Calibration of PM-355 nuclear track detectors; comparison of track diameter diagrams with track depth characteristics

The calibration diagrams, i.e. track diameters and track depths versus ion energy and etching time, as obtained for PM-355 track detector irradiated with He-ions are presented. The both detector characteristics are compared. The track etch rate is determined by two methods, as a function of the etch pit depth and the ion energy loss.     

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.     

On the question of nuclear track formation in plastic material

A review is given about nuclear track formation in plastic track detectors. The radiation damage of heavy ions around the latent tracks is studied using measurements of radial track etch rates in Å-dimensions.     

Study of spatial structure and energy spectrum of ion beams by means of LR 115A and PM-355 nuclear track detectors

The paper reports on measurements of pulsed plasma-ion streams, as performed with the selected solid-state nuclear track detectors (SSNTD). The ion-beams were produced by an experimental device (RPI-IBIS) equipped with coaxial electrodes (each made of molybdenum rods) and a fast-acting gas valve. The device was operated at 30 kV/44 kJ, with puffing of pure hydrogen or deuterium. The spatial structure of the ion beams was studied with pinhole cameras equipped with replaceable detectors, and ion mass- and energy-spectra were measured with a Thomson spectrometer. To analyse low-energy ions (below the energy thresholds of LR 115A and PM-355 SSNTD) an additional accelerating system was applied. It was observed that ions of energy are emitted in bunches, and the ion flux amounts to at a distance of 30 cm from the electrodes outlet. Energy spectra of protons and deuterons ranged from about 30 keV to about 400 keV. The ion distributions, as recorded by means of the PM-355 and LR 115A detectors, are similar.     

Radon epidemiology and nuclear track detectors: Methods, results and perspectives

An important achievement of nuclear track detectors is that they render it possible to measure a large number of radon concentrations. These are necessary for epidemiological studies aimed to estimate the lung cancer risk due to exposure to radon and its decay products in dwellings. Many case–control studies were conducted in the last 15 years in Europe, North America and China, in order to avoid the uncertainties associated with the risk extrapolation from epidemiological studies on miners exposed in underground mines. In this review paper, the main methodological issues of these studies are introduced: confounding factors, the impact of radon exposure uncertainties on the estimated risk, the retrospective assessment of radon exposure through the measurement of surface concentration on glass objects, the interaction between radon and smoking, statistical methods to analyze data and combine studies, etc. As regards the estimated risk of lung cancer, the main characteristics and results of each study are reported and discussed, together with the results of meta-analyses and, most importantly, of the three recently published analyses that pool 2 Chinese, 7 North American, and 13 European studies. Finally, some conclusions are given and a brief reference is made to ongoing studies.     

Comparison of Makrofol-E and CR-39 as Solid State Nuclear Track Detectors

A comparison of the etching parameters as well as the neutron response for Makrofol-E and CR-39 was considered as solid state nuclear track detectors. The calculated sensitivity for both detectors was compared with the measured one. It is found that CR-39 has higher response to fast neutrons than Makrofol-E. The response increase due to decreasing the rate of layer removed and increasing the etch-pits per unit area.     

Fossil track studies of the Omolon pallasite crystals

The olivine and stanfildite crystals from Omolon pallasite meteorite were selected from some residue and from locations of an about 150 g fragment of that meteorite in the Meteoritic Committee, Moscow, Russia. The radiation age of Amnion pallasite was determined to be about 78 MY The Olivine crystals were mounted in epoxy resin, polished and etched in Krishnaswami solution, modified by adding 30 g per liter oxalic acid. The etching of the olivine crystals was performed in hermetically closed vessels during 36–72 hours at T = 100 ° C. The measured Fe- group track density varies from 3 × 10⁴ up to 2.6 × 10⁵ track. cm⁻². The measure in 12 Fe-group track rich olivine 43 track due to VVH nuclei were found. It means that the depth of ablation of Omolon meteorite does not exceed (8.2 ± 2.1) cm out of preatmospheric surface for the most favourable locations.     

The Effects of Storage on CR-39

The effects of storage temperatures on the track registration of CR-39 as a solid state nuclear track detectors have been investigated. The results show that the storage CR-39 detectors cause partial or complete removal of tracks depending on storaged time and temperatures. The bulk activation energy for CR-39 has been found to be 0.883 eV.     

Nuclear tracks: present and future perspectives

Current research work related to the development of nuclear tracks comprising: (i) fundamental principles (nuclear track physics and chemistry, as well as development of track detectors and the relevant hard- and software), (ii) development of nuclear instruments and methods (etch track radiometers for ions, neutrons and cosmic rays, radon monitoring devices, radiography and fission track dating) is briefly outlined. The paper concentrates on a literature survey of applications of nuclear tracks in (iii) physical sciences (high-energy physics, nuclear physics and earth sciences), (iv) biomedical sciences (radiation protection, environment, cancer therapy), and (v) technological sciences (materials, nano-technology and nuclear technology).

