keV Gamma Energy Research Articles

Experimental and theoretical evaluation of Cu–Al–Ni shape memory alloys shielding properties at the 511–1333 keV gamma energy range

Experimental and theoretical evaluation of Cu–Al–Ni shape memory alloys shielding properties at the 511–1333 keV gamma energy range

Effect Gamma-ray on structure and mass attenuation coefficient of Hydroxyapatite Ca10(PO4)6(OH)2, in Bovine Bone

Hydrothermal treatment procedures were employed, to generate hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂ ,(HAP) powder, from the femur and ribs of bovine bone samples. This investigation delves into the effect of gamma rays, from a Cs-137 activity equal to 220 µCi at integral doses of 20 kGy, on the surface structures, vibration properties, and attenuation coefficient of HAP, in the bovine femur bone and ribs. The mass attenuation coefficients for HAP powder were registered as E= 511 keV, with 1276 keV gamma energy released from the 22Na radioisotope, and 662 keV gamma energy released from the 137Cs radioactive isotope. We used the Nist XCom program to calculate the mass attenuation coefficient of HAP before and after radiation for photon energies ranging from 0 keV to 100 keV.

Radiation hard gallium oxide scintillators for high count rate radiation detection

Despite decades of materials research, the availability of appropriate crystalline radiation-hard scintillators with ultrafast decay times (∼10ns) and high light yields (>2000 ph/MeV) are still limited. In this study, we demonstrate the potential of gallium oxide (β-Ga2O3) based scintillators for high count rate applications. The low-cost rugged β-Ga2O3 scintillators were grown using the optical float zone (FZ) technique. Several dopants and growth atmospheres were used to demonstrate the balance between ultrafast primary decay time and the light yield of the scintillators. Light yields as high as 6446 ± 716 ph/MeV were obtained with 18.3 ns decay time for 662 keV gamma rays. Decay times as fast as 12ns were obtained with a 3212 ± 357 ph/MeV light yield. An excellent 662 keV gamma energy resolution of 7% was obtained using the β-Ga2O3:Ce crystals. Even with these excellent scintillation properties, the gamma radiation hardness of β-Ga2O3 crystals was better than the leading radiation-hard lead tungstate (PbWO4) crystals. Twenty-six scintillators fabricated from the grown β-Ga2O3 crystals were tested for radiation hardness with a 60Co gamma irradiation rate of 14 krad/h with a total radiation dose of 2 Mrad. The scintillation properties of these crystals remained unaffected. To date, no other scintillator has demonstrated such high radiation resistance. These FZ-grown low-cost, non-hygroscopic, and high-density β-Ga2O3 scintillators can replace the existing scintillators in many applications ranging from nuclear and high energy physics experiments to nuclear security.

Investigation of Radiation Attenuation Properties of Al-Cu Matrix Composites Reinforced by Different Amount of B4C Particles

In recent years, B 4 C particle reinforced Al matrix composite materials have been excessively used for gamma and neutron shielding regarding their neutron absorption and lightweight. In this paper, linear and mass attenuation coefficients using 80 keV, 356 keV, 137Cs (662 keV), 60Co (1173 keV,1332 keV) and 2000 keV(high energy) gamma energies for B 4 C (5-15 wt%) particle-reinforced Alumix 13 and Alumix 231 (which contains special alloy elements such as Cu and Mg) aluminum matrix composites were theoretically calculated with XCOM platform. Pair production, coherent scattering, photoelectric absorption and incoherent scattering processes besides the total attenuation coefficients for B4C (5-15 wt%) particle-reinforced Alumix 13 and Alumix 231 matrix composite materials were evaluated separately. On the other hand, half-value thickness (HVL) values and one-tenth thickness values (TVL) were also calculated to evaluate the radiation shielding effectiveness of this material excluding coherent scattering values that are frequently used in gamma ray transport theory as well as the total attenuation coefficients. Gamma attenuation curves for Al composite materials against 80 keV, 356 keV, 137Cs (662 keV), 60Co (1173 keV, 1332 keV) and 2000 keV (high energy) gamma energies were theoretically calculated and plotted for B 4 C (5-15 wt%) particle-reinforced Alumix 13 and Alumix 231 matrix composite materials. According to the obtained results for this material, radiation attenuation properties and the ability of shielding of materials were investigated. Therefore, this study is original from a variety of aspects, and its results may be used not only in nuclear technology but also in other technologies such as nano and space technology.

