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The ENEA fast neutron dosemeter is based on a planar PADC (Poly Allyl Diglicol Carbonate) placed in a polyethylene holder. The present paper reports the results of a preliminary experimental comparison of a CR-39 ® material with the addition of 0.1% of DOP (Dioctylphthalate), produced by the Italian company Intercast Europe S.p.A., and TASTRAK material produced by the British company TASL (UK). The etching procedure is for both materials: pre-etching with 40% KOH water solution 6.25 N and 60% ethyl alcohol at 70 °C followed by 12 h of etching in 6.25 N KOH water solution. Dosemeters have been irradiated with neutron sources ( 241 Am-Be) at the ENEA Calibration Service for Ionizing Radiations. For each kind of set of detectors, 10 have been irradiated free-in-air at 1 mSv of H*(10) with an 241 Am–Be source at ENEA Calibration Service for Ionizing Radiations, whilst the other 40 detectors have been used as background samples. The dosimetric performance of the material for fast neutrons is expressed in terms of sensitivity, background value and lowest detectable dose. For each batch the value of the average background signal, the average neutron sensitivity and minimum detectable dose equivalent have been determined. Two identical tests have been completed and separated with a time of 6 months in order to evaluate the aging effect on the material stored in the same conditions. The results are compared with our acceptance test. A comparison of criteria the performance of the two CR-39 ® materials is reported.

This paper briefly reviews proton radiobiology. Clinical applications of protons produced by accelerators have led to a significant biological literature that contributes to our goal of estimating the proton shielding requirements for human interplanetary missions. Protons are primarily a low-LET radiation with biological effects much like gamma radiation. There are however data indicating enhanced biological effectiveness for small doses of very low energy (10 MeV) stopping protons, and some limited data for extremely high energy protons (0.5 GeV).

For the last few years, the Besancon and Dresden teams have been working in a parallel way on light ion (protons and alphas) registration characteristics for the CR-39 SSNTD. Even if the two groups use different approaches, the main part of both investigations concerns the study of the track etch rate (VT) and the consequences of the obtained results, which have provided us with greater understanding of detection limits. After recalling the methods used to determine the VT from both teams, will show how fundamental datal related to the registration properties of the CR-39 detector can be extracted. Indeed, the knowledge of an analytical relation for the VT enables the relationship between this velocity and the primary deposited energy to the examined with respect to the same spatial variable (the instantaneous depth of penetration (x) of the incoming particle). According to experimental uncertainties, the Bragg peak of the primary ionization coincides within a very close range with the maximum of the VT. Moreover, if increasing the etching parameters (C, T) increases the maximum VT value, these changes do not affect its position with respect to the instantaneous depth of penetration. Taking into account the reduced etch rate, the Dresden team found that both protons and alphas exhibit the same behavior when this rate is plotted versus the primary energy deposition rate. As a consequence, the corresponding reduced etch rate is always identical no matter what type of particle deposits a given amount of energy (e.g. proton or alpha). The Besancon team has corroborated the results obtained by the Dresden group for alphas and have extended the study to various etching conditions. From these results, the sensitivity of the CR-39 SSNTD is obtained in terms of critical LET and leads to a very low energy threshold for alpha particles. We will see throughout this paper that the lower threshold does not seem to depend on the etching parameters.

This paper shows the limitation of general order peak fitting and peak shape methods for determining the activation energy of the thermoluminescence glow peaks in the cases in which retrapping probability is much higher than the recombination probability and the traps are filled up to near saturation level. Right values can be obtained when the trap occupancy is reduced by using small doses or by post-irradiation partial bleaching. This limitation in the application of these methods has not been indicated earlier. In view of the unknown nature of kinetics in the experimental samples, it is recommended that these methods of activation energy determination should be applied only at doses well below the saturation dose.

In this paper we present the observation that Sr 2 B 5 O 9 Br:Eu 2+ shows thermoluminescence after illumination with UV photons, even when the photon energy is insufficient to induce band to band transitions. The role of the Eu 2+ ions to the trapping process and possible models to explain the observation will be discussed.

