Tl Detector Research Articles

ASSESSMENT OF DOSE RATE USING GAMMA RAY OBSERVATIONS IN THE MINING WASTE SAMPLES OF SIMBERI GOLD MINE IN PAPUA NEW GUINEA

The specific activity of natural radionuclides were measured by gamma ray spectrometry with NaI(Tl) detector in the mining waste soil samples collected from Simberi gold mine in New Ireland province of Papua New Guinea. The isotope concentrations of 238U and 232Th in Simberi soil samples are 10.7 and 41.3 ppm respectively whereas the world average values are 2.64 and 11.1 ppm respectively. The average Radium equivalent activity in Simberi samples is 372.2±81.4 Bq/kg which is observed to be higher than the threshold safe value of 370 Bq/kg. The average internal hazard index for Simberi samples is found to be 1.4 which is higher than the maximum permissible value of 1.0. The Excess Lifetime Cancer Risk (ELCR) is calculated to be 0.00553±0.00122 in Simberi whereas the world average value is 0.00145. Radiation in Simberi is found to be higher which may be because Simberi is situated in the volcanic region of Papua New Guinea

International comparison of activity measurements of a solution of 51Cr

Main textA bilateral comparison between LNE-LNHB, France and the RC POLATOM, Poland on activity measurements of the 51Cr solution was organized in 2022 as the EURAMET project No 1554 and registered as EURAMET.RI(II)-K2.Cr-51 key comparison. In both laboratories, primary activity measurements techniques based on 4π(LS)-γ coincidence and anti-coincidence counting methods were used. LNE-LNHB also performed indicative measurements in a large-well NaI(Tl) detector using the 4πγ method. The final result of the comparison in RC POLATOM was the weighted mean of the results of the 4π(LS)-γ coincidence method and the 4π(LS)-γ anti-coincidence method, and in the LNE-LNHB - the value obtained by the 4π(LS)-γ anti-coincidence method. The power-moderated mean of the final results values was calculated. An additional ampoule containing the same 51Cr solution was sent to the BIPM in order to link the results achieved in the bilateral comparison to the BIPM SIR reference system.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Distribution of radionuclides and activity utilisation index estimation of construction materials using in Mangalore district, India

ABSTRACT The present investigation involved the collection of various construction materials from several sites throughout the Mangalore District, Karnataka, India. The concentration of radionuclides in each sample was then determined using a NaI(Tl) detector. The passive ‘Can’ technique method was used to determine the rate of radon exhalation in the collected samples. The activity concentration of 40K ranges from 36.53 Bq kg−1 to 80.68 Bq kg−1. The activity concentration of 226Ra ranges from 23.30 Bq kg−1 to 80.87 Bq kg−1. The 232Th activity concentration found to be lowest is 15.06 Bq kg−1 and a maximum of 38.65 Bq kg−1 in different samples. The estimated Activity Utilisation index (AUI), dose rate (D) and gamma index (Iγ) which is lower than the recommended limit. The hazard index values are below the Indian, World average and below the safety limit, which indicates that construction materials are safe to use for construction purposes. The present investigation gives insight on radiation hazards to the human population used in the selected location.

Application of the LPE-Grown LuAG: Ce Film/YAG Crystal Composite Thermoluminescence Detector for Distinguishing the Components of the Mixed Radiation Field.

Single-crystalline films (SCFs) of the LuAG: Ce garnet grown using the liquid-phase epitaxy method onto YAG single-crystal (SC) substrates were investigated for possible applications as composite thermoluminescent (TL) detectors. Such detectors may help to register the different components of ionizing radiation fields with various penetration depths, e.g., heavy charged particles and gamma or beta rays. It was found that the TL signal of LuAG: Ce SCF sufficiently differs from that of the YAG substrate concerning both the temperature and wavelength of emissions. Furthermore, even by analyzing TL glow curves, it was possible to distinguish the difference between weakly and deeply penetrating types of radiation. Within a test involving the exposure of detectors with the mixed alpha/beta radiations, the doses of both components were determined with an accuracy of a few percent.

