Application of CR-39 track detectors for corpuscular diagnostics of high-temperature plasmas

Solid State Nuclear Track Detectors (SSNTDs) have been used for corpuscular diagnostic in numerous high-temperature plasma experiments. This paper presents different applications of the detectors mentioned above, particularly in nuclear fusion investigations. Some new projects and proposals of the use of such detectors in large-scale plasma experiments, e.g. tokamaks, and laser-fusion facilities are demonstrated. To use the SSNTDs in the optimal way and to determine their detection characteristics, detailed calibration studies of the selected plastic detectors (CR-39, PM-355, PM-500, PM-600) have been performed at IPJ for several years. To carry out calibration measurements of these detectors, ion beams from different accelerators were applied. The paper presents detection characteristics, i.e. track dimensions as a function of ion energy, atomic number and etching time.     

Calibration of CN and CR-39 track detectors for measurements of fast deuterons and nitrogen ions

The paper reports on the analysis of responses of CN-type films and CR39-plastic nuclear track detectors (NTDs) to fast deutrons and nitrogen ions emitted from high-current Plasma-Focus (PF) facilities, as operated at SINS and INFIP. In order to separate the deutrons and nitrogen ions of different energy, the use was made of a Thomson-type mass-spectrometer adapted to measurements within dense plasma streams. Deutron and ion parabolaen were registered the CN-80 and CN-LR115 films as well as with the CR39 plastic NTDs, which were undergone routine etching procedures. On the basisof known characteristics of the spectrometer applied energy- and mass-scales for the obtained ion paraboale were determined. Using an optical microscope, a detailed analysis of track dimensions was performed in chosen points along the registered parabolae, and the calibration diagrams (i.e. a track diameter for the chosen ion energy and different etching times) were determined. Results of the calibration procedure, after comparing with other calibration data obtained with conventional particle accelerators, may be applicable for measurements of fast deutrons (i.g., in nuclear fusion experiments) and energetic nitrogen ions (i.g., in some plasma- and ion-facilities used for technological applications).     

Low-energy ion measurements by means of CR-39 nuclear track detectors

The paper presents an additional acceleration system, used to shift up an ion energy spectrum by 20 keV, and some examples of the ion parabolas registered by means of a Thomson-type spectrometer within the rod plasma injector (RPI-60) facility, designed for plasma physics and application studies. The use of the described acceleration system and CR-39 track detectors has enabled the registration of ions of energy above 20 keV to be performed. It made possible to measure the ion (e.g. deuteron) energy spectrum more exactly in the low-energy range, what is important for the determination of ion emission characteristics.     

LiF:Mg,Ti (MTT) TL detectors optimised for high-LET radiation dosimetry

The properties of LiF:Mg,Ti (distributed as, e.g., TLD-100 or MTS-N), the most frequently used thermoluminescent detector, have been optimised for measurements of sparsely ionising radiation (gamma rays), typically encountered in radiation protection or clinical dosimetry. However, these detectors need also to be applied in conditions of mixed-field dosimetry with a high-LET component, such as those encountered in heavy ion beams or in space.

At the Institute of Nuclear Physics in Kraków a new type of LiF:Mg,Ti detector (named MTT) has been recently developed through modification of its dopant composition. This composition is intended to increase the detection efficiency after a dose of high-LET radiation. The concentration of dopants in the MTT material is: C_Mg=50 ppm, and C_Ti=120 ppm, i.e. about a three times less of magnesium and about 10 times more of titanium content, compared with the standard MTS-N. The MTT TL detectors feature an increased relative efficiency to high-LET radiation, which for 5 MeV alpha-particles is about twice that of standard LiF:Mg,Ti. The response of MTT detectors has been studied in charged particle beams of the HIMAC accelerator in Chiba, Japan and in Dubna, Russia. The main foreseen application of MTT detectors are dose measurements in space. The dose after high-LET exposure can be estimated from the difference of the response of MTS and MTT detectors. In the near future MTT detectors will be applied in the “Matroshka” experiment. Within this experiment a specially constructed human phantom will be exposed in free space (outside the International Space Station) for 1 year. The phantom will incorporate a few thousand measuring points enabling radiation doses to particular organs to be determined.     

