CR-39 Solid-state Nuclear Track Detectors Research Articles

Assessment of photon and proton-induced activation in particles accelerators.

Nuclear activation affects all operating, future, or dismantled particle accelerators used in various fields, from medical applications to industrial applications. This work is concerned with the study of the radioactivity induced in various materials (Sc, Cu, Tb, Ta, W, Au) irradiated by hard Bremsstrahlung photons from an electron beam and by secondary neutrons induced by a proton beam. In both cases, the primary beam features an 18 MeV kinetic energy. We have performed Monte Carlo simulations with MCNP, GEANT4, FLUKA, and PHITS, coupled with the analytical codes CINDER'90 or FISPACT-II, to estimate the threshold reaction rates and the induced radioactivity in the samples. We compared the simulations with experimental activation measurements performed by high-resolution gamma spectrometry at a decommissioned medical LINAC and around the CYRCé cyclotron. We also used CR-39 solid-state nuclear track detectors to characterize the thermal and fast neutron components of the secondary fields.

Radionuclides distribution in soils and radon level assessment in dwellings of Mungo and Nkam Divisions, Cameroon.

Radionuclide and radon levels have been investigated in soil samples and residential environments within the Mungo and Nkam Divisions of the Littoral Region. These analyses employed gamma spectrometry facilitated by a NaI (Tl) detector for soil samples, yielding average activity concentrations of 226Ra, 232Th, and 40K at 23.8, 72, and 105Bqkg-1, respectively. Various radiological parameters were calculated to evaluate radiological hazards. Additionally, the indoor radon concentrations were quantified utilizing the CR-39 solid-state nuclear track detector (Radtrack), revealing an average concentration of 25Bqm-3 and an associated inhalation dose of 0.66mSv y-1. Risk assessments for lung cancer attributable to indoor radon exposure incorporated models such as the Harley model. An observed moderate correlation between indoor radon levels and external 226Ra concentrations implies that radon intrusion indoors might be substantially influenced by the 226Ra present in the subjacent soil, considering the construction of residential structures directly upon these terrains.

Indoor Radon Measurement in Buildings of A.O.R.N Cardarelli, the Largest Hospital of National Relevance in Southern Italy

: Indoor radon concentrations constitute a major source of exposure to ionizing radiation for humans. It has been estimated that radon contributes about 10% of deaths from lung cancer in the USA and Europe. In Italy, current legislation establishes that the concentration of radon must be monitored in all workplaces located in a basement and on the ground floor. In this study, the indoor radon concentration of 20 multi-floor buildings on the Cardarelli Hospital was measured during two consecutive semesters. The survey was carried out with CR-39 solid-state nuclear track detectors (SSNTDs). Radon concentrations were found to range from 4 Bq/m3 to 424 Bq/m3, with a median of 24 Bq/m3. The dependence of the radon concentrations on the measurement floor and the room-to-room spatial variation was also analyzed.

The Etching Effect Methods in Registration Properties on CR-39 Nuclear Track Detector

In this work, we use three different etching techniques—water bath, microwaves, and hotplate stirrer devices—in an effort to confirm the optimal etching time and conditions for tracks in the CR-39 solid-state nuclear track detector following irradiation to an alpha particle source (241Am). The research shows that the water bath’s maximum track density is 57596 tracks/cm2, appearing at 90 and 150 minutes. On the other hand, the hotplate stirrer’s maximum track density is 28050 tracks/cm2, appearing at 90 and 150 minutes. The microwave is the best etching method since it generated the tracks (65076 tracks/cm2) in a relatively short amount of time (10 min). The computation of the etching parameters, which are the bulk etch rates (VB), track etch rate (VT) and track etch ratio (V), was investigate in the etching properties. The time for the appearance of all traces of the microwave device is at a time of 10 minutes, followed by a hotplate stirrer at a time of 90 minutes, then a water bath at a time of 120 minutes.

