Characterization of CdZnTeSe Nuclear Detector Chemically Etched in Bromine Methanol

Semiconductor nuclear radiation detectors made from tertiary and quaternary compounds of cadmium telluride (CdTe) can operate at room temperature without cryogenic cooling. One of such materials that have become of great interest is cadmium zinc telluride selenide (CdZnTeSe). Compared to other CdTe-based materials, such as cadmium zinc telluride (CdZnTe), CdZnTeSe can be grown with much less Te inclusions and sub-grain boundary networks. Chemical etching is often used to smoothen wafer surfaces during detector fabrication. This paper presents the characterization of CdZnTeSe that is chemically etched using bromine methanol solution. Infrared imaging shows that the wafer has no sub-grain boundary networks that often limit detector performance. The current-voltage (I-V) characterization experiment gave a resistivity of 4.6 × 1010 Ω-cm for the sample. The I-V curve was linear in the ±10 to ±50 volts range. An energy resolution of 7.2% was recorded at 100 V for the 59.6-keV gamma line of 241Am.

Analysis of Te and TeO₂on CdZnTe Nuclear Detectors Treated with Hydrogen Bromide and Ammonium-Based Solutions

Surface defects caused during cutting and polishing in the fabrication of cadmium zinc telluride (CdZnTe) nuclear detectors limit their spectral performance. Chemical treatments are often used to remove surface damages and defects. In this paper, we present the analysis of Te and TeO2 species on the surfaces of CdZnTe nuclear detectors treated with hydrogen bromide and ammonium-based solutions. The CdZnTe wafers were chemo-mechanically polished in a mixture of hydrogen bromide in hydrogen peroxide and ethylene glycol, followed by a chemical passivation in a mixture of ammonium fluoride and hydrogen peroxide solution. X-ray photoelectron spectroscopy showed significant conversion of Te to TeO2, thus producing a more chemically stable surface. The resistivity of the CdZnTe samples is in the order of 1010 ohms-cm. The current for a given applied voltage increased following the passivation and decreased after a 3-hour period. Results from spectral response measurements showed that the 59.5-keV gamma-peak of Am-241 was stable under the same channel for the surface treatment processes.

Study of Chemical Etching and Chemo-Mechanical Polishing on CdZnTe Nuclear Detectors

Cadmium zinc telluride (CdZnTe) semiconductor has applications in the detection of X-rays and gamma-rays at room temperature without having to use a cooling system. Chemical etching and chemo-mechanical polishing are processes used to smoothen CdZnTe wafer during detector device fabrication. These processes reduce surface damages left after polishing the wafers. In this paper, we compare the effects of etching and chemo-mechanical polishing on CdZnTe nuclear detectors, using a solution of hydrogen bromide in hydrogen peroxide and ethylene glycol mixture. X-ray photoelectron spectroscopy (XPS) was used to monitor TeO2 on the wafer surfaces. Current-voltage and detector-response measurements were made to study the electrical properties and energy resolution. XPS results showed that the chemical etching process resulted in the formation of more TeO2 on the detector surfaces compared to chemo-mechanical polishing. The electrical resistivity of the detector is of the order of 1010 Ω-cm. The chemo-mechanical polishing process increased the leakage current more that chemical etching. For freshly treated surfaces, the etching process is more detrimental to the energy resolution compared to chemo-mechanically polishing.

Collimated LaBr_3 detector response function in radioactivity analysis of nuclear waste drums

The properties of a Lanthanum bromide(LaBr3)detector and its response functions were investigated via experiments and simulations in this paper.The LaBr3detector had good relative energy resolution and higher efficiency than a high-purity germanium detector.Monte Carlo and other numerical methods were used to calculate the efficiencies of a LaBr3detector with a square collimation window.A model of the numerical method was established based on a pure geometric model that was consistent with the experimental situation.The results showed that the detector response functions calculated by these methods were in great agreement with experimental results.

Analysis of Nuclear Track Parameters of CN-85 Detector Irradiated to Thermal Neutrons by Using MATLAB Program

CN-85 detector which covered with boric acid H3Bo3 pellete has been irradiated by thermal neutrons from (241Am-9Be) source with activity 12 Ci and neutron flux 105 n. cm-2. s-1. The irradiation times-TD for detector were 4 h, 8 h, 16 h and 24 h. The track detector has been etched with sodium hydroxide. After chemical etching of the irradiated CN-85 detector, the images have been taken from a digital camera connected to the optical microscope. Image processing for the output images has been performed using MATALB program, and these images were analyzed and we had found the following relations: a) The relation between summation of opened track or surface density for tracks (intensity-IT) varies with radius of opening (track radius-RT). b) The relation between the tracks number-NT varies with the tracks diameter-DT (in micrometer) and tracks area-AT. That analysis of image processing was obtained, and the track intensity-IT was decreased with increase of track radius-RT at all of the irradiation time-TD. And the track intensity-IT was increased with increasing irradiation time-TD (h) for different track radius-RT (0.4225, 0.845, 1.2675 and 1.69 μm). The study indicates the possibility of using the analysis of image processing to CN-85 detector for classification of α-particle emitters through limitation of radius of track-RT, in addition to the contribution of these techniques in preparation of nano-filters and nono-membrane in nanotechnology fields.