Anion-deficient aluminum oxide doped with carbon (Al 2 O 3 :C) is not only an extremely sensitive thermoluminescence (TL) material, but is well suited to optically stimulated luminescence OSL applications due to a high cross-section for interaction of light with radiation-induced trapped charge. Several different OSL readout protocols have been suggested, including pulsed OSL (POSL), and “delayed” OSL (DOSL). This paper examines the properties of Al 2 O 3 :C for application using these two readout protocols. The POSL technique utilizes the prompt luminescence that results from the direct recombination of released charge carriers at luminescence sites ( F -centers in Al 2 O 3 :C). Following a pulse of stimulation light using a laser, the POSL signal is observed to decay with a temperature-independent lifetime of ∼35–36 ms. The DOSL signal, on the other hand, utilizes the temperature-dependent signal resulting from the capture of released charge carriers by shallow traps. The decay of the luminescence component after the stimulating pulse has a lifetime of several hundred ms, depending upon temperature. The dependence of the DOSL signal on readout temperature can be explained in terms of the involvement of the shallow traps in the process. However, the intensity (not the lifetime) of the POSL signal is also slightly temperature dependent. It is conjectured that this may be caused by a thermally assisted optical detrapping process involving localized excited states. Different forms of Al 2 O 3 :C are examined. By modifying both the concentration and energy distribution of the shallow traps material optimized for DOSL applications can be engineered. In contrast, the best material for POSL is grown with no shallow traps. The integrated light output in a typical POSL measurement is approximately a factor of 7–8 greater than that of DOSL, even for a DOSL-quality sample.

Isothermal post-irradiation annealing at room temperature, i.e. practical fading of alpha particle tracks in cellulose nitrate (CN) detectors has been studied. It is found that the fading process, by itself, lasts about a month. Thereafter the registration efficiency is stabilized and holds constant for about ten days. Then a new process begins which was not observed earlier for CN-detectors. This new process-growing has time boundaries too and lasts 1–2 months. On its completion the registration efficiency becomes equal to the initial value. Experimental data obtained in 1990–1993 on fading and growing of alpha particle tracks are presented in this paper for a long-term storage of irradiated detectors. Mathematical description of the dependence obtained is given for two processes—fading and growing, and some facts elucidating the nature of this effect are considered.

In electron spin resonance (ESR) dating the response of the sample to irradiation has been traditionally determined from the increase in the height of a selected peak in the differential of the absorbed power spectrum. In this, it differs from luminescence dating, where the equivalent of the height of the absorbed power spectrum or its integral is used. Conceptually, peak height is a mathematically derived surrogate variable for the number of radiation induced defects, which are given by the area under the curve in the absorbed power spectrum. This paper examines whether the same environmental dose (De) can be obtained by using peak heights, the absorbed power or the integral of absorbed power in the additive dose technique. Except in special cases, De will be different for the different methods. Moreover, the reason for the differences is the different degree of interference between wide and narrow peaks in the different methods. Therefore, using the area under the absorbed power curve or other integral techniques is NOT ipso facto the best method for any given spectrum and, moreover, a more accurate estimate of De will generally be obtained using the traditional (in ESR) differential peak heights method or a modified form of it. Differential techniques might be very profitably used in luminescence dating: the differential spectrum not only shows detail which may be obscured in the integral curve, but also provides a very simple means of mathematically isolating a valid dating defect and minimising interference by undesirable defects, possibly extending the range of samples which may be reliably dated.

This paper presents results obtained from an organic polymer polyallyl diglycol carbonate (PADC) irradiated with protons of different energies. Samples, made of PADC foils 600 μm thick, were irradiated at normal incidence with monoenergetic protons from a linear accelerator. Latent tracks induced by protons in the surface layer of the samples were etched using a chemical (CE) and an electrochemical (ECE) etching, respectively. The etching time was varied. Diameters of CE and ECE tracks were measured under specific magnifying and viewing conditions, and frequency distributions were determined by means of an image analysis system.

