CR-39 Solid State Nuclear Track Research Articles

Use of CR-39 solid state nuclear track detector in neutron personnel monitoring

Neutron sources like 241 Am –Be, 239 Pu –Be, 252 Cf and 14.6 MeV neutron generator are being used in oil exploration industries as well as in research institutions. While handling these neutron sources, personnel may be exposed to neutrons. Also personnel working in reactors, accelerators may receive dose from neutrons. These exposed individuals need to be monitored regularly for measurement of neutron doses. The individual neutron doses can be estimated by using Kodak NTA films and CR-39 Solid State Nuclear Track Detector with a polyethylene radiator to increase sensitivity in front in holder. Nearly 1450 personnel are being monitored regularly throughout the country on a quarterly basis. In India, the monitoring system adopted for individual neutron dose estimation having energy from 100 keV and above is described in this paper. Background counts of 0.20 mSv could be measured with CR-39 SSNTD foil system and it has been successfully introduced for Fast Neutron Personnel Monitoring for the country.

Watching at the correlation between the specific track-etch rate and the primary physical parameters of the swift ion interaction with the CR-39

Analysis of etched nuclear tracks in CR-39 solid state nuclear track detectors has recently been made possible by the confocal microscope. This recent innovation has opened up some particularly interesting perspectives. The main originality of this microscopy technique is that it makes it possible to work on numerical, three-dimensional images of chemically etched nuclear tracks in the CR-39. We have studied the performances of this new approach for light ions (H, He, Li and C) with kinetic energies typically of the order of the MeV per nucleus. First, we determined the response functions of the CR-39 for these ions. We were then able to show that aside from decreasing the analysis time of traditional methods, the confocal microscope greatly increases the sensibility of the detection. The aim of this study was to find a correlation between the response functions and the primary physical parameters of the interaction between the ion and the material, such as the linear energy transfer (LET), the restricted energy transfer (REL ω0 ), the integrated radial dose or the rate of ionization. Although these parameters presented a strong resemblance to the experimental response functions (they are all “Bragg” curves), none of them were correlated to the response function in an unambiguous way.

A Study on Ionizing Emissions from Limestone Samples using CR-39 Solid State Nuclear Track Detector

Limestone is an item most commonly consumed by the people in the Barak Valley area of Assam along with betel leaves. Also limestone chips are extensively used for water treatment in filter beds of these areas. A preliminary investigation on the activity of the samples of limestone, collected from the local market at Silchar, Assam, indicated the presence of beta and gamma-ray activity, prompting further investigations for the presence of alpha particle emitting radionuclides. Also the study of the ionising emissions from these samples using solid state nuclear track detector (SSNTD) has revealed the presence of spontaneous fission fragments along with alpha particles. This paper presents an account of the results obtained from the SSNTD studies of these limestone samples.

Determination of alpha-dose rates and chronostratigraphical study of travertine samples

Uranium and thorium contents in different layers of stratigraphical sedimentary deposits have been evaluated by using LR-115 type II and CR-39 solid state nuclear track detectors (SSNTD). A method has been developed for determining the alpha-dose rates of the sedimentary travertine samples. Using the U/Th dating method, we succeeded in age dating carbonated level sampled in the sedimentary deposits. Correlation between the stratigraphy, alpha-dose rates and age has been investigated.

The influence of the soil and plant natures and pollution on the radon and thoron alpha-activities inside various herbal infusions by using solid state nuclear track detectors

Uranium and thorium contents were determined in samples of various plants in the soils in which the plants were grown, and in herbal infusions made by boiling the plants in potable water, using CR-39 and LR-115 solid state nuclear track detectors. In addition, radon and thoron alpha-activities per unit volume inside the plants, soils and herbal infusions were measured. These measurements were completed by an investigation of the radon transfer between soils and plants and that between plants and herbal infusions, and also by the investigation of the influence of pollution due to different material dusts on the radon and thoron alpha activities inside the plants and their infusions.

Radon emanation in a limestone cave using CR-39 and LR-115 solid state nuclear track detectors

Radon alpha-activities were evaluated in different places of a quaternary cave, by using solid state nuclear track detectors (SSNTD). The maximum activity was detected in the place more moved back of the studied cave. The ventilation phenomenon has been investigated. The radon alpha activity and uranium content according to the growth of stalagmite and stalactite samples from the cave were evaluated. A positive correlation has been shown between the uranium distribution (radon) and the stratigraphic order of the stalagmite (and stalactite) samples.