Experimental evaluation of gamma-rays shielding properties of ceramic materials used in dentistry

The radiation shielding properties of some ceramic materials have been measured and obtained results were compared with the simulation. Gamma rays with energy of 662, 1173, and 1332 keV produced from 137Cs and 60Co radioactive sources were utilized in the experimental part of this work to measure linear attenuation coefficients (LAC). A gamma spectrometer with a 3″ × 3″ NaI(Tl) detector, high-voltage electrical components, a preamplifier, an amplifier, and 16384-channel Multi-Channel Analyses (MCA). For simulation the Monte Carlo method to compute and evaluate the linear attenuation coefficients of ceramic materials employed in the human body as synthetic or natural materials. In the simulations conducted with the Gamos 6.2 software, a mono-energetic point photon source geometry between 1 keV and 15 MeV was employed in the computational phase of the investigation by focusing a parallel photon beam toward the absorber material.

Appearance of Chance Coincidence in Attenuation Measurements Carried out by using Coincidence Technique

The appearance of chance coincidence in attenuation measurements using coincidence technique is investigated. A two 3"*3" NaI(Tl) detector coincidence spectrometer with 0.5 μ Ci Na-22 source were used. Two different materials with different forms, namely mixed metallic powders and Fe-sheets are used. The ratio of chance counts to total real coincidences in annihilation peak had ranged between (0.007-0.013) and (0.011-0.036) for the different thicknesses of the two materials mentioned respectively. The coincidence linear attenuation coefficients due to the chance coincidence at 1274keV were 0.1 and 0.38 cm-1 for the two materials assuring the proportionality with energy. When the chance coincidence counts were treated as being "lost" from real coincidences and added again to the latter, no change were observed in attenuation coefficient at annihilation peak from that calculated before taking accidental counts into consideration.

Distribution dynamics and descriptive statistical analysis of radionuclides in the farmland soils near mining areas in Southwestern Nigeria.

Human exposure to ionizing radiation in the environment is mainly due to naturally occurring radionuclides in the soils, building materials and rocks, but the level may vary depending on the anthropogenic activities prevalent in each location. Presently, in Nigeria, there are concerns due to environmental health implications of all sorts of mineral mining and processing spreading across the southwestern states of the country. This work determines the activity concentrations of naturally occurring radionuclide materials (NORMs) in the farmland soil with the aim of evaluating the radiation hazards. A total of 200 composite soil samples were taken from five states in the southwest of Nigeria, close to active mining sites at the root (0.2m) and at deep planting zones (0.5m) for analysis by gamma-ray spectrometry using NaI(Tl) detector. The activity concentrations of natural radionuclides in the composite soil samples were determined to vary in the order of 40K > 232Th > 226Ra/238U for all locations. In contrast to the other locations, Olode and Igbokoda had average radium equivalent activities (Raeq) to be 1.6 and 1.8 times, respectively, higher than the reference limit of 370 Bqkg-1. The estimated excess life cancer risk values were lower than the 0.29 × 10-3 global average value for soil by United Nations on Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and International Commission on Radiological Protection (ICRP). Negative and low skewness values of 0.61 and 1.20 were obtained for 40K in Itagunmodi, and also 0.47 and 0.66 for 232Th were obtained in Sagamu. The kurtosis analysis of the activity concentrations was low and negative for soil at Itagunmodi for 40K and 226Ra/238U; Olode for 40K and 232Th; and Igbokoda for 226Ra/238U and 232Th where mining activities are commonly practiced. The variation in the results has been attributed to different agriculture practices and artisanal mining operations in each location.

Multifunctional PCz/BaO nanocomposites: Ionizing radiation shielding ability and enhanced electric conductivity

The present study deals with the production of multifunctional polymer-based nanocomposites having the ability of ionizing radiation shielding and enhanced electric conductivity. In this context, it is aimed to obtain a new environmentally-friendly lead-free material with both high electric conductivity and ionizing radiation shielding features by reinforcing polycarbazole (PCz), a conductive polymer with BaO nanoparticles having a high effective atomic number. PCz matrix and BaO nanoparticles have been prepared by polymerization and co-precipitation methods, respectively. The surface morphology of the PCz matrix and nano BaO particles have been characterized by SEM and TEM images. Additionally, the optical band gaps of the samples have been calculated by using UV–visible spectroscopy. The lowest optical bandgap i.e. the highest electric conductivity has been observed for the 10 wt% BaO nanoparticle doped composite. On the other hand, the ionizing radiation shielding abilities of the samples have been evaluated in the context of mass attenuation coefficient, half-value layer, mean free path, effective atomic number, and effective electron density determined both experimentally and theoretically. Experimental measurements have been carried out by using NaI(Tl) detector and point radioactive sources (Ba-133, Cs-137, and Co-60) in the narrow beam geometry. The theoretical calculations have been performed by WinXCom software. A reasonable agreement between the experimental and WinXCom results has been found. Consequently, it has been determined that the maximum radiation shielding ability has been detected against 81 keV radiation for the PCz/30 wt% BaO nanocomposite. The composite has also a lower bandgap than pristine PCz. In this respect, the PCz/30 wt% BaO nanocomposite can have a promising potential in both medical and electronic applications that require high electric conductivity and ionizing radiation shielding ability.