Monte Carlo simulation of a NaI(Tl) detector efficiency

In radiation physics and dosimetry it is important to obtain an accurate analytical result for the measurements. This could be possible by controlling of some parameters of the experimental system. The detection efficiency is one of the most important parameter and it should be known in radiation measurements.In this study, the detection efficiency of a 3″ × 3″ NaI(Tl) scintillation detector has been simulated by FLUKA code for 6 different gamma ray energies at 1, 1.5, 2, 3, 5, 9, 15 cm source to detector distance. The simulated results were compared with the measurements done at 511, 662, 835, 1173, 1275, and 1332 keV gamma energies.

Assessment of the mass attenuation parameters with using gamma-rays for manganese substituted nano hydroxyapatite

Manganese substituted hydroxyapatite nanoparticles (nMnHAp) were produced using the ultrasonic wet chemical method. The elemental analysis was performed using Scanning Electron Microscopy (SEM) with integrated Energy Dispersive X-ray Spectrometry (EDX). The mass attenuation coefficients of manganese substituted hydroxyapatite nanoparticles have been measured at 59.5 keV gamma energy emitted from 241Am radioisotope annular source with 50 mCi activity by using Ultra Low Energy Germanium Detector. These values are found to be in good agreement with theoretical values based on calculated XCOM data. Electron densities and effective atomic numbers were calculated by using the mass attenuation coefficients. Also, the mass attenuation coefficient of the real bone was determined as experimentally. The obtained results may provide information on how much radiation is transmitted through the sample when they are exposed to gamma-rays at 59.5 keV by comparing real bone.

Evaluation of gamma-ray attenuation properties of lithium borate glasses doped with barite, limonite and serpentine

Abstract The values of mass attenuation coefficient, the effective atomic number and the electron density of barite-doped, limonite-doped, serpentine-doped and undoped lithium borate glasses were obtained not only from experimental study using the narrow beam transmission method for 81, 121, 244, 276, 344, 383, 444 and 778 keV gamma energies with Hp-Ge detector, but also therotical work by WinXCom software (1 keV–105 MeV). From the obtained results, all glasses type mass attenuation coefficient values tend to decrease under the condition of increasing energy by means of varied interaction mechanism in different energy regions. In addition, the effect of chemical composition on shielding properties was also investigated. It is inferred that doping element with high atomic number improves the gamma rays shielding properties of system. Among the investigated samples, barite-doped lithium borate glasses have highest value of mass attenuation, which makes barite-doped samples good candidates for artificial radiation application where visual detection is especially required.

On the gamma spectrometry efficiency of reference materials and soil samples

The relative discrepancies between the gamma spectrometry efficiency of RGU, RGTh, RGK reference materials and some soil samples have been studied using a MCNP model of a real HPGe detector. It has been shown that, in a specified geometry, efficiencies differences depend on the sample elemental composition. The elemental compositions of RGU-1, RGTh-1 reference materials and a soil sample have been evaluated using X-Ray fluorescence (XRF) method and used in the MCNP simulation along with RGK-1 and six other soil samples with different elemental compositions to calculate their efficiencies in different gamma ray energies. To estimate the maximum relative efficiencies differences between soil samples and reference materials, five soil samples with higher attenuation properties were selected from a large data set of soils elemental compositions. The results show that the efficiency differences between soil samples and reference materials are almost ignorable for more than 100 KeV gamma energies. It strongly depends on the sample attenuation factor in the lower energies, so use of a self-attenuation correction is essential for radionuclide counting in low energies gamma rays. Results show about 8 percent discrepancy between RGU and two soil samples efficiencies in 63.2 KeV energy.

