Intercomparison NaI(Tl) and HPGe spectrometry to studies of natural radioactivity on geological samples (original) (raw)
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Applied Radiation and Isotopes, 2000
We implemented a laboratory apparatus based on a NaI(Tl) g-ray spectrometer for the assessment of naturally occurring radioactive materials. This apparatus is devoted to the quantitative determination of U, Th and K in rock and soil samples. We analysed the calibration procedures with particular emphasis to factors which aect accuracy and detection limits. A ®rst series of measurements were compared to those obtained by means of high energy g-ray spectrometry. A discussion was made on factors restricting the approach based on scintillation spectrometry, such as secular equilibrium and radon encapsulation. 7
Journal of Radioanalytical and Nuclear Chemistry, 2008
High-resolution gamma-spectrometry provides fast, accurate, non-destructive isotopic analysis of natural radionuclides in environmental samples. Low energy HPGe detectors (30%) with resolution less than 2.0 keV at 1332 keV of 60 Co and with linked analytical software, provide good peakto-background performance and accurate unfolding of multiplet regions. A procedure regarding high-resolution gamma-spectrometry measurements of naturally occurring radioactive samples is presented here including calibration, background interference, self-absorption, practical considerations and validation with respect to IAEA reference materials. Recommended peaks for quantitative measurements, deriving from the analysis of observed spectral interferences as well as from radioactive equilibrium considerations, are reported.
The natural radioactivity of soil at Nineveh Province has been studied in this paper. The radioactivities of 19 soil samples have been measured with NaI(Tl) detector. The radioactivity concentrations of, 226Ra , 232Th ,214Pb and 40K ranged from, 17.02 to 40.98 Bq/kg, 11.22 to 32.65 Bq/kg,8.46 to 16.00 Bq/kg and from 206.51 to 509.56 Bq/kg respectively. In order to evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity ,the absorbed dose rate, the annual effective dose rate, internal and external hazard indices , gamma index, alpha index, excess life time cancer risk and finally annual gonadal dose equivalent have been calculated. The study provides background radioactivity concentrations in Nineveh Province. Specific activity concentrations in ten soil samples of selected regions in Nineveh province were analyzed for the natural radioactivity of 226Ra, 232Th,214Pb and 40K using γ-spectroscopy based on highpurity germanium detector with an efficiency of 40%. The activity concentrations of natural radionuclides 226Ra,232Th ,214Pb and 40K were found to range from 16.21 Bq/kg in (Al-Medan district) (S9) to 38.83 Bq/kg in( Sinjar district) (S1)with an average value of value of 32.52±6.48 Bq/kg , 8.53 Bq/kg in (Al-Medan district) (S9) to 28.37Bq/kg in (Rabeaa district)(S2) with an average value of 20.30±5.36 Bq/kg, 8.13 Bq/kg in (Al-Medan district) (S9) to 18.22 Bq/kg in ( Sinjar district) (S1) with an average value of 14.78± 2.97and 236.03 Bq/kg in (Telkaif district) (S5) to 613.11 Bq/kg in (Rabeaa district) (S2) with an average value of 378.93± 123.29 Bq/kg. The radium equivalent activity, absorbed gamma dose rate, annual effective dose equivalent , gamma index , alpha index ,internal and external hazard indices, excess life time cancer risk and annual gonadal dose equivalent associated with the natural radionuclides were calculated.
The natural radionuclides 238 U, 232 Th are embedded in geological materials in low quantities, which continuously emit ionizing radiations through the various daughter products of the decay chain. In the present work the performance of the newly installed 4 "x4" Nai(Tl) based gamma ray spectrometer in our laboratory was studied for its use in environmental radioactivity measurements. Standard procedure was followed for the collection and preparation of sample for gamma spectrometric measurements. The spectrum was analyzed using a PC based 1 k MCA (winTMCA 32 scinti SPEC). The analysis of complex spectra from the detector due to 238 U, 232 Th and 4°K was carried out by least squares method. The same samples were also analyzed using a high resolution HPGe detector based gamma spectrometer and the results obtained were in agreement, validating the method of analysis of environmental radioactivity using Nal(TI) detector and subsequent analysis of spectral data by least squares method. It is also important to note that Nal (TI) detector can be used instead of HPGe detector, which is very costly and difficult to maintain in remote areas. Though the resolution ofNal (Tl) detector is poor, it is more efficient for the higher energy detection, which also contributes to improved detection limits for natural radionuclides.
Physics Access, 2021
Qualitative analysis of radionuclides requires the use of reliable gamma-ray detection system. The NaI(Tl) detector has been widely used and still one of the most used detectors today. It is therefore imperative to validate the reliability of the 5x5 cm2 NaI(Tl) gamma spectrometry system used in carrying out gamma-ray analysis of soil samples in the Radiation and Health Laboratory, Federal University of Agriculture Abeokuta, Nigeria. The gamma ray spectrometer is housed in a 5 cm thick cylindrical lead shield. Calibration was executed using standard materials produced under the auspices of the International Atomic Energy Agency (IAEA). Resolution and detection limit (LD) of the detector were determined using full width at half the maximum of the energy peak of 137Cs and background signal level of the reference materials respectively. Counting efficiencies of the detector was calculated using energies of 1460 keV, 1764keV and 2615 keV for 40K, 226Ra and 232Th respectively. Secondary ...