Development of the Composite Thermoluminescent Detectors Based on the Single Crystalline Films and Crystals of Perovskite Compounds.

This work is dedicated to the development of new types of composite thermoluminescent detectors based on the single crystalline films of Ce-doped GdAlO3 perovskite and Mn-doped YAlO3 and (Lu0.8Y0.2)AlO3:Mn perovskites as well as Ce and Pr-doped YAlO3 single crystal substrates. These detectors were obtained using the Liquid Phase Epitaxy growth method from the melt solution based on the PbO-B2O3 fluxes. Such composite detectors can by applied for the simultaneous registration of different components of mixed ionization fluxes using the differences between the thermoluminescent glow curves, recorded from the film and crystal parts of epitaxial structures. For creation of the new composite detectors, we considered using, for the film and crystal components of epitaxial structures (i) the different perovskite matrixes doped with the same type of activator or (ii) the same perovskite host with various types of activators. The thermoluminescent properties of the different types of epitaxial structures based on the abovementioned films and crystal substrates were examined in the conditions of β-particles and X-ray excitation with aim of determination of the optimal combination of perovskites for composite detectors. It was shown that, among the structures with all the studied compositions, the best properties for the simultaneous thermoluminescent detection of α- and X-rays were the GdAlO3:Ce film/YAlO3:Ce crystal epitaxial structure.

Calibration of the comet assay using ionising radiation

Several trials have attempted to identify sources of inter-laboratory variability in comet assay results, aiming at achieving more equal responses. Ionising radiation induces a defined level of DNA single-strand breaks (per dose/base pairs) and is used as a reference when comparing comet results but relies on accurately determined radiation doses. In this ring test we studied the significance of dose calibrations and comet assay protocol differences, with the object of identifying causes of variability and how to deal with them. Eight participating laboratories, using either x-ray or gamma radiation units, measured dose rates using alanine pellet dosimeters that were subsequently sent to a specialised laboratory for analysis. We found substantial deviations between calibrated and nominal (uncalibrated) dose rates, with up to 46% difference comparing highest and lowest values. Three additional dosimetry systems were employed in some laboratories: thermoluminescence detectors and two aqueous chemical dosimeters. Fricke’s and Benzoic Acid dosimetry solutions gave reliable quantitative dose estimations using local equipment. Mononuclear cells from fresh human blood or mammalian cell lines were irradiated locally with calibrated (alanine) radiation doses and analysed for DNA damage using a standardised comet assay protocol and a lab-specific protocol. The dose response of eight laboratories, calculated against calibrated radiation doses, was linear with slope variance CV= 29% with the lab-specific protocol, reduced to CV= 16% with the standard protocol. Variation between laboratories indicate post-irradiation repair differences. Intra-laboratory variation was very low judging from the dose response of 8 donors (CV=4%). Electrophoresis conditions were different in the lab-specific protocols explaining some dose response variations which were reduced by systematic corrections for electrophoresis conditions. The study shows that comet assay data obtained in different laboratories can be compared quantitatively using calibrated radiation doses and that systematic corrections for electrophoresis conditions are useful.

Investigating NORMs transfer factor in food items harvested from Gerado agricultural soil, and their related health hazards Dessie, Ethiopia

ABSTRACT In this study, the activity concentration of NORMs were measured using gamma spectrometer, based on NaI(Tl) detector with Maestro-32 installed computer soft- ware. Accordingly, the average activity concentrations of 232Th, 238U, and 40K in soil samples were found 17.85±0.50, 40.16±0.54, and 271.46±0.07, respectively, which are lower than the average world recommended values given by UNSCEAR 2000 for Th and K, but higher for U decay series. In the same way, activity concentration of NORMs in food items cultivated from the irrigation site were measured and the highest activity concentrations were observed in bean samples. The transfer factors of 232Th, 238U and 40K from soil to food items were computed based on the measured activity values, and in most food items it is observed above the world average values. The consecutive chronic daily intake via ingestion for some food items from samples are also above the permissible limit. The transfer factor from Gerado agricultural soil to plant exceed the world average values in the cases of 232Th and 238U according to our study.

