[en] Some highlights of new developments made in our laboratory at the Atomic Energy Organization of Iran on chemical and electrochemical etching (ECE) of polymer track detectors like polycarbonate (PC) are presented. They include introduction of new ECE chamber systems and methods for production of ECE signs and symbols, and a new versatile ECE chamber (VECE) system for multi-purpose, multi-size, and/or multi-shape detector processing; determination of photoneutron doses in and around high-energy X-ray beams of a 20 MV medical accelerator; verification of the Smythe and Mason equations for ECE of tracks in polymers; ECE of alpha and recoil tracks in PC using PMW, PEW and PEMW etchants; introduction of a novel method using ethylene diamine for treatment of PC detectors with its applications, for example in precision removal of surface layers of PC (e.g. bulk removal rates of about 0.04, 0.15, 0.36, 0.66, and 1.33 mm min^-1 for 60%, 65%, 70%, 75% and 80% ethylene diamine solution (v/v) in water respectively, with no effects on its transparency), and in significant reduction of background track density of PC detectors, in alpha energy discrimination and alpha spectrometry; and development of an image processing system for track counting and measurements; etc. Some main results are reviewed and discussed

[en] A Passive Radon diffusion dosimeter (PRDD) was developed at the Radiation Protection Department of the Atomic Energy Organization of Iran (AEOI) for large scale radon level measurements in Iran. It consists of a plastic cup with a polycarbonate alpha detector in the middle, a plastic top cover with an opening holding a fiberglass filter and a hard aluminium mesh for protection and support. A new design of our multi-chamber system was used for multiple foil etching. The effects of pre-etching and ECE times, chamber volume, filter diameter and foil position inside the chamber were investigated. The optimized geometries include 9.5 cm height, 269 cm³ volume and 2-3 cm filter diameter with the polycarbonate foil mounted in the middle. A sensitivity of 0.05+-0.007 tracks cm^-2/Bq.m^-3 day or 1.96+-0.28 tracks cm^-2/pCi.1^-1 day was obtained at optimized conditions. The characteristics of the dosimeter as well as some preliminary results of indoor radon level measurements for determination of public exposure in 250 houses in different cities of Iran including Tehran, Ramsar, Babolsar and Gonabad are presented. The highest radon levels were found in high natural areas of Ramsar

[en] The electrochemical-etch-foil technique continues to look extremely promising for neutron monitoring of personnel and applications in medicine and research. Some of the most important parameters that must be controlled are presented and discussed. (U.S.)

[en] Direct fast-neutron-induced recoil and alpha particle tracks in polycarbonate films may be enlarged for direct visual observation and automated counting procedures employing electrochemical etching techniques. Electrochemical etching is, for example, carried out in a 28% KOH solution at room temperature by applying a 2000 V peak-to-peak voltage at 1 kHz frequency. Such recoil particle amplification can be used for the detection of wide neutron dose ranges from 1 mrad to 1000 rads or higher, if desired. 5 claims

[en] A new versatile electrochemical etching ECE chamber (VECE) system is introduced in which the effective electrochemically etched area can have variable sizes and/or shapes required using templet etching. The flat rubber washers act as templets and holders of the etchant, and control the size and shape of the effective etched area of the detector which can be of various shapes and sizes desired. The system was operated in two operation modes A and B in which the both sides and one side of the detector were etched respectively. Detectors with etched areas having diameters from 1 to 18 cm have also been successfully etched by this system. Multi-chambers have been also designed using this principle for larger-scale multi-detector processing. The effects of etching area and time on the current through the detector have also been studied

[en] In the present study, the hydrogenation of m-nitrotoluene to m-toludine has been investigated in a three phase slurry reactor, using Raney Nickel as the reaction catalyst. It has been observed that under appropriate conditions both internal and external mass transfer resistances can be eliminated. By applying the Elegy-R ideal mechanism the overall rate of reaction has been presented. The latter has been shown to be of pseudo first order with respect to nitrotoluene concentration. The apparent activation energy for the reaction has been determined as 35 kJ/g mol. Finally, a comparison has been made between the experimental results and those predicted from the reaction rate model