Microstructural Investigation of PM-355 Nuclear Track Detector Subjected to Low-Dose Gamma Irradiation: A Positron Annihilation Lifetime Study

Samples of the PM-355 polymeric solid state nuclear track detector were exposed to low gamma absorbed doses from 1 kGy (0.1 Mrad) up to 9 kGy (0.9 Mrad). Positron annihilation lifetime (PAL) in conjunction with transmission electron microscopy (TEM) and Thermo-gravimetric analysis (TGA) were performed on irradiated and pristine samples at room temperature. The observed lifetime spectra were resolved into three components where the ortho-positronium (o-Ps) lifetime component was associated with the pick-off annihilation of positronium trapped by the free volume. PAL studies of irradiated PM-355 samples showed that ortho-positronium (o-Ps) lifetime increases with an increase in dose up to 4 kGy and decreases at higher doses. In contrast, the intensity of the o-Ps component, I3, decreases with the dose up to about 2 kGy, followed by a much smooth decrease up to 7 kGy, and then it levels off. TGA analysis indicated that the PM-355 detector decomposed in one main breakdown stage. These results are discussed on the basis of chemical and physical changes occurring at the microscopic level in the PM-355 due to irradiation. Crosslinking dominates for doses between 1 and 4 kGy, while the degradation mechanism (Chain scission) prevails for doses up to 9 kGy.

^238U and^232Th concentrations measured in different medical drugs by using solid-state nuclear track detectors and resulting radiation doses to the skin of patients

Urban populations in Morocco receive free medical drugs as prescribed by doctors in district health centres.To explore the exposure pathway of ^(238)U and^(232)Th and their decay products on the skin of patients,these radionuclides were measured in various medical drugs by using solid-state nuclear track detectors(SSNTDs).The measured concentrations range of ^(238)U and ^(232)Th in the medical drug samples of interest vary from(4.3±0.3) to(11.1±0.7) mBq 1^(-1) and(0.49±0.03) to(1.3±0.1)mBq 1^(-1),respectively.A new dosimetric model,based on the concept of specific alpha-dose and alpha-particle residual energy,was developed for evaluating radiation doses to skin following the application of different medical drugs by patients.The maximum total equivalent effective dose to skin due to the ^(238)U and ^(232)Th series from cutaneous application of different medical drugs by patients was found to be 2.8 mSv year^(-1) cm^(-2).

Measurement of Radon Gas Concentrations in Tap Water Samples for Thi-Qar Governorate Using Nuclear Track Detector (CR-39)

In the present work, we have measured the radon gas concentrations in tap water samples are taken directly from drinking tap water in sites houses being carried in Thi-Qar governorate by using nuclear track detector (CR-39). The results of measurements have shown that the highest average radon concentration in water samples is found in AL-Refai region which is equal to (0.223 ± 0.03 Bq/L), while the lowest average radon gas concentration is found in AL-Fajr region which is equal to (0.108 ± 0.01 Bq/L), with an average value of (0.175 ± 0.03 Bq/L). The highest value of annual effective dose (AED) in tap water samples is found in AL-Refai region, which is equal to (0.814 μSv/y), while the lowest value of (AED) is found in AL-Fajr region which is equal to (0.394 μSv/y), with an average value of (0.640 ± 0.1 μSv/y). The present results have shown that radon gas concentrations in tap water samples are less than the recommended international value (11.1 Bq/L). There for tap water in all the studied sites in Thi-Qar governorate is safe as for as radon concentration being concerned.

Nuclear Track Detectors for Relativistic Nuclear Fragmentation Studies: Comparison with Other Competitive Techniques

The potential of the high resolution nuclear track detector (NTD) CR-39 is examined carefully for the measurement of relativistic nuclear projectile fragmentation cross sections and studies of related processes using the experience of many years of such measurements. The charge resolution and the charge resolving power of CR-39 detectors for the measurements of 158 A GeV 207Pb projectiles and their fragments are presented. Exposures of target-detector stacks, the chemical etching procedure and the nuclear track measurements are described in detail discussing precautions and possible errors. The procedures discussed are also valid for other NTDs. A comparison with electronic active detectors is also made considering important detection and measurement aspects. An experimental design proposing the co-use of NTDs with in-use active detectors is described.

