Studies on Ion Emission from the Plasma Focus Device by Using Ion Collector and Track Detector

Ion beam emission from a neon gas filled plasma focus device has been studied by using ion collector and solid state nuclear track detector. The neon ion beam emission is found to be highly pressure dependant and it is maximum at a pressure of 0.3 Torr. The maximum ion energy at 0.3 Torr is estimated to be 1 MeV. Preliminary results on solid state nuclear track detector indicate the formation of tracks in CR-39 due to exposure of neon ions. The average rim diameter of tracks is measured to be 4.35 μm and the number of track is of the order of 10¹⁰ track/m².     

固体核径迹探测器的最新进展

本文介绍固体核径迹探测器近几年来的主要进展,如发现α反应径迹、合成CR-39-SO_2、气泡损伤探测法,以及在各领域中应用的新进展。     

PETP固体径迹探测器的性能研究

报道了惭烯对苯二酸醌固体核径迹探测器对裂变碎片记录性能的实验研究。在改变温度、蚀刻时间和蚀刻液浓度等条件下测量了裂变碎片迷平均直径的变化。实验结果表明：蚀綮 变化对裂变碎片径迹的影响最大，而浓度和蚀刻的影响不大。同时用低能＾１６Ｏ重离子辐照ＰＥＴＰ探测器，并得到了它的标定曲线。     

A track detector technique for determining ion source emission profiles

Solid state nuclear track detectors have been used to directly measure for an ion source the beam emission cross sections along the ion beam trajectory. Results are demonstrated for an ion source of the surface ionization type using solid source materials to obtain ¹⁴⁷Sm or ⁶Li isotopes. Cellulose nitrate LR 115 was used as the detector to register the alpha tracks from the radioactive decay of the implanted ¹⁴⁷Sm and from the ⁶Li (n, α) reaction induced by thermal neutrons in a nuclear reactor.     

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-contaminatiun of metals.The sample with 144 nm Ag coating is not breakdown under 1000 V.     

核乳胶中质子径迹计算机辅助识别方法研究

为克服核乳胶质子径迹人工判读的缺点,研究了一种计算机辅助识别的方法。该方法中,对由显微镜系统获取的核乳胶图像序列依次经组合式滤波器滤波、多阈值二值化、径迹点筛选、径迹点去冗余处理后识别出图像序列中的径迹点,经径迹重建从获取的径迹点中重建出反冲质子径迹。利用该方法从经14.9 MeV中子束辐照的核乳胶中提取出反冲质子径迹,并将提取的径迹与人工判读方法提取的径迹进行了比较,结果基本一致。该方法将为核乳胶质子径迹自动判读系统的开发和核乳胶应用于脉冲中子束能谱测量实验奠定重要技术基础。     

Application of Alpha-Track Method to Tritium Production Rate Measurements

The α-track method with a solid state nuclear track detector was used for the measurement of tritium production rates (TPR). Cellulose nitrate track detectors (Kodak LR-115) with Li-containing radiators were placed in a simulated fusion blanket of a Li₂O slab assembly with a Be layer and irradiated by D-T neutrons. After chemical etching, the etched-through tracks in the detectors were counted. Lithium metal was the most suitable radiator to distinguish tracks formed by α-particles of the LI(n, α)T reaction from the background. The experimental results agreed well with the calculations. This shows that the indirect α-track method is reliable in estimating TPR distribution.     

空间重离子的鉴别

采用地面加速的重离子模拟空间重离子标定了CR－39固体核径迹探测器，通过物理分析和计算方法获得了一个数学表达式，这样就可以通过CR－39固体核径迹探测器上径迹的测量进行离子鉴别和能量估计。     

Discriminative detection of deposited radon daughters on CR-39 track detectors using TRIAC II code

A method for detecting deposited ²¹⁸Po and ²¹⁴Po by a spectrometric study of CR-39 solid state nuclear track detectors is described. The method is based on the application of software imposed selection criteria, concerning the geometrical and optical properties of the tracks, which correspond to tracks created by alpha particles of specific energy falling on the detector at given angles of incidence. The selection criteria were based on a preliminary study of tracks’ parameters (major and minor axes and mean value of brightness), using the TRIAC II code. Since no linear relation was found between the energy and the geometric characteristics of the tracks (major and minor axes), we resorted to the use of an additional parameter in order to classify the tracks according to the particles’ energy. Since the brightness of tracks is associated with the tracks’ depth, the mean value of brightness was chosen as the parameter of choice. To reduce the energy of the particles, which are emitted by deposited ²¹⁸Po and ²¹⁴Po into a quantifiable range, the detectors were covered with an aluminum absorber material. In this way, the discrimination of radon’s daughters was finally accomplished by properly selecting amongst all registered tracks. This method could be applied as a low cost tool for the study of the radon’s daughters behavior in air.     