To obtain high quality of results in gamma spectrometry, it is necessary to select the best HPGe detector for particular measurements, to calibrate energy and efficiency of gamma detector as accurate as possible. To achieve this aim, the convenient detector model and gamma source can be very useful. The purpose of this study was to evaluate the soil specific activity using two HPGe model (BEGe-6530 and GC0818-7600SL) by comparing the results of the two detectors and the technics used according to the detector type. The relative uncertainty activity concentration was calculated for 226Ra, 232Th and 40K. For broad energy germanium detector, BEGe-6530, the relative uncertainty concentration ranged from 2.85 to 3.09% with a mean of 2.99% for 226Ra, from 2.29 to 2.49% with a means of 2.36% for 232Th and from 3.47 to 22.37% with a mean of 12.52% for 40K. For GC0818-7600SL detector, it was ranged from 10.45 to 25.55% with a mean of 17.10% for 226Ra, from 2.54 to 3.56% with a means of 3.10% for 232Th and from 3.42 to 7.65% with a mean of 5.58% for 40K. The average report between GC0818-7600SL model and BEGe-6530 model was calculated and showed the mean value of 3.36. The main study was based on the following points: •Determination of The relative uncertainty activity concentration of 226Ra, 232Th, and 40K •Determination of the relative uncertainty related to the radium equivalent activity to compare the performance of the two detection systems •Proved that the activity concentration determination in gamma spectrometry depended on the energy range emitted by a radionuclide. This study showed that the standard deviation measurement was less important to the result realized with BEGe-6530 HPGe model. Our findings were demonstrated that the results of the Broad Energy Germanium detector were more reliable.
Applied Radiation and Isotopes, 2016
We organized the first proficiency test on radioactivity measurement in Turkey. Radioactivity measurement capabilities of the laboratories in Turkey were examined. Twelve participant laboratories reported results with 49% acceptable scores. Labs using HPGe reported more accurate and precise results than the ones using NaI. Participants need more practice and training for their staff.
Elemental analysis using natural gamma-ray spectroscopy
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1994
A gamma-ray spectroscopy setup has been recently established to measure the natural gamma-ray activity from potassium ( 4°K), uranium (238 U), and thorium (Z32Th) isotopes in rock samples of oil well-logs. The setup mainly consists of a shielded 135 cm3 Hyper Pure Germanium (HPGe) detector, a 5 in . X 5 in . NaT(TI) detector and a PC based data acquisition system . The core samples, with 70-100 g weight, have cylindrical geometry and are sealed such that radon gas from 238U decay would not escape from the sample. For room background subtraction, pure quartz samples identical to core samples were used . The sample is first counted with the HPGe detector to identify the elements through its characteristics gamma rays . Then the elemental concentration is determined by counting the sample with a Nat detector. In order to determine the absolute concentrations, the sample activity is compared with the activities of standards supplied by NIST and IAEA . The concentration of 238U and Z32Th has been determined in ppm range with that of°K in wt .% .
The International Conference on Chemical and Environmental Engineering
Natural radioactivity exists everywhere around us in soil, air, water, and atmosphere and even in our bodies. Radiological background levels especially for vital locations are of great importance to our country nuclear program. EL-Dabaa site, at which the first Egyptian nuclear power plant will be constructed, is strategic area to be monitored before the beginning of the plant experimental and commercial operation. The aim of this study is to evaluate the radioactivity levels and its radiological hazard indices especially in the zones around the NPPs; exclusion zone, low population zone and high population area (El-Dabaa old and new town). Many soil and shore sediment samples were collected from these areas. They were prepared and then analyzed using HpGe spectrometer. The calculations of activity concentration (Ac) of natural radionuclides 238 U, 232 Th decay series and 40 K were carried out. Based on the results obtained, the hazard indices (air absorbed gamma dose rate D , annual effective dose E , excess life time cancer risk ELCR) indoor and outdoor also (Ra equivalent Raeq and internal and external hazard index Hin,Hex) also (gamma index I and alpha index I) were estimated. The man-made radionuclide 137 Cs was also measured. The results are tabulated, plotted, discussed and compared with the national and international levels and limits.
A methodology for expanding the use of NaI(Tl) based spectrometry in environmental radioactivity measurements, 2018
A methodology that extends the usability of low and medium resolution γ-ray detectors to a wide range of energies that appear in environmental radioactivity measurements is described. Results of the implementation of the methodology in the analysis of 20 granite samples measured with a (3″ × 3″) NaI(Tl) are presented. A comparison with the activity results obtained by a high-resolution detector (HPGe) for two samples was found in good agreement, within the uncertainties, validating the results of the proposed method.