Estimating the mineral density of trabecular bone using Compton scattering

This study proposes a technique based on Compton scattering to estimate trabecular bone mineral density (TBMD), which is important for understanding bone strength, and hence, is pivotal for estimating the condition of the bone. Bone phantoms (a mixture of paraffin wax and bone powder) with various concentrations of bone ash were prepared to simulate the trabecular bone. These samples were exposed to primary gamma photon flux from a137Cs (222 GBq) radioisotope source one after the other, and the scattered photon flux was detected using an NaI(Tl) detector. The presence of the cortical bone (using aluminum sheets) and fat (tertiary butyl alcohol) around the trabecular bone was also studied to determine whether the TBMD measurements had been affected. The correlation between bone ash contents and the intensity of Compton scattering was high with a coefficient of 0.97. The outcomes suggest that TBMD is independent of the presence of the cortical bone and overlying fat, with a statistical uncertainty of ±0.3% in the count rate. The intensity of Compton scattering increased by only 1.5% when the thickness of the aluminum sheet (simulating the cortical bone) becomes was increased by four times, and by less than 5% when the bone phantom was surrounded by tertiary butyl alcohol.

Soil-to-plant transfer of 40K, 238U and 232Th and radiological risk assessment of selected mining sites in Nigeria

One of the major route through which humans are exposed to ionizing radiation is via food chain, which is consequent of soil-to-plant transfer of radionuclides. This work reported the activity concentrations of 40K, 238U and 232Th in samples of water, soil and guinea corn grains collected from Beryllium and Gold mining sites in Kwara, Nigeria. In-situ measurements at approximately 1 m in the air was carried out using a well-calibrated portable Gamma Spectrometer (Super Spec RS-125), while the soil, water and the guinea corn samples were analyzed using a ‘3 × 3’ inch lead-shielded NaI (Tl) detector. The measured activity concentrations of the natural radionuclides in the soil from both mines are lower than the in-situ measurements. This was attributed to the contribution from other terrestrial materials on-site. The estimated mean transfer factors (TFs) for 40K, 238U and 232Th are 0.21, 0.17 and 0.31, and 0.46, 0.19 and 0.28 respectively for the Beryllium and Gold mining sites. While the TFs for 238U and 232Th exceeded the mean value of 0.0062 and 0.0021 for 238U and 232Th respectively, the TFs for 40K are well below the 0.74 for cereals grains provided by International Atomic Energy Agency (IAEA). The radiation impact assessment using the Monte Carlo simulations reveals values that were generally less than the global average values provided by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Hence, the risk of cancer inducement due to radiation exposure is within the acceptable limits for both mining sites.

Low-energy Gamma Unfolding Using NaI(Tl) Geant4 Detector Model and GRAVEL Code

Abstract: In the field of gamma spectrometry with calibrated NaI(Tl) 3” × 3” γ-ray spectrometer, the correction of the photo-peak region of the original spectrum was discussed. In the present paper, GRAVEL algorithm based on Bayes theorem was used to test the unfolding process at low energetic interval, where Compton continium and background contributions are dominant. The simulated response matrix was constructed from mono-energetic γ-ray using validated Geant4 code. The calculated spectrum was compared with experimental 133Ba gamma spectrum. The compared activities were found in good agreement in 4.10 % order. Keywords: Spectrum unfolding, Gamma-ray spectra, Geant4 simulation, NaI(Tl) detector. PACS: NaI(Tl): Sodium iodide (NaI) detector activated by thallium (Tl), Geant4: GEometry ANd Traking, FWHM: Full Width at Half Maximum.

Impact of respiratory motion on lung dose during total marrow irradiation.

