[en] In the systems for fully automatic counting and analyzing of etched nuclear tracks the image processing is made by a videocamera equipped with a microscope. The first automatic track analysis system (DIGITRACK) is reported in which the video signals are processed by a charge-coupled device (CCD) videoreceiver. The photosensitive semiconductor device is a 2.5 cm long line imager of type Fairchild CCD 121HC which converts one row of the picture through a low magnification microscope into 1728 binary signals by a thresholding logic. The picture elements are analysed by a microcomputer interfaced to a PDP-11/40 computer. For pattern recognition and analysis a software procedure is developed. The distribution of track densities and spot areas on the detector surface can be visualized on a graphic display. The DIGITRACK system has been tested for analysis of alpha-tracks recorded by CR-39 and LR-115 detectors. (author)

[en] To manufacture good-quality, uniform CR-39 nuclear track detectors, the polymerization rate should be chosen below a critical value to avoid the development of undesirable thermal gradients and internal temperature fluctuations in the sheet being cast. To improve curing cycles, especially for thick Cr-39 sheets, a computer programme was developed by which the trends of thermal effects under different casting conditions can be studied. The calculations are based on the solution of the one dimensional heat transport equation, taking into account the relations for describing the chemical kinetics of CR-39 polymerization. The empirical parameters available to such calculations were revised. With new 'Dial constants' the critical initial bath temperature (which results in thermal runaway at the central plane of the sheet being cast) was calculated as a function of the CR-39 thickness and IPP initiator concentration. Results are also presented for the temperature profile developing in the depth of cast Cr-39 sheets. (author)

[en] A schematic survey is given on the current relevant problems of the chemical etching (or revelation) of multi-track and single-track events in dielectric solids. The porblems of thresholds, etch-track kinetics and sensitivity are discussed. Some aspects of the research trends and possible new applications of the effects observed here are also considered. (author)

[en] The astrophysically significant yields for the ¹²C(¹²C,⁸Besub(g.s.))¹⁶Osub(g.s.) reaction have been measured at several incident energies between 2.4< Esub(c.m.) (MeV)<6.4, detecting α-particles from the ⁸Besub(g.s.) → α decay in the forward directions by a Mylar shielded Makrofol-E type polycarbonate foil. The α₀ and α₁ groups from the ²⁰Ne+α channels were separately counted at backward angles in the same foil. Compared to the α₀ and α₁ groups the yield for the ¹²C(¹²C,⁸Be)¹⁶O reaction becomes increasingly more important with decreasing energy. The measured angular distributions are indicative of an α-transfer. (author)

[en] The dyed-track method has been successfully developed for cellulose derivatives. The track parameters (width, coloration deepness, contrast, registration sensitivity), however, proved to be very dependent on the detector material and on the track processing conditions. In the authors' previous works optimum conditions were presented mostly for cellulose acetate sheets. In the present work the influence of track processing parameters on the dyed-track formation was studied in Kodak cellulose nitrate detector called CN-85. It is found that in this material optimum dyed-tracks can be produced with using no swelling but with a thermal annealing at 100 deg C for 1 hour after particles irradiation. For sensitization a treatment with 15% HCL at 22 deg C for 20 hours and for dyeing 0.3 wt% Rhodamine-B at 100 deg C for 1 hour proved to be best. For understanding the track dyeing phenomenon the coloration behaviour of electron-irradiated CN-85 detectors was studied. (author)

[en] Neutron-induced autoradiography utilizing the formation of a dyed and/or relief image in polymers was developed. The method is based on the detection of neutron-induced charged particles, via (n,p), (n,α), (n,f) reactions and the neutron capture processes leading to internal conversion and/or β-decay. Irradiated polymers are treated in water containing an organic dye or in pure water for a few minutes to obtain a dyed and/or relief image, resp. The fluence of charged particles required to produce a dyed image is between 10¹¹-10¹² cm^-2 which is one order of magnitude less than that for a relief image. Various procedures based on utilization of optical and electron microscopy for contrast enhancement were developed. The techniques were applied to image boron, uranium and gadolinium in solids. Samples were irradiated in the core of a nuclear reactor. The required thermal neutron fluence was between 10-¹⁴-10¹⁶ cm^-2. (author)

[en] Recently, a new method for electrochemical etcing of fission and alpha-tracks in thin aluminized plastic detectors was proposed by Tommasino et al. By using the new ECE-method, the electirc-tree-induced perforations through nuclear tracks in plastic foils are non-shorting with aluminium at positive polarity, due to an insulating anodic oxid formation. Therefore, a fast dissolution of the aluminium layer by basic electrolyte can be avoided. Authors have studied the main trends of the growth of mean diameter of spots dissolved around fission tracks in aluminized PET foils as a function of the strength of electric field, frequency of voltage and time of etching in 30% KOH, with using both DC and AC voltages and without using field. it is proved that the electric field greatly enhances the rate of etching along the tracks. With irradiation under vacuum a considerable delay in spot appearance is observed. This effect can be partially reduced by using a regeneration period in air after irradiation. The spot diameter distribution obtained by the new ECE-method can be described by the sum of two curves of lognormal distribution, corresponding to the light and heavy fission tracks. (author)

[en] There is a growing interest in collection of data concerning human exposures to naturally occurring alpha-emitting radionuclides (e.g. in mines, dwellings, building materials, industrial wastes, coal fuel cycle, water supply, soil, plants, etc.). Most of such studies are incomplete for the following reasons: in radon measurements the contribution of thoron is generally neglected, the determination of equilibrium factor is complicated or not possible at all, short- and long-term concentration fluctuations cause difficulties in obtaining representative mean values, the plate-out effect is generally not taken into account. A variety of simple methods were studied that could be used to overcome some of these difficulties by using cups equipped with two or more alpha-sensitive nuclear track detectors. A theoretical foundation of the quantitative measurements with such devices is presented. Experimental data are reported on radon, radon daughters and thoron concentrations measured by multi-detector devices in cave soil gas and in air of Hungarian dwellings. (author)

[en] Track diameter as a function of particle fluence is given for electrochemically etched fission fragment tracks. It is shown that high particle fluences decrease the development capacity of electrochemically etched tracks. Therefore the dependence of sensitivity on particle fluence was studied for polyester and poly(allyl diglycol carbonate). Continuously decreasing sensitivity was found even in the case when track overlap did not occur. An idea for correct interpretation of the response is suggested. (author)

[en] Activity concentration distributions of long-lived alpha-emitters in aerosol samples are analysed by high-resolution autoradiography in CR-39. A study of the alpha-activity attached to aerosols of different particulate sizes separated by a cascade impactor is also performed. It is found that in the majority of samples, the alpha-activity can be dominantly related to the presence of ²¹⁰Po produced by its beta-active precursor ²¹⁰Pb. Two methods have been applied, the analysis of alpha-decay properties by means of autoradiographs taken at different post-sampling times, and spectroscopical study of individual alpha-tracks and track clusters by a method developed by the authors for high-resolution alpha-energy determination. In the latter the parameters to be measured are the major axis of surface track opening, the diameter of etched out track end, the total length measurable on the surface along the projected track, and the thickness of layer etched away from the detector surface. (author)