A fast neutron personal dosemeter based on the two-step electrochemcially etched CR-39 detectors has been developed by the “Centre de Radioprotection et de Surete” (CRS), in as simple a form as possible to be used in routine monitoring of neutron irradiated workers in Algeria. This paper presents the dosimetric characteristics of the developed dosemeter such as energy and angle dependence, dose equivalent response and low limit of detection which are much improved compared to our previous work. The obtained energy response is both flatter (±25%) and extended to lower energy (≈25 keV). Also, a lower detection limit of about 90 μSv has been achieved. In addition, the evaluation of the energy response in term of track size distributions has been performed.

In space, radiation effects in which a large amount of energy is transferred by a single particle are observed. These effects can be caused by either the direct ionization of a cosmic ray heavy ion or alternatively by the ionization of short range target fragments which are produced inside the material by interactions of cosmic ray particles. Protons of the lower radiation belt contribute significantly to target fragmentation; especially in the South Atlantic Anomaly (SAA). To allow predictions of possible radiation hazards the characteristics of these interactions at energies below 100 MeV must be understood in detail. We have performed an experiment to measure the proton induced fragmentation cross sections for carbon target nuclei at about 70 MeV/nucleon and to determine some characteristics of the kinematics of the target fragments. For this purpose experimental setups with CR-39 track detectors were used. In this paper we describe the experimental technique and present some preliminary results.

Measurements of the diffusion constant and the permeability of ion irradiated Makrofol KG (polycarbonate) sheets have been done with Argon and Nitrogen as diffusion gas. The polymers were irradiated at the “Gesellschaft fur Schwerionenforschung” (GSI, Germany) with Uranium and Gold ions with energies of about 10 MeV/nuc. The fluence varies from 3·10 9 to 4·10 11 ions/cm 2 . For the irradiation the material was put together in stacks with layers of 8 μm thickness. This allows to relate a definite amount of energy loss to each layer and to examine the dependence of the diffusion constant and the permeability on it. For comparison electron irradiated and pristine material (i.e. the untreated material) were also measured. The general tendency shows an increase of the diffusion constant and the permeability with growing energy loss up to a certain limit. In case of the highest energy loss the material changes its appearance and the diffusion constant and the permeability values are remarkable lower than those of the pristine material. A first trail of explanation might give the three-zone-model presented in this paper.

To understand recent developments in geochronology, a thorough knowledge of etching mechanisms is necessary. An earlier study, which we presented at the 17 th International Conference on Nuclear Tracks in Solids, was aimed at demonstrating how the segmentation of latent fission tracks in apatite governs etching track profiles. This study also highlighted the influence of crystallography and reagent diffusion on the morphology of etched tracks. The goal of this paper is to simulate track etching phenomena (first of all in non-segmented tracks) taking crystallographic and diffusional aspects into account. To this end, we have developed a software program which allows for a three-dimensional representation of the etching figures simulated. During simulation, we accounted for the influence of crystallography on the etching process by allowing for an etching rate dependant on the parameters of the crystal lattice. Thus, in the case of apatite with a symmetry of P 6 3/m , we applied the concept of hexagonal etching prisms. For the diffusion model of the etchant in the tracks, however, we applied Fick's laws by associating the etching-rate vectors with two geometric parameters that vary with time. We subjected Durango apatites to irradiation by swift heavy ions in the GANIL accelerator. This was done perpendicularly to the prismatic or basal planes. They were then etched by acids of varying concentration. The morphological parameters of the etched tracks were observed using electron microscopy on the different irradiated planes. By measuring the diameters and aperture angles, we were able to adjust the simulation parameters.

The paper describes an examination of the dosimetric properties of natural quartz grains extracted from ancient fired materials. Eleven samples of different origin were tested for their TL and GLSL (green light stimulated luminescence) sensitivities within the mGy dose range. Very promising results were obtained showing the possibility of measuring the doses of around 10 mGy with 1% precision using GLSL or TL and using the single aliqout technique for natural quartz as a dosimeter. The lowest detectable dose was estimated to be lower than 500 μGy. The results obtained indicate that natural quartz grains from selected materials could be used for the dosimetry of environmental gamma radiation for the purposes of paleodosimetric dating methods as well as for accident dosimetry.