Application of CR-39 detectors for study of corpuscular emission from Prague capillary pinch

The paper describes experimental studies of the corpuscular emission from fast Z-pinch discharges, which were performed within the CAPEX capillary pinch facility in Prague, Czech Republic. Time-integrated measurements were carried out with an ion pinhole camera equipped with CR-39 nuclear track detectors. Irradiated detectors were etched at the standard conditions, and developed tracks were analysed with an optical microscope coupled with a CCD camera. It was found that the fast capillary discharges emit strong corpuscular streams. On the basis of the optical analysis of the etched detectors it was estimated that the time-integrated particle flux, at the distance of 20 cm from the collimator outlet, was about 3.5×10⁷ particles/cm²/pulse. Particular attention was paid to analysis of ion-track photos, which were obtained by means of an electron microscope. Details of the ion micro-craters have been observed in the photos of fractures of the CR-39 detectors after their 7 h etching.     

Development of methods for multidimensional measurements in the optical investigation of surface

The problems of developing methods for multidimensional (multichannel) data acquisition as applied to the optical study of the surface are considered. Unlike conventional methods of transition to multidimensional measurement, which employ mechanical scanning, the use of new-type instruments that allow for coordinate-sensitive and time measurements are discussed. Both the sensitive elements (detectors) and the instruments (hyperspectrometers) created for multidimensional coordinate-spectrum-time measurements are described. The application of hyperspectrometers makes it possible to increase manyfold the information content of measurements. The fluorescence of dye molecules deposited on the surfaces of germanium and silicon preirradiated by a laser beam is studied. The scattering spectra from these samples are examined.     

THz radiation sensors

In the paper, issues associated with the development and exploitation of terahertz (THz) radiation detectors are discussed. The paper is written for those readers who desire an analysis of the latest developments in different type of THz radiation sensors (detectors), which play an increasing role in different areas of human activity (e.g., security, biological, drugs and explosions detection, imaging, astronomy applications, etc.). The basic physical phenomena and the recent progress in both direct and heterodyne detectors are discussed. More details concern Schottky barrier diodes, pair braking detectors, hot electron mixers, and field-effect transistor detectors. Also the operational conditions of THz detectors and their upper performance limits are discussed.     

Simultaneous multiple synchronous detection in photoacoustic measurements

Photoacoustic detection of multiple compounds can be done in at least a few ways. One of the simplest methods is performing sequential measurements at selected wavelengths at which the compounds under detection would absorb. The main disadvantage of the method is relatively long time of the measurements – proportional to the number of wavelengths at which the measurements are performed. Time of the measurements can be significantly shortened e.g. by means of a simultaneous detection at a few light wavelengths, intensity of each modulated with a different frequency. Typical approach to implementation of such a setup requires use of a corresponding number of synchronous detectors. The paper presents a solution based on a single A/D converter and programmable logic circuit that implements high precision, simultaneous, synchronous detection of a few signals of different frequencies. The discussed equipment is capable of simultaneous recording of shape of all these signals independently. Strongly reduced hardware concept results in low cost and small size of the device.     

Diffuse surface calibration method to improve accuracy and dynamic range of aerosol elastic light scattering measurements

A new method to calibrate detectors for elastic light scattering (ELS) measurement based on diffuse scattering from a Lambertian surface is presented. The method produces a calibration signal that is approximately seven orders of magnitude larger than a propane gas Rayleigh scattering calibration. The method also allows for calibration of detectors such as photodiodes, which are not sensitive enough to detect Rayleigh scattering for calibration but possess characteristics desirable for the measurement of soot ELS. Since the method is only suitable for backward scattering calibrations, transfer of calibration data from a backward- to a forward-oriented detector is accomplished with a secondary laser and integrating sphere. In demonstration experiments, calibration constants for photomultiplier tube (PMT) detectors obtained using both Rayleigh scattering and diffuse surface scattering agreed within experimental uncertainties as did measurements of in-flame scattering coefficients obtained with PMTs and photodiodes. However, achievable uncertainties with the diffuse-surface calibration approach were significantly reduced. More importantly, by enabling the use of photodiode detectors in ELS measurements, the new method facilitates operation at higher photon fluxes resulting in improved signal-to-noise ratios, reduced influence of photon shot noise, and the ability to achieve higher dynamic range in transient measurements.     