We evaluated the impact of respiratory motion on the lung dose during linac-based intensity-modulated total marrow irradiation (IMTMI) using two different approaches: (1) measurement of doses within the lungs of an anthropomorphic phantom using thermoluminescent detectors (TLDs) and (2) treatment delivery measurements using ArcCHECK where gamma passing rates (GPRs) and the mean lung doses were calculated and compared with and without motion. In the first approach, respiratory motions were simulated using a programmable motion platform by using typical published peak-to-peak motion amplitudes of 5, 8, and 12mm in the craniocaudal (CC) direction, denoted here as M1, M2, and M3, respectively, with 2mm in both anteroposterior (AP) and lateral (LAT) directions. TLDs were placed in five selected locations in the lungs of a RANDO phantom. Average TLD measurements obtained with motion were normalized to those obtained with static phantom delivery. The mean dose ratios were 1.01 (0.98-1.03), 1.04 (1.01-1.09), and 1.08 (1.04-1.12) for respiratory motions M1, M2, and M3, respectively. To determine the impact of directional respiratory motion, we repeated the experiment with 5-, 8-, and 12-mm motion in the CC direction only. The differences in average TLD doses were less than 1% when compared with the M1, M2, and M3 motions indicating a minimal impact from CC motion on lung dose during IMTMI. In the second experimental approach, we evaluated extreme respiratory motion 15 mm excursion in only the CC direction. We placed an ArcCHECK device on a commercial motion platform and delivered the clinical IMTMI plans of five patients. We compared, with and without motion, the dose volume histograms (DVHs) and mean lung dose calculated with the ArcCHECK-3DVH tool as well as GPR with 3%, 5%, and 10% dose agreements and a 3-mm constant distance to agreement (DTA). GPR differed by 11.1 ± 2.1%, 3.8 ± 1.5%, and 0.1 ± 0.2% with dose agreement criteria of 3%, 5%, and 10%, respectively. This indicates that respiratory motion impacts dose distribution in small and isolated parts of the lungs. More importantly, the impact of respiratory motion on the mean lung dose, a critical indicator for toxicity in IMTMI, was not statistically significant (p > 0.05) based on the Student's t-test. We conclude that most patients treated with IMTMI will have negligible dose uncertainty due to respiratory motion. This is particularly reassuring as lung toxicity is the main concern for future IMTMI dose escalation studies.

Evaluation of radioactivity concentration of some selected mineral rocks from Mayo-Belwa Local Government Area of Adamawa State, Nigeria

Radiation from natural sources is constantly present around people and their surroundings. Natural Occurring Radioactive Materials (NORM) present in rock, soil and underground water are the major sources of this radiation. In this study, radioactivity concentration of 238U, 232Th, and 40K from Ten (10) different Granite (GN), Gneiss (GS), and Migmatite (MG) rocks samples obtained from Mayo Belwa Local Government Area of Adamawa State were evaluated using a well calibrated and shielded Canberra 3 x 3 inch NaI(Tl) detector at the National Institute of Radiation Protection and Research (NIRPR), University of Ibadan. Rock samples were cleaned, pulverised and placed in the detector for counting, and based on standard expressions, the radionuclide content of the granite rock samples were evaluated. The result shows that the activity concentration of 238U, 232Th, and 40K in GN samples varies from 62.44 – 117.67 Bq/kg, 76.59 – 165.58 Bq/kg, and 688.03 – 1472.42 Bq/kg with corresponding mean of 74.59 ± 3.12, 104.41 ± 3.12, and 950.16 ± 3.12 Bq/kg. Activity concentration of 238U, 232Th, and 40K in GS samples ranges from 19.23 – 36.49 Bq/kg, 29.06 – 49.42 Bq/kg, and 310 – 924.21 Bq/kg with corresponding mean of 28.1 ± 5.36Bq/kg, 38.92 ± 6.38 Bq/kg, and 664.21 ±178.14 Bq/kg. Activity concentration of 238U, 232Th, and 40K in MG samples ranges from 32.11 – 74.73 Bq/kg, 40.79 – 105.87 Bq/kg, and 453.34 – 1040.77 Bq/kg with corresponding mean of 50.19 ± 14.35 Bq/kg, 60.50 ± 19.96 Bq/kg, and 714.88 ± 200.37 Bq/kg. The mean activity from this study are higher than the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) global mean of 238U (32 Bq/kg), 232Th (45 Bq/kg), and 40K (420 Bq/kg) in soil and rock samples except for 238U and 232Th in GS samples which are lower than the recommended standards. The results signifies that usage of such rocks as building construction raw materials might pose radiological hazards in the long run. Therefore, mineral content of the rock responsible for the high radionuclide concentration should be investigated.