We have continued our studies of heavy ion projectile fragmentation using nuclear track detectors. Based on automatic track measurement it was possible to perform experiments with high statistical significance. Beams of different ions from the Berkeley BEVALAC, the Dubna Synchrophasotron, the Brookhaven AGS and the GSI Darmstadt SIS have been used. With CR-39 and BP-1 glass detectors we have studied the process of electromagnetic dissociation, we investigated multifragmentation and continued the search for quark nuclear complexes. This paper gives an overview of these experiments. Details of the experimental technique are discussed.

This paper describes a methodology to characterize the response of a detector to alpha particles of different incidences and energies using an experimental irradiation system and an etching model. Implications for radon dosimetry are discussed. For each incident energy there is a particular angle above which alpha particles no longer induce an observable etched track. This angle also depends on the etching and on the conditions of observation of the detector. It is necessary to known the variation of that critical angle with incident alpha particle energy for given etching and observation conditions in order to determine the theoritical detection efficiency of a radon detector. This variation was studied for a CR39 detector (Tastrack, G.B.) over the energy range of the alpha particles emitted by radon (5,5 MeV) and its two short-life daughters : Po218 (6 MeV) and Po214 (7,7 MeV).

The present paper reports studies on the applicability of fluorescent lamp phosphors in accidental radiation dosimetry. Strontium orthophosphate, which is used as one of the components in the fluorescent lamps, has been studied for its thermo-luminescence (TL) characteristics on exposure to different doses of beta irradiation. The analysis of the TL glow curve of the phosphor, with a well-defined glow peak at 553 K , and other experiments carried out have proved the utility of strontium orthophosphate as dosimetric material in the range of 10– 200 Gy . It has been observed that the material satisfies most of the fundamental criteria for a good TLD-material. A fluorescent lamp developed with this material as TLD grade lamp phosphor is thus expected to serve twin purposes of providing illumination and monitoring the radiation released during a nuclear accident.

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 4 He -ions, and with 5.5 MeV α 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.

In this paper, we study the thermal annealing of proton tracks of 4 and 6 MeV at temperatures ranging from 150 to 240°C in CR-39 polymer detectors. A special experimental set-up for irradiating the detectors was arranged to obtain adequate proton beams from the Cyclotron CV-28 at IPEN/SP, Brazil. We report experimental data on track densities, track diameters, and activation energies based on current annealing models for the annealing of proton tracks in the energy range investigated. A value of (0.20±0.02)eV was determined as the mean activation energy of the annealing process in CR-39 detectors.

This paper deals with the examination of thermoluminescence (TL) optical spectra (200–800 nm) for deep traps (DT) observed near 730 K (DT1) and 785 K (DT2) at β =2 K/s in dosimetric α -Al 2 O 3 crystals. The DT1 spectrum consisted of two luminescence bands near 3.56 and 2.42 eV. The DT2 spectrum had one band near 2.95 eV. The 3.56 eV emission band was assigned to the F + -center luminescence and the 2.95 eV band to the F-center luminescence. The excitation spectra of the 2.42 eV emission band measured at RT had one peak at 4.11 eV. The intensity correlated with filling of deep traps. It was supposed that anion-defective corundum contained complex F-type centers. The state of those centers changed upon exposure to UV irradiation at a high temperature.

This paper presents advances in a procedure for alpha particle analysis using the nuclear tracks formed in solid-state materials. This method is based on the relationship between the energy deposited in the material by ionizing particles and the track developed after a well-established chemical process. The experimental study included alpha particles in the energy range from 3.2 to 5.8 MeV emitted by 148Gd, 238U, 239Pu and 244Cm. The quantitative results provide a clear signature to identify each one of the radioisotopes based on the formed track parameters. The track analysis is performed with a digital image analysis system associated with a PC mathematical processor. The wide range energy response makes this method a promising analysis system.