Determination of radon activity among beach soil samples in Jeddah and Al-Qunfudhah, Saudi Arabia

Natural radioactive materials have a negative impact on public health, especially on people exposed to the sun on beaches. Due to the high temperature in Makkah Al-Mukarramah region, many people resort to going to the sea, and regarding the risks that the public is exposed to, we focus our research on studying and drawing a radiation map of the Red Sea beaches. Also, identify the risks that the public is exposed to while on the various beaches. The study was carried out using a CR-39 solid-state nuclear track detector. The results showed that the average concentration of radon gas on the beaches of Jeddah was 481.34 ± 40.63 Bq / cm3, while the average concentration of radon gas in the city of Al-Qunfudhah was 282.36 ± 38.40 Bq / cm3. 10% of the radon gas concentration values were higher than the safe limit. The mean values for radium for all measured samples were 4.41 ± 0.61 Bq/kg, while the mean values for uranium were 0.22 ± 0.03 ppm. All radium and uranium values were within the internationally permitted limits. The results of the measured beaches indicate that the Red Sea beaches in the Makkah Al-Mukarramah region are safe for use and do not have high life-threatening rates, except for Al-Hamra Corniche Beach in Jeddah, which was higher than permissible. It is recommended to monitor the beach and remove any waste so that its percentage on the beach does not increase. It is also recommended to complete the study on the rest of the Red Sea beaches.

A study of 226Ra concentration and radon exhalation rates in different geopolymer cement samples using CR-39 solid state nuclear track detector

Radon is a naturally occurring radioactive gas that is known to cause lung cancer. Therefore, it is essential to measure and determine the concentration of radon in different materials. The purpose of this research is to measure and analyze the levels of radon concentration, radium concentration, and radon exhalation rates in various geopolymer cement mixes. These mixes are made from slag or metakaolin blended with different ratios of fly ash, silica fume, and cement kiln dust. The main goal is to determine the potential risks associated with using geopolymer cement materials in construction and how they may impact indoor air quality. To achieve this, the study will monitor the amounts of radon released from different geopolymer cement mixes and compare them to traditional cement samples. A CR-39 solid-state nuclear track detector will be used for monitoring purposes. Results of this study have revealed that the radon concentration varies from 4.03 to 348.21 Bqm−3 with an average value 62.01 Bqm−3. Radium concentration also changes from 15.18 to 926.47 Bqkg−1 with an average value 174.23 Bqkg−1. The value of the dissolved radon concentration in the collected samples alters from 4.57 to 394.87 Bqm−3 with an average value 70.32 Bqm−3. The mass exhalation rates are found to vary from 0.04 to 2.28 Bqkg−1h−1 with an average value 0.43 Bqkg−1h−1, while the surface exhalation rates vary from 0.91 to 78.92 Bqm−2h−1 with an average value 14.06 Bqm−2h−1. The Annual Effective Dose (AED), due to conducting the experiment indoors, has varied from 0.102 to 8.785 mSvy−1 with an average value 1.564 mSvy−1, where AED in the outdoor experiment has varied from 0.038 to 3.294 mSvy−1 with an average value 0.587 mSvy−1. According to the results, the geopolymer mixes labeled as (S) and (SS) containing 100% GGBFS and 85% GGBFS with 15% SF respectively has had the highest levels of radium concentration, radon concentration, dissolved radon concentration, radon exhalation rates, and AED. The investigation results indicate that, with the exception of samples (S) and (SS), the analyzed samples fall within the suggested range of acceptable values. Based on our results, it seems that all geopolymer samples except for (S) and (SS) are safe for being used in building materials production. We recommend utilizing these samples (S, SS) for public highways, bridges, and other buildings that have good ventilation.