Attenuation coefficients for fibrous self-compacting concrete in the energy range of 50-3000keV

The fibrous self-compacting concrete is a high performance concrete with uniformly distributed iron fibers, developed and characterized by Maragon (2006 and 2009). Transmission measurements, with 137Cs and 60Co sources were performed for the attenuation coefficients determination for both ordinary and fibrous self-compacting concretes. The results were compared to each other and to the values found in the literature for ordinary concrete. The mass attenuation coefficient for the fibrous self-compacting concrete showed to be higher than those for ordinary concrete of about 5%, depending on the gamma energy. However, it should be noted that the density of fibrous self-compacting concrete is higher than ordinary concrete, 2.4 g/cm3 and 1.9 g/cm3 respectively, increasing still further the difference in mass attenuation coefficient. In addition to that, by using Monte Carlo simulations, with MCNP5 Monte Carlo computer code, the data was extended to the 50-3000 keV gamma energy range.

Improvement in minimum detectable activity for low energy gamma by optimization in counting geometry

Gamma spectrometry for environmental samples of low specific activities demands low minimum detection levels of measurement. An attempt has been made to lower the gamma detection level of measurement by optimizing the sample geometry, without compromising on the sample size. Gamma energy of 50–200 keV range was chosen for the study, since low energy gamma photons suffer the most self-attenuation within matrix. The simulation study was carried out using MCNP based software “EffCalcMC” for silica matrix and cylindrical geometries. A volume of 250 ml sample geometry of 9 cm diameter is optimized as the best suitable geometry for use, against the in-practice 7 cm diameter geometry of same volume. An increase in efficiency of 10%–23% was observed for the 50–200 keV gamma energy range and a corresponding lower minimum detectable activity of 9%–20% could be achieved for the same.

Characterization of Mass Attenuation Coefficients as a Function of Experimental Geometry

Mass attenuation coefficients of H2O, PbO, and cellulose were determined using 59.5 keV gamma energies with CdTe and NaI (Tl) detectors at five different source-sample distances. The pencil beam method was used to measure the mass attenuation coefficients. All experimental mass attenuation coefficients were compared with simulated results. A linear relationship between source-sample distance and mass attenuation coefficients was determined by regression analysis. The correlation coefficients were 0.99, 0.96, and 0.98 for cellulose, H2O, and PbO using a NaI (Tl) detector, while the values were 0.98, 0.99, and 0.99 with the Cd(Te) detector. If the beams were emitted as a narrow beam instead of as a pencil beam, a constant relationship instead of a linear increase was observed for the mass attenuation coefficients as a function of distance. Consequently, the narrow beam method was superior to the pencil beam approach.

Isparta' da Çıkarılan Andezit Ve Bazalt Kayaçlarının Radyasyon Soğurma Özelliklerinin İncelenmesi

Natural stones are generally igneous, metamorphic and sedimentary are divided into 3 classes including. A region of Isparta volcanic magmatic origin andesite and basalt stones which are classified as an area where there are plenty of rocks. These rocks are used as coating materials, especially in buildings. Therefore it is important to determine stones radiation absorbing properties. In this study, in Isparta andesite and basalt rocks extracted 137Cs and 60Co radiation absorbing properties obtained from the radioactive source 662, 1173, and 1332 keV gamma energy was measured for. Gamma Spectroscopy Laboratory measurements of Suleyman Demirel University, located in the 3 x3 size NaI (Tl) detector containing gamma spectroscopy was performed using the system

