面阵探测器的像点亚像素定位研究

面阵探测器可直接探测点目标图像的位置，但其定位精度受到探测器分辨率的限制。因此，亚像元精度技术得到了发展。它是利用目标像点的灰度分布特性，通过内插细分算法，确定出像点位置。可将定位精度提高1—2个数量级。本文介绍了几种实现目标像点亚像素定位的内插细分算法。对它们的计算公式、特点进行了分析，并进行了实验验证。     

Alpha particle absorption and inclined incidence track parameters evaluation in plastic detectors

In this work the use of our recently constructed irradiation chamber was involved in the current experiments. The absorption of alpha particle in air has been studied through a set of experiments in which the stopping power has been measured. A comparison between the calculated values and the present experimental results is given and a good agreement has been found. Critical angle (θ_c) determination has been carried out using two different techniques, via indirect and direct measurements, under different etching conditions and at various alpha energies. An empirical fit of θ_c−h (h is the removal thickness layer) dependence has been calculated and found to work well in the studied h ranges. Also, the inclined alpha tracks parameters of energies between 1.0 and 5.0 MeV have been studied. Results can be successfully applicable in alpha autoradiography studies and detector efficiency determination for track registration in plastic recorders.     

Ageing of AgCl/Cd nuclear track detectors monitored by luminescence spectroscopy

Abstract

Solid-state nuclear track detectors, made of Cd doped AgCl crystals, are commonly prepared by rolling into the form of thin foils. Subsequent long-term relaxation is however needed to obtain good quality tracks. The present communication shows for the first time that this detector “ageing” is reflected in lowtemperature (77 K) luminescence spectra. Maximum of the emission band shows a slow (lasting for ～ 100 hours) blue shift, the magnitude of which (as much as 25 nm) depends on the compression ratio caused by the rolling. The shift is believed to be due to the rearrangement of Cd⁺⁺ ions around freshly introduced dislocations. This finding opens the possibility of monitoring non-destructively the process of detector ageing and to determine the minimum time required for saturation.     

Design and implementation of an array of micro-electrochemical detectors for two-dimensional liquid chromatography—Proof of principle

Simultaneous two-dimensional liquid chromatography (2D-LC) is an implementation of two-dimensional liquid chromatography which has the potential to provide very fast, yet highly efficient separations. It is based on the use of time × space and space × space separation systems. The basic principle of this instrument has been validated long ago by the success of two-dimensional thin layer chromatography. The construction of a pressurized wide and flat column (100 mm × 100 mm × 1 mm) operated under an inlet pressure of up to 50 bar was described previously. However, to become a modern analytical method, simultaneous 2D-LC requires the development of detectors suitable for the monitoring of the composition of the eluent of this pressurized planar, wide column. An array of five equidistant micro-electrochemical sensors was built for this purpose and tested. Each sensor is a three-electrode system, with the working electrode being a 25 μm polished platinum micro-electrode. The auxiliary electrode is a thin platinum wire and the reference electrode an Ag/AgCl (3 M sat. KCl) electrode. In this first implementation, proof of principle is demonstrated, but the final instrument will require a much larger array.     

Use of phosphate glass detectors for study of curium-242 cluster radioactivity

The effect α particle fluences (3 × 10³−2 × 10¹⁵ cm ⁻²) on properties of the two types of phosphate glass detectors with different compositions was studied. It was shown that the registration properties of glass detectors depended on the α particle fluence, spatial distribution of the α particle paths, and glass type. The critical α particle fluences, above which the detector properties changed, were determined.     

Particle detection properties of charge coupled devices

A detailed quantitative analysis of particle events observed in Charge Coupled Devices (CCDs) requires the knowledge of particle detection properties of the employed CCDs such as the detection threshold for energy deposition, efficiency for different kinds of radiation and the relation between the signal and the deposited energy inside the sensitive volume. For this purpose the CCD-chip was described by a simple geometrical model containing the effective thicknesses of the p-n semiconductor junctions dj and a covering dead layer d_T above them as parameters. The corresponding geometrical quantities were experimentally estimated to be 1.3 μm and 0.9 μm respectively by using different kinds of radiation.     

Monte Carlo simulation of GM probe and NaI detector efficiency for surface activity measurements

This paper deals with the direct measurement of total (fixed plus removable) surface activity in the presence of interfering radiation fields. Two methods based on Monte Carlo simulations are used: one for a Geiger–Muller (GM) ionisation probe and the other for sodium iodide (NaI) detector with lead collimators; equations for the most general case and the geometry models for Monte Carlo simulation of both (GM and NaI) detectors are employed. Finally, an example of application is discussed.     

Non-contact charge temperature measurement on industrial continuous furnaces and steel charge emissivity analysis

Continuous furnaces are commonly used for steel billet reheating before a rolling operation. It is necessary to perform a number of measurements to set-up and operate the optimization system of the furnaces correctly. A charge temperature measurement using infrared detectors can be one of the usable measurement techniques. This non-contact measurement method is based on the detection of infrared radiation emitted from a measured surface. The radiation intensity depends on the surface temperature and emissivity, which is one of the most important parameters for infrared measurements. Advantages of the non-contact temperature measurement, as well as some problems regarding the surface emissivity, are presented. The direct steel billet temperature measurement procedure using infra-red detectors, emissivity determination procedures, and example results are introduced. It is shown that steel emissivity can vary from approx. 0.17 to 0.8, depending on the surface state, scale formation, and wavelength interval. These problems are critical for the charge temperature measurement using the infra-red detectors, and are discussed in this paper.     

Comparison of responses of LR-115A, CR-39 and PM-355 track detectors to pulsed low-energy proton streams

The paper concerns applications of LR-115A, CR-39 and PM-355 solid-state nuclear-track detectors (SSNTDs) for investigation of pulsed fluxes of protons below 300 keV. The proton streams were generated by the RPI-IBIS device operated with hydrogen puffing [Baranowski et al. 2000. Studies of hydrogen discharges in RPI-type devices with different electrode configurations. Czech. J. Phys. 50 (Suppl. S3), 101–107]. To perform ion mass- and energy-analysis, a Thomson mass-spectrometer equipped with a special input system and exchangeable detectors was used. A quantitative analysis of proton tracks upon Thomson parabolas was performed by means of an optical microscope equipped with a CCD camera. It made possible to measure proton tracks and to determine their statistics. The paper presents proton energy spectra recorded with the selected detectors, and responses of these detectors to protons of energy from about 30 to 300 keV. The results are important for verification of detector characteristics and for measurements of protons at different experimental conditions.