Differentiating multi-MeV, multi-ion spectra with CR-39 solid-state nuclear track detectors

The development of high intensity petawatt lasers has created new possibilities for ion acceleration and nuclear fusion using solid targets. In such laser-matter interaction, multiple ion species are accelerated with broad spectra up to hundreds of MeV. To measure ion yields and for species identification, CR-39 solid-state nuclear track detectors are frequently used. However, these detectors are limited in their applicability for multi-ion spectra differentiation as standard image recognition algorithms can lead to a misinterpretation of data, there is no unique relation between track diameter and particle energy, and there are overlapping pit diameter relationships for multiple particle species. In this report, we address these issues by first developing an algorithm to overcome user bias during image processing. Second, we use calibration of the detector response for protons, carbon and helium ions (alpha particles) from 0.1 to above 10 MeV and measurements of statistical energy loss fluctuations in a forward-fitting procedure utilizing multiple, differently filtered CR-39, altogether enabling high-sensitivity, multi-species particle spectroscopy. To validate this capability, we show that inferred CR-39 spectra match Thomson parabola ion spectrometer data from the same experiment. Filtered CR-39 spectrometers were used to detect, within a background of ~ 2 × 1011 sr−1 J−1 protons and carbons, (1.3 ± 0.7) × 108 sr−1 J−1 alpha particles from laser-driven proton-boron fusion reactions.

The effect of geometrical parameters on the radon emanation coefficient and different radon parameters

Radon is a radioactive gas produced from the uranium-238 series. Radon gas affects public health and is the second cause of lung cancer. The study samples were collected from one area of the city of Jazan, southwest of the Kingdom of Saudi Arabia. The influence of engineering and physical parameters on the emanation coefficient of gas and other gas parameters was studied. Parameters for radon were measured using a CR-39 Solid-State Nuclear Track Detector (SSNTD) through a sealed emission container. The results showed that the emanation coefficient was affected directly by the change in the grain size of the soil. All parameters of measured radon gas have the same behavior as the emanation coefficient. The relationship between particle size and emanation coefficient showed a good correlation. The values of the emanation coefficient were inversely affected by the mass of the sample, and the rest of the parameters showed an inverse behavior. The results showed that increasing the volume of the container increases the accumulation of radon sons on the wall of the container, which increases the emission factor. The rest of the parameters of radon gas showed an inverse behavior with increasing container size. The results concluded that changing the engineering and physical parameters has a significant impact on both the emanation coefficient and all radon parameters. The emanation coefficient affects the values of the radiation dose of an alpha particle.

Estimation of Uranium Concentration in Urine Samples of Three Age Groups of Healthy Individuals in Najaf Governorate Using CR-39 and LR-115 Solid State Detectors

Uranium concentration was estimated in urine samples of three age groups, G1≤ 30 years, n=28, G2 age range of 31-40 years, n=28, and G3 of age > 40 years, n=32, using two types of detectors CR-39 and LR-115 solid-state nuclear track detector (SSNTD) for results comparison. Results showed that uranium mean level values for CR-39 were 1.961 ±0.08 µg/L, 1.810 ±0.09 µg/L and 1.814 ±0.076 µg/L for G1, G2 and G3 respectively, while the mean values of uranium concentration using LR-115 were 0.972 ±0.07 µg/L, 0.922 ±0.07 µg/L and 1.018 ±0.08 µg/L in G1, G2 and G3 respectively, with significant statistical difference between the results of CR-39 and LR-115 for each age group. Mean level values for females was 2.023± 0.09 µg/L and 1.813± 0.05 µg/L for males using CR-39 and it was 1.105± 0.09 µg/L for females and 0.933± 0.04 µg/L for males using LR-115, with significant statistical difference between results for each gender. It was concluded that G1 ≤ 30 years have the highest uranium pollution, noting that females were more polluted with uranium than males.

Environmental health risks of radon exposure inside selected building factories in Erbil city, Iraq