DISTRIBUTION OF URANIUM IN WATER OF GRESIK COASTAL WATERS

Determination of uranium in water sample at Gresik coastal waters around Gresik industrial area have been carrid out. The purpose of research is to find the distribution of uranium at the coastal where the phosphate industry standing and potencially to contribute uranium pollutant to the waters. The measurement of uranium was pasive of Gamma Spectrometry, and uranium was measured as 234Th (uranium daughters) on 92.80 and 1001.03 keV gamma energies. Sea water sample was taken up by water pump sampler as a vertical mixing. The sample was sampling on the highest tide and lowest ebb, at the east season (March-August) west season (September-February). The concentration of 238U on higher tide of the west season are range between 0.0016-0.0128 Bq/l, while on lowest ebb of the east season are 0,0013-0,0877 Bq/l. There was significantly different (α= 5%) of uranium concentration in water between two seasons (east and west) in tide and ebb respectively. According to Quality Standard from Dirjen BATAN No.293/Dj/VII/1995 (radioactivity on environment), the concentration of 238U in water obtained from coastal around phosphate industry are still lower than that of recomended values (10.000 Bq/l). Keywords: uranium, sea water, coastal of Gresik

The influence of dead layer thickness increase on efficiency decrease for a coaxial HPGe p-type detector

The present work aims at studying the decrease in an HPGe p-type detector efficiency over its operation period and the influence of the dead layer thickness increase on this efficiency decreasing process. The study was conducted with the Canberra coaxial GC1518 p-type detector using MCNP5 code. It is found that the efficiency of this detector has reduced by 18.5% over its 13 years of operation, corresponding to the increase of dead layer thickness from 0.35 to 1.46mm. The relative reduction in efficiency linearly depends on the dead layer thickness and both these parameters are linearly grown versus operation time. The increase of the dead layer thickness causes two effects influencing the decrease in efficiency. They are the additional shielding effect of increase in dead layer thickness (shielding effect) and the effect of decrease in germanium active volume (volume effect). It is found that for 59keV gamma energy, the efficiency decrease is determined only by the shielding effect whilst the volume effect can be negligible. As for 511–1332keV gamma energies, the efficiency decrease is determined by both the volume and the shielding effects.

Estimation of 235U concentration in some depleted uranium samples by high resolution gamma-ray spectrometry using 185 keV and 1001 keV gamma-energies of 235U and 234mPa

The identification of isotopic composition of depleted uranium obtained after the reprocessing of spent fuel is very much important as far as their further applications are concerned. The concentration of 235U in the reprocessed uranium will be lower and their depletion depends mainly on the type of the reactor and burn up. The depleted uranium has a variety of applications in nuclear fuel cycle operations and industries warranting quick assessment of its isotopic composition. This paper describes the methodology developed and used for the estimation of 235U concentration in reprocessed uranium in the form of uranyl nitrate solution. A non destructive technique by high resolution gamma-ray spectrometry with HPGe detector has been used for the analysis. The activity ratio of 238U/235U, obtained from the absolute activity measurement on the 185 keV gamma-line of 235U and 1001 keV gamma-line of 234mPa, has been used for the estimation of 235U isotopic content in the sample using a mathematical formula. This method offers rapid and reliable estimate of the 235U concentration in samples comparable with that of mass spectrometry measurements. The results show that 235U concentration in the sample can be determined within 5% error for 10000 seconds counting.

Radiation transmission of concrete including boron waste for 59.54 and 80.99 keV gamma rays

Accurate measurement have been made to determine radiation transmission of boron compounds by using an extremely narrow collimated beam transmission method for 59.54 and 80.99 keV gamma energy with a Si(Li) detector. Appreciable variations were observed in the transmission factors of the concrete samples including different boron wastes (borogypsum and colemanite concentrator waste). Additionally, mass attenuation coefficients were also calculated. It is seen that μ/ ρ is increased with increasing boron concentration in the concrete and the both kind of boron waste have nearly the same property in the radiation transmission.