Track etched membranes (TEMs) obtained by irradiation of polymer films with heavy ions and subsequent etching of latent tracks can be applied in many fields and among others in biomedicine as well. It is important to know radiation resistance of TEMs because of wide use of radiation sterilization in the case of biomedical devices. Tensile properties of TEMs made of PET and PC films with the thickness of 10 μm after electron irradiation at different doses are known from literature. Nowadays TEMs are being manufactured from thicker (20 μm) PET and PC films as well as polyethylene naphthalate (PEN) films are proposed for TEMs. It seems to be important to get data about radiation resistance of new kinds of TEMs. Samples of polymer films made of PET and PEN with the thickness of 19–25 μm and TEMs made of such materials have been irradiated using 10 MeV electron beam with doses up to 990 kGy. Tensile properties and SEM photographs of the samples after irradiation are given in the paper.

This paper reports the experimental results of studying the thermoluminescence (TL) of ZrO2 doped with Eu exposed to light of wavelength in the range of 200–900 nm. The photoluminescence spectrum induced by 275 nm UV light exhibited three maxima at 588, 612 and 650 nm with the major emission at 612 nm. Among 210, 260 and 320 nm UV light for the same exposures, the 260 nm UV radiation induced the highest TL response. Its glow curve exhibited two peaks at 120 and 290°C for all the wavelengths studied. The 120°C peak faded completely within the first 24 h after exposure. Meanwhile, the 290°C peak shows great stability for a long time. The TL response of Eu-doped ZrO2 exposed to 260 nm as well as to 320 nm UV light was linear for a wide range of exposure times. The results showed that ZrO2:Eu films deposited on glass substrates have the potential to be used as UV dosimeters in personal or environmental dosimetry.

In the present paper we have investigated sensitization of the 220°C TL peak in quartz, separated from sand, as a function of pre-gamma dose and post-irradiation annealing treatment at a test gamma dose of 50 Gy. A pre-gamma dose of 2.50 kGy followed by 400°C post-irradiation annealing treatment yielded the maximum sensitization factor of 35. The sensitization decreases for pre-doses higher than 2.50 kGy as well as for post-irradiation annealing temperatures higher than 400°C. The sensitization of the peak in quartz due to accrued geological dose of 72 Gy and thermal annealing treatment was estimated to be 2.36. The position and shape of the TL glow curve in sensitized and unsensitized samples was nearly the same.

This paper examines the effect of high-dose irradiation on the optically stimulated luminescence (OSL) of Al2O3:C, principally on the shape of the OSL decay curve and on the OSL sensitivity. The effect of the degree of deep trap filling on the OSL was also studied by monitoring the sensitivity changes after doses of beta irradiation and after step-annealing of samples previously irradiated with high doses. The OSL response to dose shows a linear-supralinear-saturation behavior, with a decrease in the response for doses higher than those required for saturation. This behavior correlates with the sensitivity changes observed in the samples annealed only to 773 K, which show sensitization for doses up to 20-50 Gy and desensitization for higher doses. Data from the step-annealing study leads to the suggestion that the sensitization is caused by the filling of deep electron traps, which become thermally unstable at 1100-1200 K, whereas the desensitization is caused by the filling of deep hole traps, which become thermally unstable at 800-875 K, along with a concomitant decrease in the concentration of recombination centers (F+ -centers). Changes in the shape of the OSL decay curves are also observed at high doses, the decay becoming faster as the dose increases. These changes in the OSL decay curves are discussed in terms of multiple overlapping components, each characterized by different photoionization cross-sections. However, using numerical solutions of the rate equations for a simple model consisting of a main trap and a recombination center, it is shown that the kinetics of OSL process may also be partially responsible for the changes in the OSL curves at high doses in Al2O3:C. Finally, the implication of these results for the dosimetry of heavy charged particles is discussed. c2004 Elsevier Ltd. All rights reserved.

Anion-defective α-Al2O3:C single crystals, commercially grown in Russia as TLD-500K detectors, have been increasingly used for environmental radiation measurements. These detectors have attracted great interest because of their high sensitivity and simple annealing procedure. The application of TLD for routine measurements in environmental monitoring, involving storage periods which may extend up to one year, imposes strict requirements on the fading, the change in sensitivity with long periods of time and other characteristics of the dosimeters. Many of these properties of TLD-500K have not yet been completely investigated and need to be further explored. This paper presents some results of long-term testing of the detectors. The variation in sensitivity within the detector group as well as changes of the sensitivity with time and number of read-outs were estimated. All tests were made by using low doses of irradiation, adequate for environmental dosimetry.