ABSTRACT The main objective of this research is to determine the environmental health concerns associated with radon gas accumulation and compare quantities in various kinds of construction factories in Erbil city. For this purpose, 52 dosimeters were deployed throughout 13 industries by using CR-39 solid-state nuclear track detectors (SSNTD). These tests were conducted out in factories over a 60-day exposure period. The results show that the radon concentration values ranged from (21 to 190) Bq . m − 3 , with an average of (86.36 ± 9) Bq . m − 3 , different from the studied samples, red brick samples show radon concentration over the Environmental Protection Agency’s recommended value of 148 Bq . m − 3 . The mean value of the annual effective dose was found to be (2.179 ± 1) mSv . y − 1 below and within the range of the reference level of (3–10) mSv . y − 1 of ICRP. The average annual lung cancer rate per 106 people was shown to be (94.125). The dose rate to lungs (DLungs) varied from (1.07 to 7.11) nGy . h − 1 , with an average value of (3.454) nGy . h − 1 . The annual effective dose equivalent for lung AED E lung to tracheobronchial AED E T − B and pulmonary/ pulmonary lymph region AED E P + PL , varies from (1.62 to 10.76), with an average value of (5.23) mSv . y − 1 and from (0.81 to 5.38) mSv . y − 1 , with an average value of (2.615) mSv . y − 1 , respectively. The present results revealed the need for radon monitoring measurements because worker exposure in some factories can exceed permitted levels. Finally, owners should improve the factories ventilation systems to avoid the accumulation of 222Rn and its progeny.

Assessment of radon levels in multistory buildings on example of eight Russian cities

In this work, the results of radon concentration measurements in samples of multi-storey apartment buildings in eight large cities of Russia are analyzed. Two samples, depending on the year of construction of the building – before and after 2000, were formed in each city on the basis of a quasi-random approach. Radon concentration measurements were performed using radon radiometers equipped with the CR-39 solid-state nuclear track detector. In the flats of multi-storey buildings, two radiometers were installed and flat’s average radon concentration was calculated. The exposure period for the radon radiometers was three months. To estimate the average annual radon concentration, seasonal coefficients calculated for the primary radon entry from building materials were used. In total, radon concentration measurements were carried out in 1032 flats. It was assumed that the combined sample for the cities of Ekaterinburg, Krasnodar, Nizhny Novgorod, Novosibirsk, Tyumen, and Chelyabinsk is representative for the multi-storey buildings in non-capital cities of Russia. The following arithmetic mean annual radon concentrations were obtained in samples of houses built up before and after 2000, respectively: Moscow – 17 and 21 Bq/m3; St. Petersburg – 15 and 25 Bq/ m3, the group of non-capital cities – 25 and 31 Bq/m3. Taking into account the contribution of each group of buildings to the general urban housing stock, the parameters characterizing the radon concentration in multi-storey multi-apartment urban buildings in Russia were calculated as follows: arithmetic mean 25 Bq/ m3; geometric mean 21 Bq/m3; the geometric standard deviation is 1.81. In general, exposure to indoor radon in multi-storey urban buildings in Russia is low both in terms of average value and range of concentrations. There is a tendency towards an increase in indoor radon exposure of the population in new buildings, which is associated with the introduction of construction technologies that increase the energy efficiency of buildings.

Study on the measurement of high energy neutrons using Zirconium capped CR-39 (Zr-CR-39) combined detector - Monte Carlo simulation and experimental validation

Neutron measurement, be it dose or fluence is a challenging field in high energy accelerators where the neutron energy varies from thermal to high-energy neutrons usually extending beyond 20 MeV. CR-39 SSNTD (Solid State Nuclear Track Detector) used in neutron measurements has near flat energy response in the range of 500 keV to 10 MeV. By capping the CR-39 with a suitable converter such as Zirconium (Zr), it's response can be enhanced in the higher neutron energy ranges (beyond 10 MeV). Zr has significant (n,2n) cross-section of ∼1 b in the neutron energy range of 10–20 MeV. Hence, when high energy neutrons impinge on Zr, neutrons of lower energy are produced by (n,2n) reactions, which create additional recoil proton tracks in CR-39. At higher neutron energies (>20 MeV) additional tracks can also be created due to other charged secondaries such as deuteron, triton, alphas and recoil carbon and oxygen. The enhancement in track density of CR-39 in presence of Zr as compared to that of bare CR-39 is termed as the Total Enhancement Factor (TEF). Monte Carlo simulations with FLUKA and GEANT4 codes are used to optimize the Zr converter thickness with 14 MeV and 20 MeV, and are also verified with measurements. At an optimum converter thickness of 1 mm, FLUKA and GEANT4 Monte Carlo codes were used to observe the enhancement in the response of the combined detector (Zr-CR-39) against the bare detector for different mono-energetic neutron beams in the range 14 MeV - 1 GeV. The enhancement obtained for Zr converter are also compared with Lead (Pb) converter. Experimental studies were carried out to validate the simulations by irradiating Zr-CR-39 to 14 MeV, 20 MeV and high energy neutrons spectra available at CERF facility. Measured TEF values are 1.27, 2.5 and 7.85 for 14 MeV, 20 MeV and CERF neutrons spectra respectively. Results of simulations and measurements are found to be in agreement within 20%.