Failure Analysis on the Thrust Wear Detector of Turbine in Nuclear Power Plant

1GME037MV is the thrust wear detector of turbine.Before the turbine run up,the value of this channel often fluctuated.The engineer checked the channel,terminal,continuity,insulation,and driver and so on,no problem was found.At last,when disconnecting the end of the detector from the driver,then re-connected the end to the driver,the channel value is OK,after a while it became wrong again.Measured the resistance of the detector,it is 13O hm when the channel is OK,and 76 Ohm when the channel is wrong.According to the result of the checked,the conclusion is the character of the detector had changed.Both the measured value GME037MV and GME038MV are high 0.7mm,the turbine will trip,In the end the detector of GME037MV was replaced when the unit shut down.

基于脉冲X射线检测核辐射探测器的性能测试

目的:利用数字X射线摄影(DR)设备模拟脉冲X射线辐射场,测试常见的四种核辐射探测器性能,选择最适宜用于脉冲X射线检测的核辐射探测器。方法:控制DR设备的曝光时间由短到长,在20 ms~1000 ms之间选取10档,保持管电压81 kV不变,管电流在10 mA档位不变,测试不同曝光时间条件下核辐射探测器的性能。结果:闪烁体探测器最适用于短时高剂量脉冲X射线检测。结论:(1)G-M计数器、高气压电离室、NaI(Tl)探测器不适合用于曝光时间在1000 ms以下的短时高剂量脉冲X射线的检测。(2)塑料闪烁体探测器在曝光时间1000 ms以下有很好的时间响应,检测结果显示160 ms周围剂量当量率即达到稳定。

Study of CdZnTeSe Gamma-Ray Detector under Various Bias Voltages

Cadmium zinc telluride selenide (CdZnTeSe) is a new semiconductor material for gamma-ray detection and spectroscopy applications at room temperature. It has very high crystal quality compared to similar materials such as cadmium telluride and cadmium zinc telluride. The consistency of peak position in radiation detection devices is important to practical applications. In this paper, we have characterized a CdZnTeSe planar detector for bias voltages in the range of -20 V to -200 V and amplifier shaping time of 2, 3 and 6 μs. The peak position of the 59.6-keV gamma line of 241Am becomes more stable as the absolute value of the applied voltage increases. The best energy resolution of 8.5% was obtained for the 59.6-keV gamma peak at -160 V bias voltage and 3-μs shaping time. The energy resolution was relatively stable in the -120 V to -200 V range for a 6-μs shaping time. Future work will be focused on the study of the peak position and energy resolution over time.

金刚石核辐射探测器研究进展

金刚石核辐射探测器具有独特的物理性质,其载流子迁移率极高、暗电流极低、抗辐照和耐高温能力极强,可在复杂环境下进行辐射探测。本文综述了国内外金刚石材料制备,特别是通过化学气相沉积法制备高品质单晶金刚石方面的研究进展,总结了金刚石辐射探测器的研究及应用情况,并对金刚石核辐射探测器的前景进行了展望。

Silicon detector array for radioactive beam experiments at HIRFL-RIBLL

A new and innovative detector system based on a silicon strip detector dedicated to the study of the reaction induced by lighter radioactive beams is described herein.The detector system consists of five sets of three types of telescopes,which are successfully used to measure the angular distributions of both elastic scattering and breakup simultaneously, on the Radioactive Ion Beam Line in Lanzhou at Heavy Ion Research Facility in Lanzhou. This silicon detector array is used to measure the elastic scattering angular distributions of ^(11) Be on a ^(208) Pb target at E_(lab) = 140 and 209 MeV. A comparison of the Monte Carlo simulations with the experimental results shows a reasonable consistency.

New developments at nuclear emulsion experiment

Three new nuclear cmulsion techniques used for measuring emission angles ofcharged particles in central events at ultra-high evergy heavy-ion collisions are fully described.

2019—2020年我国部分非铀矿山氡浓度监测结果与分析

2019—2020年,选择我国黑龙江等11个省(自治区)的75座非铀矿山,采用固体核径迹探测器累积测量矿山氡浓度,结果显示,金属矿山55座(N=416),井下氡浓度算术均值(AM)为(1334±3301)Bq/m^(3),几何均值(GM)为(317±4.6)Bq/m^(3),范围22~28314 Bq/m^(3);非金属矿山16座(N=113)AM和GM分别为(162±151)Bq/m^(3)和(125±2)Bq/m^(3),范围22~971 Bq/m^(3)。井下529个测量点,氡浓度超过300 Bq/m^(3)的测量点占测量总数的31.8%,超过1000 Bq/m^(3)和2700 Bq/m^(3)的测点分别占测量总数的19.8%和9.3%。21座金属矿山井下氡浓度超过1000 Bq/m^(3),占调查总矿山的28%。金属矿山矿工的年有效剂量均值为8.38 mSv,非金属矿山矿工的年有效剂量均值为1.01 mSv。可以看出,我国金属矿山井下氡浓度高的问题很突出。建议今后加强金属矿山工作场所氡的监测和矿工氡个人剂量监测,加强通风工程防护,并借鉴国际机构的管理模式,尽快实行分级管理。