Presently about 350 papers per year are being published in this field. Increased activity is noted in ion track technology (track-made membranes, modern nano-tech methodology including biological and biological-like samples, nano-electrode bio-electrochemistry, bio-magnetic assays and probes). New applications of nuclear tracks in fundamental (possibility of the detection of neutron quantum states in a gravitational field, nucleus–nucleus interactions, search for new chemical super-heavy elements) and applied science (precise measurements of the behaviour of radiation in human tissue in connection with of long term space missions and treatment of cancer) are surveyed, and possible research in the next decades is presented and examined in this review paper.     

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.     

Contribution of Radon Daughters Plated-Out in a Cylindrical Device by Track-Technique

CR-39 plastic nuclear track detector is used to measure the fraction of alpha-particle tracks due to radon daughters activities plated-out on the internal walls of a cylindrical-shaped plastic can. Radium chloride solution is used as a radon source, the exposure time is ranged from 4 hours to 3 days. To assess the percentage of plate-out effect on CR-39 nuclear track detector, two different methods were used. In one experiment, a few circular parallel pairs of CR-39 sheets were hanged in the can device. In the other experiment, the estimation of the plate-out effect has been performed, after exposure to the radon source, by detecting tracks with a second unexposed sheet placed in close contact to the exposed wall and detectors. In the two methods, it was found that the chemically etched tracks related to plated-out activities contribute about 50% of the measured alpha-particles tracks.

Der CR-39 Plast-Kernspurdetektor wurde zur Messung des Anteils an Spuren von Alphateilchen verwendet, die sich von den Radon-Tochterprodukten ergeben und auf den Innenwänden eines zylindrisch gestalteten Plastbehälters abgeschieden haben. Als Radonquelle wurde eine Radiumchlorid-Lösung verwendet und die Expositionszeiten lagen zwischen 4 Stunden und 3 Tagen. Um den Anteil des Abscheidungseffektes in einem CR-39 Spurdetektor zu bestimmen, wurden zwei unterschiedliche Methoden angewendet. In dent einen Versuch wurden einige zylindrische Parallelpaare von CR-39 Folien in den Behälter gehängt. In dent anderen Versuch wurde der Abscheidungseffekt in der Weise ermittelt, daβ nach der Exposition auf die Radonquelle mit einer zweiten nichtexponierten Folie die Spuren bestimmt wurden. Die nichtexponierte Folie war dabei in einem engen Kontakt zur exponierten Wand und den Detektoren. Durch beide Methoden wurde gefunden, daβ die chemiseh geätzten Spuren, die auf die Abscheidimgsaktivitäten züruckgeführt werden können, einen ungefahren Anteil von 50% an den gemessenen Alphateilchenspuren ausmachen.     

Comparative measurements between NTD and GEL detectors for radon gas

Because of the interest in an inexpensive radon monitoring technique and the use of new materials and new methods, this work presents comparative measurements between traditional passive radon detector using nuclear track detector (NTD), and a new method based on the diffusion of radon gas in gels, measuring the quantity of the remainder radioactive solids by the analysis of the gamma radiation from the decay of radon daughters. The methodology of the new detectors is introduced. The preliminary results show a measurable response of the gel material detectors to radon gas. The measurements are compared with those using NTDs CR-39 type for calibration purposes. Both the detection systems, the passive close-end cup system with NTDs and the passive close-end cup gel material detector, were exposed at the same time in the radon calibration chamber to different radon exposition levels from 150 to 3000 Bq/m⁻³.     

Measurement of B concentration through autoradiography images in polycarbonate nuclear track detectors

The determination of the local concentration of boron in the different regions of tissue samples treated by Boron Neutron Capture Therapy (BNCT) could be made through the evaluation of the number of tracks forming autoradiography images. It is necessary to get a “standard” material containing a known amount of ¹⁰B, to correlate the number of tracks and boron concentration, i.e. to be used as a reference.Different systems were tested in order to find a suitable standard. Films made of 2% agarose in boron solutions showed a homogeneous distribution of the ¹⁰B atoms in the material structure. This system is easy handled and its physical properties are satisfactory.On the other hand, a small volume polycarbonate box was designed to contain ¹⁰B solutions of known concentration. This system showed a reduced number of background tracks and a promising behavior in many aspects. There is proportionality between track numbers per surface unit and ¹⁰B concentration, and between track numbers per surface unit and neutron fluence. Experimental results were compared to calculated values through formulas developed for thick samples autoradiography.     