Indoor Radon Monitoring in Kindergarten and Primary Schools in South Italy

Humans are mostly exposed to ionizing radiation through radon and its decay products. The results of indoor radon measurements in 39 kindergartens and primary schools in the Campania region of southern Italy are presented in this paper. The survey was carried out with CR-39 solid-state nuclear track detectors (SSNTDs). Radon concentrations were measured and ranged from 11 to 1416 Bq/m3, with a geometric mean of 77 Bq/m3 and a geometric standard deviation of 2. The findings revealed that 70% of the measures were below the WHO recommended level of 100 Bq/m3 and that 97 percent of the measurements were below the 300 Bq/m3 level set by Italian law.

A study on the optimization of processing parameters of boron-doped CR-39 solid-state nuclear track detectors for response to thermal neutrons

The methodology for personnel monitoring of neutrons in the intermediate and fast energy range using CR-39 solid-state nuclear track detectors (SSNTDs) is well established. This study presents the dosimetric response of boron-doped (carborane) CR-39 detector for the measurement of thermal neutrons. It includes optimization of etching process, minimum detection limit (MDL), and thermal neutron sensitivity. Duration of low frequency (100 Hz) and high frequency (3.5 kHz) for elevated temperature electrochemical etching was optimized as 4 h and 50 minutes respectively, and used for the response characteristic study. The measured thermal neutron sensitivity and MDL were 743 ± 13 tracks cm−2 mSv−1 and 0.02 mSv, respectively. This study is useful for thermal neutron monitoring in reactor, accelerator, and all other nuclear facility environment.

Response of nuclear track detector CR-39 to low energy muons

The effectiveness of the PolyAllyl Diglycol Carbonate (PADC) etched solid state nuclear track detector (SSNTD), commonly known as CR-39, as a muon detector is assessed. CR-39 is successfully used to detect higher rest mass particles such as neutrons and protons, and is, for example, widely used in neutron dosimetry applications. CR-39 is generally accepted as being less suitable to detect lower rest mass particles such as muons, and especially electrons, due mostly to their reduced momenta and consequently, reduced stopping power. However, there has been some evidence that CR-39 may have application in the detection of cosmic ray muons. Monte Carlo simulations indicate that CR-39 can detect muons with energies up to 2.8 MeV. Experimental data to demonstrate the ability of CR-39 to detect muons was acquired using the MuSR spectrometer station at the ISIS Neutron and Muon Source. Pits deposited in CR-39 generated by positive muons from the beamline have been characterised and compared with pits deposited by protons and neutrons from other sources. The extent to which a CR-39 SSNTD can discriminate muons from particles with different momenta and rest masses is discussed.

Fluence enhancement of a 4 MeV-C4+ ion beam transmitted through a cylindrical glass channel after charging

We have developed a glass channel to guide ions heavier than protons and alpha particles with kinetic energies of several MeVs. The fluence of a 4 MeV-C4+ ion beam transmitted through the cylindrical glass channel (CGC) was measured by counting the number of etch pits using a CR39 solid-state nuclear track detector. After charge of the CGC using the incident ions with 31 nC, the fluence of the transmitted ions increased by 23%–26% at an angle of 0° with respect to the ion beam axis, compared to that before the charging process. In this case, the kinetic energy of the ions transmitted through the CGC maintained the incident kinetic energy of 4.0 MeV in absence of preceding charge up.

Radon Survey in Bank Buildings of Campania Region According to the Italian Transposition of Euratom 59/2013.

