using field-portable prompt gamma neutron activation analysis (PGNAA) along with improved nuclear equipment to detect and identify explosives, illicit substances or landmines. A 252Cf radio-isotopic source was embedded in a cylinder made of high-density polyethylene (HDPE) and the cylinder was then placed in another cylindrical container filled with water. Measurements were performed on high nitrogen content compounds such as melamine (C3H6N6). Melamine powder in a HDPE bottle was placed underneath the vessel containing water and the neutron source. Gamma rays were detected using two NaI(Tl) crystals. The results were simulated with MCNP4c code calculations. The theoretical calculations and experimental measurements were in good agreement indicating that this method can be used for detection of explosives and illicit drugs. 相似文献