用γ谱仪测定高温焚烧炉炉渣中的放射性核素

一、引言 高温焚烧炉是一种处理中低放固体废物的装置,它可将废物中的绝大部分放射性核素安全地包容于颗粒状的炉渣之中。这种炉渣的主要成份是氧化硅和氧化铁。对炉渣中放射性核素的测定可用常规的放化方法来实现,即破碎、溶解、分离及最后的放射性测量。显然,这是十分烦杂的,而非破坏性的直接测量无疑要简单得多。射线通过物质时由于吸收作用而衰减。虽然γ射线有较强的穿透能力,它毕竟要在某种程度上为物质所吸收。非破坏测量的     

用NaI谱仪识别γ放射源

采用NaI谱仪系统,开展了放射源辐射指纹识别技术研究。利用数据库开发平台,采用谱形比较法、半衰期修正法和谱形相似度等概念,编制了放射源辐射指纹识别软件,实现了放射源在线可视化识别,并通过放射源同一性的识别实验验证了软件的有效性。研究结果表明:在总计数和峰面积识别条件下,能较快实现放射源同一性的识别。     

圆柱体模型放射性核素比活度的HPGeγ谱仪就地测定

本工作采用一台便携式HPGeγ谱仪系统,对核工业航测遥感中心二级放射性计量站的地面圆柱体放射性模型（φ220cm×60cm,以下简称圆柱体模型）的放射性核素比活度进行了就地测量分析。 谱仪系统采用美国ORTEC公司生产的GHX-20190-P-LP型 HPGeγ探测器,其晶体几何尺寸为φ54.8mm×57.9mm,相对探测效率ε=30.3％,对60Co　1.332 5 MeV的能量分辨率FWHM     

高纯锗γ谱仪测量准确度影响因素分析

使用高纯锗γ谱仪检测放射性核素时,测量结果准确度受多个因素影响,对谱仪选用、谱仪刻度、样品制备、样品测量、结果校正等各个方面进行分析,提出了一系列针对性建议,研究表明合理地进行检测可提高检测结果的准确度.     

就地γ谱仪蒙特卡罗计算软件研制

在某种环境中,放射性核素按一定规律分布在土壤表面及土壤中。核素衰变时,各向同性地发射出特定能量的γ射线。通过对γ射线的探测,可得到土壤中该核素的放射性活度。 为了配合对土壤环境中特定核素放射性活度的就地γ测量,针对特定的谱仪研制了专用的蒙特卡罗模拟程序,用于模拟核素衰变发出的γ射线经过土壤层、空气层及其它屏蔽物进入探测器晶体,并与晶体作用,以一定几率（探测效率ε）被探测器记录下来的过程。利用该程序,可以得到γ谱仪测量计数率与土壤中核素的比活度关系以及相应的剂量率,并给出核     

低本底反康普顿HPGe γ谱仪的调试

本文报道的低本底反康普顿ＨＰＧｅγ谱仪．ＨＰＧｅ探测器对￣（６０）Ｃｏ的１３３２ｋｅｖγ射线的相对探测效率为３８．３％．能量分辨率为１．７７ｋｅＶ。在阱型反符合屏蔽下．对放在探测器端面的￣（１３７）Ｃｓ点状薄膜源的峰康比可达６８５．８：１；测量时间１００ｍｉｎ．置信度９５％时．￣（１３７）Ｃｓ点源的最小判断限为１．１２ｘ１Ｏ￣（－４）Ｂｑ。在物质屏蔽和阶型反符合屏蔽下，在５０～２１５２．８ｋｅＶ能区的积分本底为０．３４３ｓ￣（－１）。与无反符合屏蔽时相比，压缩系数大于４．５．对￣（１５２）Ｅｕ体源，谱仪积分非线性为０．０２７％。     

环境测量用NaI(Tl)γ谱仪

本文报道以φ100×100mm的低钾NaI(T1)晶体和GDB-76F型光电倍增管组合探头为探测器的室内外通用γ谱仪。在铅屏蔽室内,γ光子能量从0.05—2MeV范围本底计数率为1053计数/min。对~(137)Cs面源(φ5mm)的γ射线能量分辨率<10％,全能峰效率为16.3％,测量1000min,置信水平为95％,最小可探测下限为0.06Bq。环境就地测量20min可分析出10m半径范围内土壤中U系,Th系、~(40)K和~(137)Cs等核素的比放活度,并可给出距地面1m高处它们各自的γ吸收剂量率及总吸收剂量率值。     

穆斯堡尔谱仪用的反散射式探测器

本文叙述了穆斯垒尔谱仪采用反散射式探测器的工作原理、特点、结构和它的性能。通过实测得到了不同     

HPGe低本底反康普顿γ谱仪

鉴于短链异羟肟酸作为良好的络合剂应用于Purex流程的可能性，本工作用pH滴定法研究了AHA、FHA和N-FHA与UO2^2 的配合稳定性。室温(约24℃)下，首先测得几种异羟肟酸的离解常数(pKa)分别为：AHA，9．47(9．49)；FHA，8．74(8．90)；N-FHA，7．92。然后根据它们的离解常数求出不同离了强度下与UO2^2 形成的配合物逐级稳定常数lgβ1、lgβ2(表1)。     

手持式伽玛能谱仪数据存储方法研究

为了解决手持式伽玛能谱仪512条谱线数据的存储与管理,采用超低功耗微处理器MSP430F5438和M25P16接口构成能谱数据存储电路,并合理地分配了M25P16和MSP430F5438 Flash的存储功能。根据磁盘数据存储与管理方法,研究了能谱曲线数据的特征,定义和建立了谱线数据索引字段区。分析了M25P16的写和读时序,研究出能谱曲线数据存储和管理方法。通过编程、调试和实验,验证了上述研究的能谱磁盘数据存储管理方法可行,能谱数据写、读和擦除时间能够满足能谱仪操作需要;该方法大大减少了Flash的写入次数,延长了其使用寿命;该方法所使用的存储电路结构简单,功耗低。     