[en] To broaden the registration energy range from 1.5 MeV up to about 5 MeV under one single electrochemical etching (ECE) processing of Lexan polycarbonate at about 27 deg. C with the aim of reducing the background, and the ECE time, etc., methanol (CH₃OH) was added as a mixture with PEW (a mixture of potassium hydroxide, ethanol, and water), under optimised conditions. Registration of alpha particle energies from 0.3 MeV up to about 2.8 MeV in a short etching duration was possible by the use of PEWEG solution (a mixture of potassium hydroxide, ethanol, water, and ethylene glycol) as etchant, under optimised conditions. (author)

[en] Recently, a new powerful dyed electrochemical etching track (DYECET) method, has been produced at the National Radiation Protection Department of the Atomic Energy Organization of Iran. Highly contrasted DYECET'S of neutron-induced recoils in polymers such as polycarbonate and CR-39 have been successfully produced as photon absorbing sites on an unaffected bulk material. Several steps including exposure of the polymer, ECE of tracks, acid sensitization and dyeing were allowed leading to 20% by weight acrylic acid at 75 degree C for 3.5 hours for sensitization and 3% by weight eosin bluish at 95 degree C for 4 hours as optimized values to obtain near 100% DYECET efficiency. The method is powerful for UV and IR spectrophotometry, track counting and track structure studies, but it is a time consuming process. Another similar methods, named Quick DYECET, was developed also in this research making DYECET's within a few minutes using a variety of water and alcohol soluble dyes, without any sensitization step. the new method has many advantages over the above method including simplicity, rapid processing, color variety and dye ability at room temperature. in general, DYECET's under a microscope with reflected light are observed in beautiful colors compared to black under transmission light and with a high resolution for track structure studies and track counting especially at high track densities. the results of the above studies are presented and discussed. (author)

[en] Photoneutron contaminations in and out of high energy X-ray beams of the medical linear accelerator SATURNE 20 (CGR) of the Radiotherapy Department of Omeed Hospital in Isfahan, Iran, have been determined using 250 μm polycarbonate (PC) dosimeters, in strips or in sheets, processed by electrochemical etching (ECE) using specially designed ECE chambers to etch larger sheets. A two dimensional or topographical distribution of neutron contamination was also determined in a full size beam. The neutron dose equivalents (Hn) in the beam of 18 MV X-rays at 80 cm FSD were determined to be linear functions of X-ray dose equivalents (Hx) up to 1400 cSv. The distribution of the Hn at different X-ray doses showed bell-shape profiles with maxima at the isocenter. The ratios of dose equivalents of neutrons to those of X-rays increased as the field size increased having values of 0.22%, 0.28%, 0.31% and 0.37% for field sizes of 10x10, 20x20, 30x30, and 40x40 cm² respectively. Although such neutron dose equivalents can be corrected for patient treatment, it can cause radiation protection problems for workers where the design of the facility is not well planned

[en] An electrochemical etching method for the amplification of fast-neutron-induced recoil particle tracks in polymers was investigated. The technique gave superior results over those obtained by conventional etching methods especially when polycarbonate foils were used for recoil particle track amplification. Electrochemical etching systems capable of multi-foil processing were designed and constructed to demonstrate the feasibility of the techniques for large-scale neutron dosimetry. Electrochemical etching parameters were studied including the nature or type of the polymer foil used, foil thickness and its effect on etching time, the applied voltage and its frequency, the chemical composition, concentration, and temperature of the etchant, distance and angle between the electrodes, and the type of particles such as recoil particles including protons. Recoil particle track density, mean track diameter, and optical density as functions of the mentioned parameters were determined. Each parameter was found to have a distinct effect on the etching results in terms of the measured responses. Several new characteristics of this fast neutron dosimetry method were studied especially for personnel dosimetry using various radiation sources such as nuclear reactors, medical cyclotrons, and isotopic neutron sources. The dose range, neutron energy dependence, directional response, fading characteristics, neutron threshold energy, etc. were investigated