Determination of Radon Equivalent Alpha-Doses in Different Human Organs from Water Ingestion Using SSNTD and Dosimetric Compartmental Models

Radon α-activities per unit volume have been measured in different drinking water samples belonging to different aquifers and sources by using CR-39 and LR-115 solid state nuclear track detectors (SSNTD). Radon initial equivalent α-dose rates due to water ingestion have been evaluated in the stomach assuming that all the radon ingested appears in this organ. The influence of the origin and quality of the water samples studied has been investigated. Committed equivalent doses have been determined in different human organs by using dosimetric compartment models. The influence of the radon mean residence time on the committed equivalent doses in the different compartments of the gastrointestinal system has been studied. The committed equivalent dose per unit activity of radon ingested has been evaluated in the stomach tissue and compared with literature data.

Stratigraphical Study of Quaternary Travertine Samples by Using CR-39 and LR-115 Solid State Nuclear Track Detectors

Radon α-activity, uranium content and activity ratios of uranium and thorium [A c (238U)/A c (232Th)] have been determined in different layers of stratigraphical quaternary travertine deposits in the Errachidia area (High-Atlas, Morocco), by using two solid state nuclear track detectors (SSNTD), of CR-39 and LR-115 type II. The mineralogy of samples has been determined by X-ray diffraction. Correlation between the stratigraphy, uranium content and radon α-activity has been investigated. An uranium-aragonite association has been found.

A new method for studying the transport of radon and thoron in various building materials using CR-39 and LR-115 solid state nuclear track detectors

Radon ( 222Rn) and thoron ( 220Rn) α-activities per unit volume were measured inside and outside different building materials by using two types of solid state nuclear track detectors (SSNTD) (CR-39 and LR-115 type II). In addition, the radon and thoron emanation coefficients of the studied materials were evaluated. Based on these data, the transport of radon and thoron across parallelepipedic blocks of the building materials could be investigated and radon and thoron global α-activities per unit volume outside different building material blocks were determined. Moreover, the diffusion length and the effective diffusion coefficient of radon in the building materials were evaluated and the total alpha activity due to radon in the atmospheres of different rooms consisting of different building materials was studied.

Atmospheric Neutrons, Dose Equivalent and Average Build-up-attenuation Coefficient in Buildings (Estimated by CR-39 Detector).

Long term (three years from Aug. 1994 up to Sep. 1997) irradiated prechemically etched CR-39 solid state nuclear track detectors were used for the estimation of recoil proton track densities and related dose equivalent of atmospheric neutrons whose energies (Enabove-0.5 MeV which we call the effective fast neutrons) cause observable recoil proton tracks. The CR-39 detectors were exposed to the ordinary atmosphere and to up and down sides of building ceilings to estimate the total effect of buildings, ceilings and air voids, on the effective fast neutrons fluences. Also the attenuation of such neutrons within concrete was investigated. It was found that atmospheric cosmic neutrons of fluences above -0.5 Me V decrease with the increasing of concrete thicknesses (0-12 cm) . The average build up factor B times the attenuation terme-Σt.d (build up-attenuation coefficient) B⋅e-Σt.dwas calculated for each ceiling and for concrete blocks. The results give agreements with experiments done hitherto.

Study of the influence of the lithological and hydrogeological parameters of aquifers on the radon emanation from underground waters using solid state nuclear track detectors

Radon-to-thoron ratios as well as radon and thoron activity concentrations in different underground water samples belonging to different aquifers in the Moroccan Middle Atlas area have been evaluated by LR-115 and CR-39 solid state nuclear track detectors (SSNTD) using a new calibration method. The radon isotope (222Rn) was used as a tracer for studying the water exchange between different aquifers of the area studied. The influence of the lithological and hydrogeological parameters of the aquifers on radon emanation were investigated.

Study of radon-222 concentration levels inside kindergartens in Amman

In this work, measurements of the indoor radon concentration levels were carried out for 74 kindergartens in Amman, Jordan. The number of children (four to six years old) attending these kindergartens are about 15,000. This study was performed during winter season by using time-integrated passive radon dosimeters, containing CR-39 solid state nuclear track detectors. We found that the radon concentrations inside the classrooms of these schools range from 40.7 to 193.5 Bq/m 3 with an average of 76.8 Bq/m 3. This average value is twice that of Amman's dwellings (mostly residential houses) found in previous studies (Abumurad et al., 1994 and 1996). An average radon level of 79.4 Bq/m 3 was found in the schools which are over 10 years old (65% of the schools), while an average level of 71.7 Bq/m 3 was found in those under 10 years old (35%). On the other hands, for the schools that have central heating systems (32.4%) the average radon level inside them was 78.6 Bq/m 3. For the schools that use kerosene portable heaters (51.4%), the average radon level was 72.9 Bq/m 3 and for those don not have any heating system (16.2%) their average was 86.5 Bq/m 3. Consequently, we believe that better ventilation rate is recommended.