Application of solid-state nuclear track detectors for studies of fast ion beams within PF-1000 and other plasma-focus facilities

The paper presents results of studies of the fast ion emission from two plasma facilities: PF-1000 and PF-II. The measurements were carried out mainly with solid-state nuclear track detectors (SSNTDs). To register ion mass- and energy-spectra, obtained when primary ion beams are deflected by magnetic and electric fields of a Thomson-type spectrometer, the SSNTDs plates were installed inside the analyzer. To measure ion angular distributions the SSNTDs were located within the main discharge chamber, at different angles to the electrode axis. The SSNTDs were also applied to register ion beam images formed within an ion pinhole camera, and to determine a spatial location of the fast ion sources.     

Laser plasma monitored by silicon carbide detectors

The excellent physical and chemical properties and the radiation hardness of silicon carbide (SiC) render this material particularly suitable for the realization of radiation detectors. In this paper we describe the main properties of SiC and the processes needed to realize good performance detectors. To this purpose, we made SiC Schottky diodes that were electrical characterized by using different techniques. In order to test the radiation hardness, the diodes were irradiated with different ion beams and the analysis of the electrical measurements allowed to identify the defects responsible of the device degradation. These detectors have been used to monitor the multi-MeV ions of the plasma emitted by irradiation of various targets with 300-ps laser at high intensity (10¹⁶?W/cm²). These measurements highlighted that the use of SiC detectors enhances the sensitivity to ions detection due to the cutting of the visible and soft ultraviolet radiation emitted from plasma. The small rise time and the proportionality to ion energy evidence that these detectors are a powerful tool for the characterization of ion generated by high-intensity pulsed laser.     

On the formation of heavy ion latent tracks in polymeric detectors

Three kinds of polymeric track detectors have been examined by ESR spectroscopy following heavy ion or energetic electron bombardment: (1) Typical nuclear track detectors: makrofol, kapton, terphane; (2) Polymers whose radiolysis under γ-rays or electron beams is well established: PMMA, PE, PP; (3) Polymers in which etchable tracks have not so far been observed e.g. teflon. The influence on the various ESR spectra of the radiation dose, of annealing or chemical etching treatments leads us to suggest that existence of heavy ion latent tracks might be correlated with the formation of “carbon-like” radicals such as produced in polymer pyrolysis.     

Design and tests of Cherenkov detector for measurements of fast electrons within Castor tokamak

The paper concerns a novel diagnostic technique applicable for indirect, spatially resolved measurements of energetic electrons generated inside tokamak-type facilities. Such measurements can be performed making use of the Cherenkov-effect induced by fast electrons inside a transparent medium (radiator). A construction of the Cherenkov-type detectors adapted for tokamak research is presented and preliminary results of the first measurements carried out within the CASTOR tokamak operated at IPP in Prague are reviewed.     

在改进的等离子体源质谱仪中加入电光离子检测器

从整个质谱学的历史来看，阵列检测器一直用来进行同时和连续的质谱测量研究。利用阵列检测器获取多道数据的好处已为人们所熟知，这包括较大的占空因素、供助比值和内标技术改善的精度以及对快信号瞬变过程较好的定量分析，由于有这些好处，多种基于阵列检测器的测量仪器得到开发，包括光学的和质谱仪，本文描述配备多道电光离子检测器的等离子体源Mattauch-Herzog质谱仪改善了性能，所有的实验均采用一个辉光放电源，过去报道的这台质谱仪的基于阵列检测器的数据在质量方面受到严重的局限,谱峰形状和分辨率都极差。本文将介绍与阵列检测器有关的几个性能指数，这包括灵敏度、分辨率、谱峰形状以及同位素灵敏度。所有这些性能指数都得到明显的改善。阵列检测器性能方面有待解决的问题包括对磁场的敏感性以及在整个阵列表面灵敏度缺乏均匀性。     

The low-pressure focal plane detector of the MAGNEX spectrometer

The focal plane detector of the MAGNEX large acceptance magnetic spectrometer is presented. It is based on a large low-pressure gas-filled tracker followed by a wall of silicon detectors to stop the particles. It has been designed for the stringent requirements from the ion optics and the foreseen use with heavy ions. The performances of the device are demonstrated using 4MeV/u oxygen beams. The results of the tests are described and discussed in view of the application of the particle identification and trajectory reconstruction techniques to recover the kinematic properties of the reaction products. They demonstrate the suitability of such detector in a wide range of experiments where low-energy thresholds, large-accepted solid angle, precise momentum measurement and good particle identification are needed.     