Evaluation of nuclear data analysis techniques for volume fraction prediction in the flow meter

Abstract The volume fraction percentage measurement in multiphase flows is a vital need in the oil, gas and petroleum industries. Thus, diverse and precise techniques should be presented for achieving this purpose. In this research, the water-oil two-phase flows were simulated using the MCNPX code in operational and real conditions in the oil district of Kharg. A single source 137Cs and a NaI (Tl) detector were used to provide the required data for volume fraction prediction. Then, the ANN, Gaussian, Linear Regression, and Fourier techniques were applied to the acquired nuclear data in order to compare and identify the suitable and precise method for predicting the volume fraction. Using the ANN, Gaussian, Linear Regression, and Fourier techniques, the volume fraction was predicted with a mean relative error percentage of less than 8.71, 10.14, 16.07, and 12.45%, respectively. Also, the root mean square error quantities were calculated 1.05, 1.18, 1.36, and 1.27, respectively. The results reveal that the ANN method has superior in comparison with the other methods.

Evaluation of different types of lithium fluoride thermoluminescent detectors for ring dosimetry in nuclear medicine

Nuclear medicine staff is primarily exposed to their fingers during radionuclide manipulation. About 20% of these workers have risk to exceed the hand dose limit. Therefore, monitoring with ring dosimeters in terms of Hp(0.07) is advised. Most ring dosimeters make use of lithium fluoride (LiF) thermoluminescent detectors (TLDs). Different types of LiF TLDs exist, each with their advantages and disadvantages. The goal of this work was to evaluate the performance of three different LiF TLD types (MCP-N, MTS-N and MCP-Ns) for ring dosimetry during manipulation of the more novel radionuclides Lu-177, Ga-68 and I-131 within radionuclide imaging and therapy, and to provide recommendations for the most accurate dosimetric follow-up of the dose to the hands. This was done by combining measurements with TLDs and theoretical modelling of the TLD responses using Monte Carlo radiation transport simulations and microdosimetric modelling of the TLD relative luminescence efficiency. It was concluded that MTS-N TLDs are best suited for measuring doses from Lu-177 and I-131 if more than 1 mm polycarbonate equivalent shielding is provided. However, MCP-N TLDs have less than 20% under-response and are thus also acceptable in case high sensitivity is important. MCP-Ns TLDs were found to be best suited for measuring doses from Ga-68, and from Lu-177 and I-131 if less than 1 mm polycarbonate equivalent shielding is provided. The recommended TLD type strongly depends on both the manipulated radionuclide and the amount of shielding between the radionuclides and the fingers (syringe thickness and potential additional shielding around the syringe). But the approach presented here for the theoretical modelling of the Hp(0.07) response can easily be applied to select the most appropriate TLD type for other radionuclides or other amounts of shielding.

Prediction of gamma ray spectrum for 22Na source by feed forward back propagation ANN model

The radiation has been used in a variety of different fields since its discovery and thus its measurement becomes vital in these industries. Different type detector may be used to measure gamma rays depends on the purposes of measurements. Gamma ray energy spectrum is an important to determine either elemental analysing of a sample or radiation shielding purposes. On the other hand, Artificial Neural Network (ANN) may be used to predict and analysing of gamma-ray spectrum. In this study, gamma ray spectrum from 22Na source detected in NaI (Tl) detector was estimated by ANN. There have been installed ten different ANN models to find the network structure that produces the best predictive value for the gamma ray spectrum NaI (Tl) Detector. Estimation study has been continued with the ANN model with be possessed of lowest error value. ANN model was created by using energy, distance and gamma-rays energy spectrum (called Io) values. In the ANN model developed using the feed forward back propagation algorithm, were used artificial neurons two in the input layer, ten in the hidden layer and one in the output layer. For the case of present work, the experimental data was used 70% for education, 20% for validation and 10% for testing. The estimated values obtained with the ANN model were compared with the experimental results and a good correlation has been found between them (R2 = 0.99).

Measurement of Radium and Radon Exhalation Rate in Marble Samples used in Al-Bayda City Market-Libya

The aim of the present study is to measure the activity concentrations of 226Ra, 222Rn, the mass exhalation rate of 222Rn, and the annual effective dose of radon in marble samples collected from Al-Bayda city local market –Libya. Samples were measured by using a low-background NaI (Tl) detector. The average activity concentrations of 226Ra and 222Rn were 72.57 Bq.kg-1 and 597.85 Bq.m-3.The radon exhalation rate in marble samples vary from 0.05-0.30 Bq.kg-1.S-1 with an average of 0.13 Bq.kg-1.S-1. The annual effective dose of radon was calculated in samples under investigation. For most samples, the values were lower than the maximum permissible dose limits. It can be concluded that marble samples under investigation do not pose any radiological hazard to the dwellers of buildings used in their construction.