Neutron flux distribution measurement methods & comparison

In this work attempts have been made to introduce a new application for CR-39 solid state nuclear track detector (SSNTD) to measure the thermal neutron flux distribution of the external neutron beam in a powder neutron diffractometer (PND) system using boric acid converter. Also a neutron radiography film with Gadolinium converter have been applied to measure the neutron flux distribution in order to compare and recheck the results obtained by the previous method.

A new method for evaluating the influence of building materials on radon emanation in marrakechi Dwellings

Radon emanation has been studied in different rooms of buildings in Marrakech by using LR-115 and CR-39 solid state nuclear track detectors (SSNTD). A new calibration method has been developed based on calculating the probability for an emitted α-particle to be registered on a SSNTD. The thoron-to-radon ratios as well as thoron and radon activity concentrations in the dwellings studied have been determined by exploiting the measured track densities, due to the α-particles emitted by radon, thoron and their daughters, registered on the SSNTD. The influences of building materials, pollution and painting layers and papers were also investigated.

Study of the granulation influence on uranium content in sedimentary phosphate samples by using CR-39 and LR-115 solid state nuclear track detectors

Different samples have been taken from different layers in a sedimentary phosphatic deposit and sieved. Different granulometric fractions have been selected. Uranium contents of each phosphate sample and its corresponding selected fractions were determined by using CR-39 and LR-115 solid state nuclear track detectors (SSNTD). Correlation between fraction grain diameter and uranium enrichment factor has been investigated. The different selected fractions of the studied phosphate samples were analysed optically. A relationship between uranium content and fraction's composition was found.

Characterization of a 292 MeV/n 19F beam after passage through a thick Plexiglas target

A number of parameters, important for planning cancer treatment with heavy ions, were determined by an experiment where irradiated tissue was simulated by Plexiglas (C 5H 8O 2). CR-39 solid state nuclear track detectors were used to measure the number of projectile fragments formed due to the interaction of a 292 MeV/n 19F beam with a 2.5 cm thick Plexiglas target. From these measurements the partial cross-sections of fluorine fragmentation leading to the production of oxygen, nitrogen, carbon and boron nuclei were found to be (131 ± 10) mb, (100 ± 9) mb, (113 ± 9) mb and (53 ± 6) mb, respectively. Also, the linear energy transfer distribution due to the primary beam and its measured fragments which traversed a given thickness of Plexiglas was obtained. By measuring track opening positions on both sides of two detector foils, the angular spread of the primary beam in the target was found to be (0.22 ± 0.02)°.

A new method for studying the influence of pollution and soil nature on the radon emanation from water samples by using solid state nuclear track detectors

Radon emanation from surface water and groundwater samples has been studied by using CR-39 and LR-115 solid state nuclear track detectors (SSNTD). A calibration method for determining the thoron and radon concentrations of the water samples studied has been developed. The effect of pollution due to coal fly ashes, cement and granite dusts on the radon emanation from water samples has been investigated. The influence of the radon source on the radon emanation rates from water samples has been studied.

Measurement of Radon Concentration in Private Houses in the Eastern Part of Al-Qaseem Province of Saudi Arabia

CR-39 solid state nuclear track detectors were used to measure radon concentration in a city in the eastern part of Al-Qaseem province in Saudi Arabia. The dosemeters were distributed over 58 houses. Results obtained show that the mean radon concentration in this area is 67 ± 8 Bq.m -3 which is higher than the level reported in former studies in other parts of the country, but is still within normal limits. It is also found that, in general, the level in lower floors is higher than that in upper ones in all houses. It is believed that the high radon level in this part of the country may be attributed to its geographic location.

Atmospheric radon levels and its emanation rate in the environment of Kaiga

A systematic study of atmospheric radon levels and of radon emanation rates was conducted in the environment of Kaiga on the south-west coast of India where the installation of nuclear power reactors is in progress. 222Rn emanation rates were estimated employing the accumulating chamber method and were found to vary from 5.6 to 62.9 mBq m −2 s −1 with a geometric mean of 30.0 mBq m −2 s −1. The atmospheric concentrations were estimated using CR-39 solid state nuclear track detectors (SSNTDs) and found to vary from 4.7 to 27.9 Bq m −3 with a geometric mean of 13.4 Bq m −3. The results show a strong correlation between emanation rate and atmospheric concentration while showing a poor correlation between 226Ra concentration in surface soil and atmospheric concentration of 222Rn. The results are also compared and discussed in the light of relevant literature reported for other environments.

A new simple method to study the induction time

In the present work, an easy automatic method based on foil laser scattering measurements is applied to evaluate the induction time ( t i) in CR-39 solid state nuclear track detectors for different etching temperatures. A quantity q, proportional to the amount of suface layer removed is plotted against etching temperature. The experimental results are compared with those obtained from microspectrophotometer measurements for Macrofol-E detectors.