固体核径迹研究进展

介绍最近几年固体核径迹研究取得的主要进展，包括：径迹形成机制和探测方法研究固体核径迹在核物理、高能和相对论重离子核反应，原子物理、空间科学、宇宙射线探测、地学、测氡和核孔膜等领域的应用。     

Microscopic model for chemical etchability along radiation damage paths in solids

It would be very interesting to develop a picture about removal of atoms from the radiation damaged paths or latent nuclear tracks and undamaged bulk material in track detectors. Here, theory of chemical etching is described briefly and a new model for chemical etching along radiation damaged paths in solids is developed based on basic scientific facts and valid assumptions. Dependence of chemical etching on radiation damage intensity and etching conditions is discussed. A new parameter for etching along radiation damaged paths is introduced, which is useful for investigation of relationship between chemical etchability and radiation damage in a solid. Results and discussion presented here are also useful for further development of nuclear waste immobilization.     

Computer Analysis of Tracks in Nuclear Emulsion Utilizing Digitized Video Scan

A system has developed to make density measurements on particle tracks in nuclear emulsions. The output signal of a videcon viewing the track through a microscope is digitized to detect developed grains in the emulsion. This digitized information is transferred in real time to a computer which selects grains falling in the track and sums their volumes and computes parameters related to their spatial distribution. Analysis of tracks at arbitrary angles is accomplished by rotating the track image in the focal plane with a Pechan prism and by driving the focal plane through the emulsion while taking data.     

Thermal annealing of nuclear tracks in polycarbonate plastic

Thermal annealing, or fading, of latent tracks in a polycarbonate plastic nuclear track detector is investigated. An empirical expression for fading of tracks of relativistic uranium ions is determined, and its form is physically interpreted.     

固体核径迹探测器在中子辐射监测中的应用

介绍固体核径迹探测器近年来在中子辐射监测中的主要进展,其中包括发现CR-39径迹探测器及其主要性能,以及监测中子剂量的方法与应用。     

Analysis of interaction tracks in a stacked film track detector

In a previous paper we presented a method to analyze the data in a stacked film track detector and obtained a nuclear charge distribution for the incident heavy charged particles in cosmic rays.In the course of the analysis, several events of nuclear interaction were found. The present paper presents a method to analyze these interaction tracks by using the results of previous analysis for ordinary (non-interacting) tracks.     

On the long standing question of nuclear track etch induction time: Surface-cap model

Using a systematic set of experiments, nuclear track etch induction time measurements in a widely used CR-39 detector were completed for accessible track-forming particles (fission fragments, 5.2 MeV alpha particles and 5.9 MeV antiprotons). Results of the present work are compared with appropriately selected published results. The possibility of the use of etch induction time for charged particle identification is evaluated. Analysis of experimental results along with the use of well-established theoretical concepts yielded a model about delay in the start of chemical etching of nuclear tracks. The suggested model proposes the formation of a surface-cap (top segment) in each nuclear track consisting of chemically modified material with almost same or even higher resistance to chemical etching compared with bulk material of the track detector. Existing track formation models are reviewed very briefly, which provide one of the two bases of the proposed model. The other basis of the model is the general behavior of hot or energised material having a connection with an environment containing a number of species like ordinary air. Another reason for the delay in the start of etching is suggested as the absence of localization of etching atoms/molecules, which is present during etching at depth along the latent track.     

Determination of alpha-particle track depths in CR-39 detector from their cross-sections and replica heights

A challenging task in the application of solid-state nuclear track detectors (SSNTDs) is the measurement of depths of the tracks. One approach involves breaking and polishing the side of SSNTDs to reveal the cross-sections of the tracks for direct measurements. Recently, surface profilometry was used to measure the heights of the replicas of alpha-particle tracks to give the track depths. In the present work, systematic comparisons among the track depths for alpha-particles with normal incidence and different incident energies were made for these two methods. After irradiation, the detectors were etched in a 6.25 N aqueous solution of NaOH at 70 °C. Both long etching time of 15 h (to produce spherical-phase tracks) and short etching time from 1 to 8 h (to produce sharp-phase tracks) were used. Good agreement was achieved between the two methods for spherical-phase tracks but not for sharp-phase tracks. It has been found that the surface profilometry method only works for replicas for spherical-phase tracks. Replicas for sharp-phase tracks are easier to collapse or deform, so the surface profilometry method may not give correct results.     

Thermal annealing of fission tracks in synthetic apatites

Synthetic analogues of poor-silicated natural apatites have been doped with uranium. These minerals have been irradiated with a thermal neutron dose in the aim to induce the ²³⁵U fission and to obtain a fission track population. Thermal annealing experiments have been performed on the fission track population and allow us to compare the ability of the synthetic minerals to anneal such nuclear damages with their natural analogues. The thermal of the fission tracks in the synthetic minerals need more time and/or higher temperature to reach the same annealing rate as in the natural analogues. The alpha damage present in the natural analogues seems to enhance the thermal annealing of fission tracks.