High energy heavy ion tracks in bubble detectors

Bubble detectors which are commonly used as neutron detectors have been demonstrated through this study to be good detectors for registration of high energy heavy ion tracks. Large size bubble detectors made in China Institute of Atomic Energy were irradiated to heavy ions Ar and C up to 650 MeV/u and 400 MeV/u, respectively. Very clear features of stringy tracks of high energy heavy ions and their fragmentations are manifested and distinguishable. A single track created by a specific high energy heavy ion is composed of a line of bubbles, which is visible by naked eyes and retained for months wihhout reduction in size. The creation of heavy ion tracks in bubble detectors is governed by a threshold whose essence is approximately a critical value of energy loss rate (dE/dX)_c similar to that of etch track detectors. Ranges of heavy ions in bubble detectors are apparent and predictable by existing formulas. Identification of high energy heavy ions and the applications to heavy ion physics, cosmic rays, exotic particles and cancer therapy monitoring are obviously promising. The experimental and theoretical aspects of high energy heavy ion tracks in bubble detectors as well as the expectable applications are presented and discussed.     

Influence of intensive γ and electron radiation on tracks formation in the PM-355 detectors

Solid-state nuclear track detectors have found wide use in various domains of science and technology, e.g. in plasma experiments. The track detectors used in the fusion-oriented experiments encounter “harsh” conditions (intense X-ray and neutron radiation, heat impact, shock waves and plasma fluxes). Therefore, such detectors should be tested under similar conditions. This paper concerns influence of electron and γ radiation on the track formation in PM-355 detectors. Samples were irradiated with 1.5-MeV protons and ⁴He-ions, and with 5.5 MeV particles. After that they were exposed to γ and electron radiation. Irradiation doses were varied from 100 kGy up to 2000 kGy. The etching was performed in steps, and a bulk etching rate (V_B) was determined versus an absorbed dose of electron and gamma radiation.     

Fast beam collinear laser-rf double resonance

The method and application of fast beam collinear laser-rf double resonance are discussed. Following a short theoretical treatment of the collinear interaction of fast atoms with rf and laser fields, the experimental procedure and some technical details are presented. Selected applications of the method: (i) hyperfine structure and atomicg-factor measurements, and (ii) experimental studies of fundamental aspects of atom-field interactions, are described. prospective applications in nuclear physics experiments are discussed.     

无碰撞等离子体电流片中的低频波

采用两种无碰撞二维三分量不可压缩磁流体力学（MHD）模型，计入电子扰动压力张量效应，研究了电流片等离子体的色散性质和波.由于得到的一般色散关系较为复杂，只解析讨论了电流片的中心区和电子β*e=0两种特殊情况.主要结果如下：(1)在短波区（kdi＞1），存在快磁声 动理学Alfven波和斜Alfven 哨声模，电子磁流体力学模型是足够精确的MHD模型；在长波区（kdi＜1＝，存在Alfven波和离子声波，理想的MHD模型是适用的.（2）电子β*e＝0情况下的结果，显然遗漏了一些波模（如离子声波和快磁声动理 关键词： 电流片 磁流体力学 电子压力张量 色散关系     

An environmental BeO-OSL dosimeter for emergency response

A conceptual design is presented to use measurements of localized absorbed dose in inner cities for production of high resolution maps of the radioactive contamination following a nuclear emergency or radiological attack. The doses are derived from luminescent detectors pre-fixed at places of high importance (e.g. public squares). For such an environmental dosimeter, BeO is used, which can be read out using optically stimulated luminescence (OSL). A suitable casing of black Perspex has been developed to give a sufficiently accurate estimate of the air kerma value at the detector position. The dosimeter is characterized according to light tightness, dose response and angular photon energy dependence. A short overview of the approach for map production is also given.