This paper reports on the radioluminescence characteristics of LiF:Mg,Ti induced by 4 MeV linear accelerator electrons. The main emission peak of the luminescence is found at 410 nm, but weaker emission occurs around 320, 360, 460, 520 and 560 nm as well. The relative intensities of the emission bands show a strong dependence on the Mg concentration of the sample. The radioluminescence signal reaches its maximum typically 1.5 ms after the irradiation pulse, and decays with a half-life of 4–6 ms. Both the build-up time and the half-life decreases with increasing Mg concentration. The luminescence yield shows a strong dependence on the irradiation dose.

This paper reports the first attempt to use L-band spectroscopy for estimating the sensitivity of whole teeth to fast neutrons and gamma-rays. Three teeth were successively irradiated first with fast neutrons with a wide energy spectrum (mean energy around 30 MeV) up to approximately 160 Gy and then with gamma-rays up to approximately 14 Gy. After each irradiation, L-band (approximately 1 GHz) EPR spectra of each whole tooth surrounded by the surface-coil resonator were recorded, yielding a single composite line principally due to CO2- and native radicals. The sensitivities are estimated by the slopes of the linear dose response curves of the dosimetric CO2- radicals. The ratios of the gamma/neutron sensitivities were found to be in the range 8-9 (+/- 2) for the three teeth.

In the present paper the experimental and calculated data of SEU rate in microcircuits operating onboard spacecraft are compared. The main features of models and the calculation methods, which are incorporated in the SEREIS software package, are considered. The main features of models, and the calculation methods are considered. The contribution of the different space radiation components (ERB Protons; GCR particles and SEPs) to the SEU rate is discussed with an allowance for the shielding thickness.

The radiation environment on LDEF was monitored by cumulative absorbed dose measurements made with TLDs at different locations and shielding depths. The TLDs were included in four experiments: A0015(a) Biostack, P0004 Seeds in Space and P0006 Linear Energy Transfer Spectrum Measurements at the trailing edge (west side) of the satellite; M0004 Fiber Optics Data Link at the leading edge (east side); and A0015(b) Biostack at the Earth side. The shielding depths varied between 0.48 and 15.4 g/cm2, Al equivalent. Both the directional dependence of trapped protons incident on the satellite and the shielding thickness were reflected in absorbed dose values. The trapped proton anisotropy was measured by TLDs at the east and west sides of LDEF. At the east side doses ranged from 2.10 to 2.58 Gy under shielding of 2.90 to 1.37 g/cm2 (M0004) while on the west side doses ranged from 2.66 to 6.48 Gy under shielding of 15.4 to 0.48 g/cm2 (P0006). The west side doses were more than a factor of two higher, where the vertical shielding thicknesses to space were equal. Other west side doses of 3.04 to 4.49 Gy under shielding of 11.7 to 3.85 g/cm2 (A0015(a)) and 2.91 to 6.64 Gy under shielding of 11.1 to 0.48 g/cm2 (P0004) generally agreed with the P0006 results. The Earth side doses of 2.41 to 3.93 Gy under shielding of 10.0 to 1.66 g cm2 (A0015(b)) were intermediate between the east side and west side doses. Calculations utilizing a model of trapped proton spectra were performed by Watts et al. (1993) and comparisons of dose measurement and calculations may be found in a companion paper (Armstrong et al., 1996).

In this paper the absorption spectra, photo- and X-ray luminescence, and scintillation characteristics of monocrystalline YTaO4 have been studied. The intensive band with maximum at 350 nm in X-ray luminescence spectra at room temperature has been observed. The scintillation effiency of YTaO4 monocrystal is about 20%.

A novel track density measurement method is introduced based on thermal neutron activation of some dye elements like Bromine and Sodium in quickly dyed electrochemically etched tracks (Quick-DYECETs) in polycarbonate (PC) detectors. The 82 Br and 24 Na gamma activities measured are then related to the DYECET density and thus to the particle fluence or dose. The method seems having a good potential for large-scale automatic ECE track counting. Some results are presented and discussed in this paper.