Determination of Iodine-131 at Low Levels in Milk: Collaborative Study

The official method for the determination of iodine-131 in milk has a lower limit of detection (LLD) of 10 pCi/L (0.37 Bq/L). The Nuclear Regulatory Commission had recommended that a method claiming to have an LLD of <0.3 pCi/L (<1.1E-02 Bq/L) be used. That method, which is capable of measuring iodine-131 below the level of detection of the Official Method, was collaboratively studied. The method uses a palladium iodide precipitate to concentrate the iodine-131 and measures (counts) its 364 keV gamma energy in coincidence with the beta decay or with a low-background beta-counting system. The study was performed by using 3 concentrations of iodine-131 in milk: 2.6, 5.0, and 8.0 pCi/L (9.62E-02, 1.85E-01, and 2.96E-01 Bq/L, respectively). Eleven laboratories agreed to participate in the study. Eight laboratories submitted data for the study. The averages of the results were 2.68, 5.30, and 8.12 pCi/L (9.92E-02, 1.96E-01, and 3.00E-01 Bq/L, respectively), respectively. The intra- and interlaboratory variations were acceptable. The method was adopted First Action by AOAC INTERNATIONAL.

Determination of Protein Levels in Nigerian Grains Using 14 MeV Neutron Activation Analysis

Abstract Fast (14 MeV) neutrons have been successfully used in investigating the protein content of different food grains (Soya Beans, Sorghum, Maize and Beans) locally grown and consumed in Nigeria. Protein was estimated via nitrogen using the 14N(n, 2n)13N reaction. Quantification of nitrogen was achieved through a γ-γ coincidence counting of 511 keV positron emissions from the decaying 13N. The implication of the use of the emitted annihilation positrons, the interference introduced in the analytical energy spectra from other activated target nuclides present in the sample, as well as possible proton “knock on” reactions anticipated from cellulose in grain matrix were assessed, and their contributions to the 511 keV gamma energy resolved. For comparative purposes, replicates of samples analyzed through Fast Neutron Activation Analysis (FNAA) were investigated using the Kjeldahl method. The samples were carried through the Kjeldahl process of pre-digestion (with appropriate catalysts), digestion and titration. The results obtained through the Kjeldahl process were found to be in good agreement with those obtained using FNAA although slightly lower. Protein content (%) of Nigerian grains analyzed varied from a low 8.75 ± 2.96 for sorghum to 35.93 ± 0.31 for soya beans.

YAP multi-crystal gamma camera prototype

The Anger camera principle has shown a practical limit of a few millimeters spatial resolution. To overcome this limit, a new gamma camera prototype has been developed, based on a position-sensitive photomultiplier tube (PSPMT) coupled with a new scintillation crystal. The Hamamatsu R2486 PSPMT is a 76-mm diameter photomultiplier tube in which the electrons produced in the conventional bi-alkali photocathode are multiplied by proximity mesh dynodes and form a charge cloud around the original coordinates of the light photon striking the photocathode. A crossed wire anode array collects the charge and detects the original position. The intrinsic spatial resolution of PSPMT is better than 0.3 mm. The scintillation crystal consists of yttrium aluminum perovskit (YAP:Ce or YAlO/sub 3/:Ce). This crystal has a light efficiency of about 38% relative to NaI, no hygroscopicity and a good gamma radiation absorption. To match the characteristics of the PSPMT, a special crystal assembly was produced by the Preciosa Company, consisting of a bundle of YAP:Ce pillars where single crystals have 0.6/spl times/0.6 mm/sup 2/ cross section and 3 mm to 18 mm length. Preliminary results from such gamma camera prototypes show spatial resolution values ranging between 0.7 mm and 1 mm with an intrinsic detection efficiency of 37/spl divide/65% for 140 keV gamma energy.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Precision measurements of standard gamma-ray energies

Several useful secondary standard gamma-ray energies have been measured with a high-resolution Ge(Li) detector. By intercomparing close-lying full-energy peaks and pair-escape peaks, precise energy values are determined. The resulting values in keV and based on the annihilation gamma energy 511.003±0.005 keV and standard gamma energies of 182Ta, 192Ir, 198Au and 137Cs are as follows: 141 Ce−145.41±0.03; 51 Cr−320.11±0.03; 69 Zn m −438.70±0.10; 60 Co−1173.25±0.08; 22 Na−1274.58±0.10; 41 Ar−1293.76±0.14; 60 Co−1332.56±0.05; 52 V−1434.19±0.05; 124 Sb−1691.24±0.08; 28 Al−1778.70±0.17; 88 Y−1836.17±0.12 .