A joint UAB-IReS-IPNO neutron comparison exercise with nuclear track detectors

The response of PN3 and CR-39 personal dosemeters with different configurations, developed by the IReS (Strasbourg), the IPNO (Orsay) and the UAB (Barcelona) groups, is investigated in this study. Both dosemeters were mounted on a water-filled phantom and were simultaneously exposed under different incidence angles (0, 30 and 60) to the following: (i) three ISO neutron sources (²⁴¹Am-Be, bare ²⁵²Cf and moderated ²⁵²Cf with Cd shielding), and (ii) two realistic neutron sources (SIGMA and moderated ²⁵²Cf) at the IRSN (Cadarache) facilities. After irradiation, the plastic detectors were etched and evaluated according to local routine procedures and corrections for the effect of source-to-detector distance were taken into account. A comparison of the average background, the minimum detectable dose equivalent and the field calibration factor is performed as well.     

Single-sheet identification method of heavy charged particles using solid state nuclear track detectors

The theoretical and experimental investigations of the penetration of charged particles in matter played a very important role in the development of modern physics. Solid state nuclear track detectors have become one of the most important tools for many branches of science and technology. An attempt has been made to examine the suitability of the single-sheet particle identification technique in CR-39 and CN-85 polycarbonate by plotting track cone length vs. residual range for different heavy ions in these detectors. So, the maximum etchable ranges of heavy ions such as ⁹³Nb, ⁸⁶Kr and ⁴He in CR-39 and ⁴He and ¹³²Xe in CN-85 polycarbonate have been determined. The ranges of these ions in these detectors have also been computed theoretically using the Henke-Benton program. A reasonably good agreement has been observed between the experimentally and theoretically computed values.      

Nuclear track radiography of “Hot” aerosol particles

Nuclear track radiography was applied to identify aerosol “hot” particles which contain elements of nuclear fuel and fallout after Chernobyl NPP accident. For the determination of the content of transuranium elements in radioactive aerosols the measurement of the -activity of “hot” particles by SSNTD was used in this work, as well as radiography of fission fragments formed as a result of the reactions (n,f) and (γ,f) in the irradiation of aerosol filters by thermal neutrons and high energy gamma quanta. The technique allowed the sizes and alpha-activity of “hot” particles to be determined without extracting them from the filter, as well as the determination of the uranium content and its enrichment by ²³⁵U, ²³⁹Pu and ²⁴¹Pu isotopes. Sensitivity of determination of alpha activity by fission method is 5×10⁻⁶ Bq per particle. The software for the system of image analysis was created. It ensured the identification of track clusters on an optical image of the SSNTD surface obtained through a video camera and the determination of size and activity of “hot” particles.     

Radiography with Solid State Nuclear Track Detectors

The investigation of localisation is counted among the typical and important applications of nuclear track recorders. In this paper, after a comparison of the most important features of nuclear track recorders a system of their applications is given. On the grounds of information obtained from the tracks, eight groups of applications can be distinguished. One of them represents the four geometrical situations of the different types of radiography.

Taking radiography into account in the wider sense, as an investigation of localisation, then several cases of special localization tasks are known, which can be classified into two further groups of applications of track detectors. A survey of the applications of solid slate nuclear track detectors for all kinds of radiography is given on the basis of this definition of localisation experiments.     

The atomic force microscope as a fine tool for nuclear track studies

Atomic force microscopy (AFM) is a relatively new tool in the study of materials used in the nuclear track methodology. The sensitivity to detect ionizing nuclear particles is strongly influenced by the surface roughness of the material used as detector. In this contribution a surface analysis of several commercial polycarbonates used as nuclear track detectors is presented.     

FT-IR spectroscopy of carbon dioxide in CR-39 and SR-90 track detectors irradiated with ions and gamma-rays at different energies and fluences

Two types of polymeric track detectors CR-39 and SR-90 were irradiated with protons, alpha particles, heavy ions and gamma-rays at different energies and fluences. After irradiation these detectors were analyzed with an FT-IR spectrometer of Jasco type 5300 in transmission and ATR modes. We have found that CO₂ is produced not only by irradiation but also by polymerization. The amount of CO₂ in the detector material is closely related to the latent track formation.     

Annealing of heavy ion tracks in cellulose nitrate plastic track detectors

The effect of heat treatment on the latent tracks in cellulose nitrate plastic track detectors has been studied. The bulk etch rate increases with annealing temperature while the track diameters of different ions in cellulose nitrate decrease with increase in annealing time and temperature. Experimental results show that for heavier ions higher temperatures are needed for their complete erasure. The track length and track etch rate are decreased by the application of heat. Experiments reveal that annealing reduces track density. The vertical tracks are more stable than the oblique tracks and require higher temperature for their complete erasure.