Determination the Effect of Gamma Radiation and Thermal Neutron on PM-355 Detector by Using FTIR Spectroscopy

The effect of gamma on nuclear track detector type PM-355 (at the dose range 200 to 1600 kGy) and thermal neutron (flux 105 n·cm-2·s-1) was calculated by using of two irradiation methods. First method (G + N) was an irradiation PM-355 detector by gamma radiation and then irradiation by thermal neutrons, and another method (N + G) was irradiated by thermal neutrons and then gamma radiation. FTIR-spectroscopy was used to measure the change in deferent of transmission percent ΔT% at the wavenumber 1260 cm-1 with wavenumber 2962 cm-1 [ΔT%]1260-2962 and wavenumber 1138 cm-1 [ΔT%]1260-1138. The values of [ΔT%]1260-2962 and [ΔT%]1260-1138 were increasing with the increase of gamma irradiation with maximum response at 820 kGy and then drop after this dose until to 1600 kGy. This study determined the linear equations relation between the effect of gamma radiation on PM-355 detector and the change of [ΔT%]1260-2962 and [ΔT%]1260-1138, and this change appeared in (N + G) irradiation method better than in (G + N) irradiation method. The appearance of wavenumber 2964 cm-1 in (G + N) irradiation method referred to alkyl asymmetry C-H bond stretched out of skelated plane after changes in chemical structure of PM-355 detector by gamma or neutrons radiation.

A New Method to Determine the Maximum Value of the Track Length of Alpha Particle in CR-39 Detector

The aim of this paper is to determine the maximum values of the track length (Lmax) of alpha particles in Nuclear Track Detector (type CR-39) using a new method by taking the relation between the etching time and the diameter square of alpha particle with different energies at constant bulk etch rate VB (1.45 μm/hr) by using TRACK_TEST program from Brun et al. function and Yu et al. function. Using the new equation, the maximum values of the track lengths of alpha particles measured in CR-39 detector have been found to be in a good agreement with the values measured by using Brun et al. function and Yu et al. function in TRACK_TEST program.

碲锌镉器件技术进展及其在SPECT中的应用

核医学成像设备中的探测器是整个设备的核心部件。基于闪烁体探测器的核医学成像设备存在光电转换效率低和能量分辨率差等关键问题,短期内难以有效解决。而近年来碲锌镉半导体探测器的发展使得核医学成像设备在能量分辨率和空间分辨率等方面取得了很大的提高。本文以单光子发射计算机断层成像(SPECT)技术为例,首先介绍了核医学成像原理及设备组成,然后从碲锌镉探测器的工作原理及基本结构出发,综述了碲锌镉探测器的新技术及其在临床核医学的应用,最后结合核医学领域应用的需求展望了碲锌镉探测器的研究重点和技术发展趋势。

辉县市乡村第三产业空间分布规律及影响因素

【目的】探究县域乡村第三产业空间分布特征及其与各影响因素间的空间关系。【方法】采用核密度分析、双变量空间自相关分析、地理探测器等方法,从多尺度视角下对辉县市第三产业兴趣点(point of interest)的空间分布特征及影响因素进行研究。【结果】1)辉县市第三产业高密度区乡村主要位于主城区城关街道及周边乡镇,核密度低值区位于研究区的西南及北部。2)第三产业整体与人口密度表现出空间正相关关系,与坡度、地形起伏度、道路距离、河流距离表现出空间负相关关系。3)第三产业与地形因素的空间识别表现为东南低-低聚集与西北低-高聚集;与道路距离、河流距离主要表现为低-高聚集与低-低聚集;与人口密度表现为低-低聚集与高-高聚集,其中流通部门类聚集面积和扩散规模表现明显低于其他类型,生活生产类与地形因素的高-高聚集区出现较为明显的聚集现象。4)在0.5 km×0.5 km尺度上,现有产业的分布受人口密度和河流距离的影响,而在1.0 km×1.0 km、1.5 km×1.5 km尺度上人口密度和道路距离对产业分布的驱动力最强。【结论】保持辉县市南部平原地区第三产业平稳发展,加强北部以薄壁镇、上八里镇、黄水乡、沙窑乡等区域的第三产业发展,利用辉县市独特的自然优势,采取产业转型整合的发展策略,促进生态环境与第三产业的融合发展;同时加强交通路网的建设,加强产业协作、旅游协同、交通连接。