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.

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.

Research and applications of nuclear tracks: Developments in Pakistan and global comparison

The present paper describes the development and applications of nuclear track detection technique in Pakistan. Pakistan entered in the field of nuclear tracks in early 1970s when it was still quite new. Highlights of successes of different Pakistani laboratories, working on nuclear tracks, achieved on their own or in collaboration with similar centers in the world are described briefly. The robust features of this investigation are the comprehensive investigation of the addressed research, analysis and review of results, and discussions with the perspectives of applications and new research directions. Further analysis of the published results by the present author and some new results are also presented. This paper portrays a comprehensive picture of the nuclear track detection research and technology in Pakistan and can be useful for a similar development in any country around the globe.

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).

A compound spike model for formation of nuclear tracks in solids

Formation of nuclear tracks in solids has been described as a thermal spike as well as a Coulomb explo- sion spike.Here,formation of nuclear tracks is described as a compound spike including partial roles of both thermal and Coulomb explosion spikes in track formation.Fractional roles of both spikes depend on atomic and electronic structure of a track detector and deposited energy density in the track detector by the incident charged particle.Be- havior of the cylindrical zone along the path of the incident particle is described mathematically in terms of bulk and individual atomic flow or movement.Defect structure of the latent nuclear tracks is described and conditions of con- tinuity and discontinuity of latent tracks are evaluated and discussed.This paper includes mathematical description, analysis and evaluation of the nuclear track formation issue in the light of published experimental and theoretical re- sults,which are useful for users of nuclear track detection technique and researchers involved in ion beam induced materials modification and ions implantation in semiconductors.

Mapping of Radon (²²⁰Rn and ²²²Rn) Concentration Distribution in a Microclimate Condition Cellar Using Nuclear Track Methodology

This work presents the results of the Radon (220Rn and 222Rn) measurements made with 486 chips of CR-39 (Allyl Dyglicol Poly Carbonate) MASL? bared detectors, in a reticular mode distribution, inside of a cellar with average indoor radon concentration 862 ± 49 Bq/m3. The exposure time was 3 months, in microclimate condition of constant temperature, humidity, barometric pressure and no airflow. After these 3 months, all the detectors were chemically etched in KOH 6.25 M solution at 60°C ± 1°C for 18 hours, following a very well established protocol for indoor radon survey by the Dosimetry Applications Laboratory of the Physics Institute of the National Autonomous University of Mexico, and later read automatically by CADIS (Counting Automatically Digital Image System). The results show that each one of the nine measured planes is not homogeneous presenting important differences of indoor radon concentration values. Specifically, the Radon (220Rn and 222Rn) concentration levels vary for each measured point within the cellar. It is a very important observation to consider for the calculation of dose and radiological risk.

Microscopic Observation of Nuclear Track Pores in Polymeric Membranes

Nuclear track pores were develop and observed in polycarbonate and LR-115 membranes. The polymer membranes were irradiated by swift heavy ions (SHI) and etched chemically. The stopping range of heavy ion is larger than the thickness of the membrane. The fluence of ions was changes from 103 to 107 ions-cm-2. The etching time was increased till pore size reaches up to micron range. The etching conditions were set to develop the porous tracks. The tracks are revealed under optical microscope as the size reaches up to micron or sub-micron size. The size was measured using standard electron diffraction grid. Results show that the porous tracks having average size of 2.4 micron can be developed in polycarbonate, while 5 - 10 micron porous tracks can be developed in LR-115.

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.

Feasibility of probing solid state nuclear tracks by thermal analysis method

The feasibility of probing solid state nuclear tracks by thermal analysis method is discussed both theoretically and experimentally.Comparison is made between the thermal analysis method and the optical microscope method,and it is demonstrated that this thermal analysis method is applicable to probing solid state nuclear tracks.

Measurement of solid state nuclear tracks in apatite by thermal analysis method

A new measurement method of thermal analysis for solid state nuclear tracks is proposed.The annealing heat emitted by the unit mass of solid state nuclear tracks in heavy particles of the sample is determined via micro-thermal analysis method.Hence,the number of solid state nuclear tracks in the unit mass of sample is determined.In particular,this paper introduces the method and its significance to measure the number of α-particles nuclear tracks in apatite by measuring the annealing heat of α-particles nuclear tracks.In addition,the mechanism of the measurement and potential applications are discussed.

