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.

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).

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.

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.

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.

基于平板扫描仪的氡测量方法研究

CR-39固体径迹探测器因其材料的稳定性、良好的实用性等特点被广泛应用于氡的测量领域。针对现有的商用固体径迹探测器自动测读系统价格昂贵、维护成本及环境要求高的问题,本研究利用平板扫描仪设备,开展固体径迹形态学研究,通过建立基于径迹形态学参数的氡径迹识别法则,实现氡的高效、低成本测量。测量结果表明氡暴露量在500 kBq·h/m^(3)以下时,径迹密度-暴露量曲线呈现良好的线性关系。研究表明,基于平板扫描仪的氡测量方法有望实现氡的高效测量且该测读方法兼顾高效、低成本、环境适应性强的特点。

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.

在生物堆试验中用塑料核径迹探测器作高游离宇宙线重核的辐射生物学研究

本文报道1988年8月首次在中国返回型卫星舱内放置的两个封闭生物堆试验中应用塑料核径迹探测器跟踪定位测量高游离宇宙线重核粒子对植物的辐射损伤情况。在空间诱变育种研究方面得到了令人满意的初步结果。

CR-39固体核径迹探测器用于中子测量化学蚀刻参数的优化

通过实验确定了CR-39固体核径迹探测器用于中子测量的化学蚀刻条件。根据有关资料和经验,对蚀刻结果影响较大的三个因子——蚀刻溶液的浓度(mol/L)、温度(℃)和蚀刻时间(h),采用正交试验法,并对正交试验进行补充和验证;通过对实验结果综合分析比较,在NaOH溶液浓度为5.5mol/L、温度70℃和时间24h的蚀刻条件下,CR-39固体核径迹探测器对中子所形成的径迹轮廓清晰、大小适度,蚀刻效率高,易于识别和测读,能满足中子测量的需要。

搭载水稻种子被空间重离子击中的定位研究

为了探明水稻种子在空间搭载后发生突变的原因,设计了一个“三明治”式的实验系统,采用CR-39固体核径迹探测器来探测空间离子,并利用实验系统中空间离子径迹与水稻种子的相对位置,来确定被离子击中的种子和部位。

固体核径迹自动测量系统及其主要应用

图象分析技术在固体核径迹自动测量中有着重要的作用 ,特别是在径迹参数测量方面更具显著特点。本文阐述了固体核径迹自动计数和参数测量的方法及其主要的应用领域。

亚细胞微观硼浓度测量方法研究

硼中子俘获治疗(BNCT)中亚细胞微观10B的分布对确定细胞凋亡概率和细胞核内的沉积剂量有重要意义。本工作研究采用CR-39固体径迹探测器测量亚细胞结构中10B浓度的方法,通过激光标记、光电镜扫描及图像重建方式获得了生物切片中各细胞器的径迹密度,在ICP-AES宏观测量基础上计算出相应细胞器的10B浓度。实验结果表明,固体径迹探测器与激光标记和电镜扫描结合可实现亚细胞结构中微观10B分布浓度的测量。

热敏智能径迹膜

以N-异丙基丙烯酰胺热敏功能材料为单体，核径迹微孔膜为基材，利用过氧化预辐照接枝技术，研制能控制开关、调节微粒筛分的热敏智能径迹膜。亚微米级接技敏感径迹孔只需极薄的热敏层，溶胀与收缩速度迅速，使对温度开关响应更为灵敏。

CR-39固体核径迹探测器观测方法

针对重离子辐射的CR-39固体核径迹探测器中的微观径迹结构特点和剂量特征研究的必要步骤———探测器观测,从CR-39中粒子潜径迹形成和发展出发,探讨了影响粒子径迹的因素,选取两种径迹观测方法———光学显微镜观测和电子显微镜观测进行对比分析。在此基础上进行了试验,用不同通量的100 MeV Si离子照射CR-39探测器,将实验样品用NaOH溶液(70℃6,.25 N)分别进行6h和5 min的刻蚀。刻蚀后,用光学显微镜和原子力显微镜进行观察,得到了放大的径迹和纳米尺度的微观径迹。此外,局部覆盖刻蚀后用台阶仪进行观测,得到了体刻蚀速率为Vb=1.53μm/h。

用于离子能谱测量的Thom son谱仪设计与数据处理技术

在设计可用于测量质子、α粒子以及其他重带电离子能谱的Thomson谱仪的过程中,研究了带电离子在谱仪电场和磁场作用下的运动轨迹,开发了相应的计算机辅助设计软件。CR39固体径迹探测器作为离子记录介质,离子径迹在记录面呈现抛物线带状分布,研究了由抛物线带状分布回推离子能谱的数据处理方法。

成都市室内氡浓度评价

为摸底成都市各市区室内氡浓度分布,采用固体核径迹探测器进行监测,对测量结果分组归类分析。结果表明成都市区居室氡浓度水平以市内两条隐伏断层为界呈现北高南低的变化规律,各季节室内^(222)Rn浓度变化不大,平均浓度为41 Bq/m^3与世界平均水平40 Bq/m^3相当,未超过我国推荐的标准限值。

基于CR39固体核径迹探测器的低能中子剂量测量方法初步研究

本文给出了一种采用固体核径迹探测器测量低能(0.5 e V以下能量)中子的双片径迹计数方法,利用蒙特卡罗模拟和实验,统计分析了低能中子引起的探测器单位面积径迹密度。结果显示,采用双片径迹计数方法,实现了CR39对于低能中子的响应,可以对低能中子引起的个人剂量进行估算。应用在中子职业个人剂量监测时,有效甄别了背景径迹的影响,因而降低了测量误差,对减小中子个人剂量监测的测量不确定度也是一个可行的方法。

固体径迹探测器测量反应堆功率研究

在零功率反应堆上利用固体径迹探测器直接测量燃料元件内的裂变率，可得到反应堆的功率。同时测量反应堆某位置的热中子通量密度，继而可得到单位功率的热中子通量密度。因此，通过测量该点的任何热中子通量密度即可得到反应堆的运行功率。该方法可以减少与能谱测量有关的修正工作。由于辐照所需的中子通量密度低、时间短，因此与活化法等相比具有明显的优点。