Use of Natural Radioactive Elements for Detection Efficiency Calibration of Gamma Spectrometers

It is concluded on the basis of measurements performed on preparations of potassium, lanthanum, and uranium using a gamma spectrometer with a detector made of ultrapure germanium that such preparations can be used for calibration with respect to the detection efficiency using the appropriate constants (the half-life, quantum yield, and radionuclide content in the environment). Corrections taking account of the difference in the absorption of rays in the materials in the preparations used for the measurements and the calibration source are calculated. For the constants used in the present work to characterize the radiation of ²³⁴Th (63.3 and 92.6 keV), the measured activity is significantly lower (by 26%) than the value calculated from the mass of the uranium introduced into the experimental preparation (²³⁸U is in radioactive equilibrium with ²³⁴Th).     

Neutron and Gamma Sensitivities of Dynamic Detectors

The neutron and gamma sensitivities of nine detectors were studied in experiments performed at the Sandia Pulsed Reactor (SPR). Of the detectors tested, six are predominantly gamma detectors at the SPR and three produce a significant fraction of their total current due to the neutron flux during a normal SPR burst. None of the detectors studied were found to be predominantly sensitive to the neutron flux during a normal SPR burst. Tests performed at pure gamma sources on a P-Intrinsic-N (PIN) diode detector are also described. The neutron induced current in the silicon detectors is treated theoretically.     

New Developments in Gas-Filled Image Intensifier Detectors for X and Gamma Rays

In spark operation, with short-circuit electronics having a triggering delay of ? 40 ns and yielding a peak current of 15 amperes, the detector, which is filled with xenon (720Torr) and diethylamine (40 Torr) has a counting plateau equal to 4% of the mean operating voltage. The electronic short-circuit is more effective when diethylamine replaces methylal. It is shown that this vapour produces a delay in the triggering of the spark. The life is improved. Study of electron avalanches has shown that, in the case of detection of X-rays of a mean energy of 27 keV, the number of carriers which they contain may reach 108 and that the probability is then less than 10-4 for triggering sparks. These avalanches also make it possible to obtain completely proportional amplitude spectra of excellent resolution (9% for 27 keV). When the detector is used in avalanche operation, the light emitted by the latter enables an image of the X-ray emitting source to be recorded. The quantity of light emitted can be increased by increasing the number of carriers in the avalanche but at the risk of creating a spark. This risk is eliminated by a short-circuit system similar to that operating for spark conditions but with a triggering threshold corresponding to about 105 electrons. The possibility of using this detector for recording X-ray diffraction patterns on biological molecules is discussed.     

Monte Carlo Simulation of Determining Porosity by Using Dual Gamma Detectors

Current formation elementsspectroscopy logging technology utilize ²⁴¹Am-Be neutron source andsingle BGO detector to determine elements contents. It plays an important rolein mineral analysis and lithology identification of unconventional oil and gasexploration, but information measured is relatively limited. Measured systembased on ²⁴¹Am-Be neutron and dual detectors can be developed torealize the measurement of elements content as well as determine neutron gammaporosity by using ratio of gamma count between near and far detectors.Calculation model is built by Monte Carlo method to study neutron gamma porositylogging response with different spacing and shields. And it is concluded thatmeasuring neutron gamma have high counts and good statistical propertycontrasted with measuring thermal neutron, but the sensitivity of porositydecrease. Sensitivity of porosity will increase as the spacing of dual detectorincreases. Spacing of far and near detectors should be around 62 cm and 35 cmrespectively. Gamma counts decrease and neutron gamma porosity sensitivityincrease when shield is fixed between neutron and detector. The length of mainshield should be greater than 10 cm and associated shielding is about 5 cm. ByMonte Carlo Simulation study, the result provides technical support fordetermining porosity in formation elements spectroscopy logging using ²⁴¹Am-Beneutron and gamma detectors.     

Numerical Determination of Potential Distribution inside Single Open Ended HPGe Gamma Detectors

The first numerical evaluations are presented of potential distribution inside single open ended HPGe ? detectors. The depletion voltage and the internal potential distribution are determined as functions of geometrical parameters and impurity concentration (also allowed to be non-uniform inside the detector).     

γ辐射对堆芯自给能探测器探测性能影响研究

为确定堆芯γ射线对自给能探测器输出信号的影响。将钒和铑自给能探测器放置在试验堆某一稳定的中子和γ辐照水平下,通过停堆给自给能探测器施加一个中子注量率阶跃信号,观察探测器输出信号的变化来推断γ射线对自给能探测器输出信号的影响。     

Millimeter-Scale PIG Source for Miniature Mass Spectrometers

A new millimeter-scale penning ion generator (PIG) ion source has been developed for miniature mass spectrometers. The cathode is a 40?mm diameter?×?2?mm long stainless steel cylinder with a hole of 4?mm, the anode with a hole of 12.6?mm and a length of 6.4?mm is made in stainless steel, and the ion emission hole size on the anticathode is 5?mm. Several microamperes of H⁺ ions can be extracted with less than 10?W discharge power consumption. The PIG ion source is shown to have advantages of long lifetime under high-pressure operation and low power consumption. The ion source is being designed and investigated for use in miniature mass spectrometer; however this ion source is thoroughly described so that it can be easily implemented by other researchers for other applications.