基于升降轨SAR数据的地下核爆参数反演与3D形变监测方法

以朝鲜第6次地下核试验为例,基于升降轨ALOS-2 SAR数据,首先利用D-InSAR技术获取核试验场的视线向形变,以此为基础,基于贝叶斯反演方法确定核爆参数,然后引入POT技术测量核试验场方位向和距离向形变,最后,融合D-InSAR与POT结果计算核试验地表三维形变场.研究发现,核爆位于朝鲜丰溪里试验场万塔山下,其坐标为东经129.0792°,北纬41.3026°,深度约为550 m,核爆导致发生水平方向位移约3 m,垂直方向位移约1 m.结果表明天基SAR遥感技术,特别是长波段SAR,在地下核试验监测中具有重要的应用价值,可为地下核试验监测提供新思路.

基于Geant4的核孔膜生产模拟研究

利用核反应堆产生的裂变重离子碎片辐照固体薄膜,是生产核孔膜的主要方式之一。为优化反应堆核孔膜生产工艺参数,给核孔膜生产提供理论指导,本文基于Geant4开发了反应堆生产核孔膜的原理性模拟程序,对铀靶在热中子辐照下裂变碎片的生成及出射物理过程开展模拟,并分析计算了不同厚度下铀靶裂变碎片的出射能量、角度分布,从理论上优化了核孔膜生产中的铀靶厚度及固体薄膜厚度。结果表明,铀靶厚度为4μm时裂变碎片出射强度最高;受裂变碎片射程的限制,反应堆生产核孔膜所用的固体薄膜的厚度最大约为8μm。

Developing anti-metallic contamination polyester membranes with nuclear pore technique

Surface contamination by conducting materials,metals in particular,is one of the important causes for electric breakdown of insulators under high voltage.In order to explore the feasibility of nuclear track modification for anti-metallic contamination,polyester membranes with different thickness were bombarded by 32S ions from the HI-13 tandem accelerator of CIAE.The tracks formed on the surface of the membranes were etched under different conditions.The insulating capability of the treated membranes was evaluated by using silver coatings to simulate the surface metallic contamination.The results indicated insulators with the surface modified by nuclear pore technique have an improved capability of anti-contamination of metals.The sample with 144 nm Ag coating is not breakdown under 1000 V.

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。

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.

基于改进核相关算法的钢管塔焊缝特征跟踪研究

针对输电钢管塔纵向焊缝焊接过程中因弧光、飞溅等干扰导致焊缝偏差识别不准确的现状,提出一种基于改进核相关算法的钢管塔焊缝特征跟踪方法。通过图像处理技术得到初始帧焊缝特征点,将最小值图像融合和核相关算法相结合,并采用自适应更新策略,解决了长时间强噪声下核相关滤波模型漂移问题。试验数据表明:该方法能够在强弧光、飞溅干扰下稳定、准确地识别焊缝点,识别焊缝误差均在0.15 mm之内,满足焊接生产实际要求,提高了钢管塔焊接的效率和质量。

核环境中基于时空逻辑推理的作业机器人的轨迹跟踪方法

为了实现核环境中作业机器人(作业车辆)运动轨迹的跟踪估计,提出了一种基于时空逻辑推理的解决方案。首先,通过对作业机器人(作业车辆)建立起简化的运动学模型并考虑操纵员指令先前值和作业车辆先前值,得到一个用11个参数对作业车辆运动轨迹进行解释的状态模型。然后,采用马尔可夫链蒙特卡罗对解空间进行采样,并采用先前的操纵员行为和道路几何形状来有效地定义建议。最后,将作业车辆的一般3D模型投影到每幅图像中,再将其与视频序列的背景/前景图进行比较,同时采用线积分图像实现似然函数,从而从轨迹样本生成作业车辆进入视频序列的一组离散位置。在真实视频序列上的实验结果表明,提出的算法在跟踪误差和轨迹生成方面都优于常用的时序粒子滤波方法。