222Rn gas represents the major contributor to human health risk from environmental radiological exposure. In confined spaces radon can accumulate to relatively high levels so that mitigation actions are necessary. The Italian legislation on radiation protection has set a reference value for the activity concentration of radon at 300 Bq/m3. In this study, measurements of the annual radon concentration of 62 bank buildings spread throughout the Campania region (Southern Italy) were carried out. Using devices based on CR-39 solid-state nuclear track detectors, the 222Rn level was assessed in 136 confined spaces (127 at underground floors and 9 at ground floors) frequented by workers and/or the public. The survey parameters considered in the analysis of the results were: floor types, wall cladding materials, number of openings, door/window opening duration for air exchange. Radon levels were found to be between 17 and 680 Bq/m3, with an average value of 130 Bq/m3 and a standard deviation of 120 Bq/m3. About 7% of the results gave a radon activity concentration above 300 Bq/m3. The analysis showed that the floor level and air exchange have the most significant influence. This study highlighted the importance of the assessment of indoor radon levels for work environments in particular, to protect the workers and public from radon-induced health effects.

Radon alpha track counting on solid state nuclear track detector by an ImageJ-based software macro

Radon (222Rn) is a radioactive gas emanating from geological materials. Inhalation of this gas is closely related to an increase in the probability of lung cancer if the levels are high. The usual methodology for the quantification of radon by passive methods is the use of etched solid-state nuclear track detectors, frequently in combination with optical microscopes or image scanning for image acquisition and software-based image processing for track counting. Currently available commercial instrumentation, as the Radosys microscopy system, is quite expensive, so the development of alternative methodologies is desirable.In this work, a simple, fast and low-cost image acquisition system for the determination of tracks in chemically etched CR-39 solid-state nuclear track detectors to quantify 222Rn alpha tracks has been proposed. The image of the detector surface is obtained by a conventional light stereoscopic microscope, transmitted by a CCD camera into the computer, and analyzed by the ImageJ open-source software. This methodology was employed to analyze 45 samples collected in dwellings and caves located in the region of Extremadura (Southwest Spain). Results show a good correlation coefficient of r2 = 0.98 between the reference and purposed methodology and excellent repeatability, demonstrating that the system enables routine counting tracks for radon measurement as an alternative to the Radosys microscopy instrument.

Assessment of environmental health risks due to indoor radon levels inside workplaces in Sudan

ABSTRACT The main objective of this study is to assess the environmental health risks due to radon gas accumulation and to compare the concentrations in different kinds of workplaces in Khartoum town, Sudan. However, typical persons spend about one-third of the day at their workplace. For this purpose, a number of 231 measurements were performed in Pharmacies, Schools, Restaurants, Health-care centres, offices, shops, libraries and internet coffee shops by using CR-39 solid-state nuclear track detectors (SSNTD). Results show that the radon concentration values ranged from 16 to 103 Bqm−3, with an average of (54 ± 9) Bqm−3. The mean value of the calculated effective dose was found to be (1.35 ± 0.24) mSvy−1. The relative lung cancer risk due to radon exposure in all workplaces was found to be 1.048%. The results of the study indicated the importance of performing this type of measurement because the exposure of workers can reach high values in some workplaces.

COMPARISON OF RADON MASS EXHALATION RATE MEASUREMENTS FROM BUILDING MATERIALS BY TWO DIFFERENT METHODS.

The aim of this study is to measure the radon mass exhalation rate from common granite building materials used in the east and northeast part of Portugal. Twelve cubic shaped samples were measured. Nine of them without any coating and three coated with different materials (varnish, hydrorepellent and liquid silicone). The radon measurements were performed with two different techniques: one using passive detectors and other using an active detector. For the passive method, CR-39 solid-state nuclear track detectors were used. The active method used the RAD7 DURRIDGE detector. Radon mass exhalation rates obtained from both methods present relatively low values in the 11-45 mBqkg-1h-1 range for the analysed samples. Concerning the coated samples, the measured values are on average four times lower than the ones without coating. Overall, the measured values for both methods present a good agreement.