Ascertainment of variations in the biological half-lives of bromide and sodium ions in the rat by in vivo gamma-ray measurement of Br and Na radionuclides

With the aid of in vivo whole-body counting of the rats (administered simultaneously with the radionuclides ⁸²Br and ²⁴Na) by high-resolution gamma-ray spectrometry, we extended the applicability of our experimentally proved hypothesis that the biological half-life of bromide depends on the magnitude of sodium intake rather than on the intake of chloride, as was generally assumed. Variations in the biological half-life of bromide, as a substitute for sodium, were investigated in animals situated in very different physiological states, as regards their metabolic activity.     

Concentration of radiocaesium Cs and Cs in sediments of the Malaysian marine environment

The concentrations of ¹³⁷Cs and ¹³⁴Cs in Malaysian marine sediments were measured by gamma-ray spectrometry with a high-purity germanium (HPGe) detector connected to a multichannel analyzer. In general, the ¹³⁷Cs concentration in Malaysian marine sediments has been found to be very low and less than 5 Bq/kg dry weight with the exception of those from a few sampling locations. The concentration of ¹³⁴Cs was found to be less than the minimum detectable activity for the measuring condition used. Data reported in this paper were found to be comparable with results from within the region and thus can be used as reference data for the country.     

Coincidence summing corrections for volume samples using the PENELOPE/penEasy Monte Carlo code

The coincidence summing correction factors estimated with penEasy, a steering program for the Monte Carlo simulation code PENELOPE, and with penEasy-eXtended, an in-house modified version of penEasy, are presented and discussed for ¹⁵²Eu and ¹³⁴Cs in volume sources. The geometries and experimental data were obtained from an intercomparison study organized by the International Committee for Radionuclide Metrology (ICRM). A significant improvement in the results calculated with PENELOPE/penEasy was obtained when X-rays are included in the ¹⁵²Eu simulations.     

Monte Carlo simulation of the self-absorption corrections for natural samples in gamma-ray spectrometry

Gamma-ray self-attenuation corrections in the energy range 60–2000 keV were evaluated by means of Monte Carlo calculations for environmental samples in a cylindrical measuring geometry. The dependence of the full-energy peak efficiency on the sample density was obtained for some particular photon energies and, as a result, the corresponding self-attenuation correction factors were obtained. The calculations were performed by assuming that natural materials have mass attenuation coefficients very similar to those of water in the energy range studied. Three different HpGe coaxial detectors were considered: an n-type detector with 44.3% relative efficiency and two p-type detectors of relative efficiencies 20.0% and 30.5%. Our calculations were in very good agreement with the self-attenuation correction factors obtained experimentally by other workers for environmental samples of different densities. This work demonstrates the reliability of Monte Carlo calculations for correcting photon self-attenuation in natural samples. The results also show that the corresponding correction factors are essentially unaffected by the specific coaxial detector used.     

Uncertainty evaluation in radon concentration measurement using charcoal canister

Active charcoal detectors are used for testing the concentration of radon in dwellings. The method of measurement is based on radon adsorption on coal and measurement of gamma radiation of radon daughters. The contributions to the final measurement uncertainty are identified, based on the equation for radon activity concentration calculation. Different methods for setting the region of interest for gamma spectrometry of canisters were discussed and evaluated. The obtained radon activity concentration and uncertainties do not depend on peak area determination method.     

伽马射线体外照射对细粒棘球蚴原头节的杀灭作用

目的 探讨细粒棘球蚴原头节体外照射γ-射线后导致的死亡、细胞内caspase-3的表达和显微结构的变化。方法 在体外培养的基础上,用不同剂量的γ-射线对细粒棘球蚴原头节进行照射。对照射后各组原头节细胞内的caspase-3蛋白酶活性进行测定,观察期原头节死亡率,并在倒置显微镜下动态观察原头节形态结构的变化。结果 原头节经过γ-射线体外照射后会出现死亡率升高,caspase-3表达增强现象,同时原头节形态结构出现肿胀、塌陷、碎裂的阶段性变化。结论 γ-射线体外照射可以直接杀灭原头节,且诱导原头节细胞发生凋亡。     

Gamma-ray spectrometry method used for radioactive waste drums characterization for final disposal at National Repository for Low and Intermediate Radioactive Waste – Baita,Romania

The Radioactive Waste Management Department from IFIN-HH, Bucharest, performs the conditioning of the institutional radioactive waste in concrete matrix, in 200 l drums with concrete shield, for final disposal at DNDR – Baita, Bihor county, in an old exhausted uranium mine. This paper presents a gamma-ray spectrometry method for the characterization of the radioactive waste drums' radionuclides content, for final disposal. In order to study the accuracy of the method, a similar concrete matrix with Portland cement in a 200 l drum was used.     

Multivariate statistical analysis of radiological data of building materials used in Tiruvannamalai,Tamilnadu, India

Using γ spectrometry, the concentration of the naturally occurring radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K has been measured in soil, sand, cement, clay and bricks, which are used as building materials in Tiruvannamalai, Tamilnadu, India. The radium equivalent activity (Ra_eq), the criterion formula (CF), indoor gamma absorbed dose rate (D_R), annual effective dose (H_R), activity utilization index (AUI), alpha index (I_α), gamma index (I_γ), external radiation hazard index (H_ex), internal radiation hazard index (H_in), representative level index (RLI), excess lifetime cancer risk (ELCR) and annual gonadal dose equivalent (AGDE) associated with the natural radionuclides are calculated to assess the radiation hazard of the natural radioactivity in the building materials. From the analysis, it is found that these materials used for the construction of dwellings are safe for the inhabitants.The radiological data were processed using multivariate statistical methods to determine the similarities and correlation among the various samples. The frequency distributions for all radionuclides were analyzed. The data set consisted of 15 measured variables. The Pearson correlation coefficient reveals that the ²²⁶Ra distribution in building materials is controlled by the variation of the ⁴⁰K concentration. Principal component analysis (PCA) yields a two-component representation of the acquired data from the building materials in Tiruvannamalai, wherein 94.9% of the total variance is explained. The resulting dendrogram of hierarchical cluster analysis (HCA) classified the 30 building materials into four major groups using 15 variables.     

Design and study of a coplanar grid array CdZnTe detector for improved spatial resolution

Coplanar grid (CPG) CdZnTe detectors have been used as gamma-ray spectrometers for years. Comparing with pixelated CdZnTe detectors, CPG CdZnTe detectors have either no or poor spatial resolution, which directly limits its use in imaging applications. To address the issue, a 2×2 CPG array CdZnTe detector with dimensions of 7×7×5 mm³ was fabricated. Each of the CPG pairs in the detector was moderately shrunk in size and precisely designed to improve the spatial resolution while maintaining good energy resolution, considering the charge loss at the surface between the strips of each CPG pairs. Preliminary measurements were demonstrated at an energy resolution of 2.7–3.9% for the four CPG pairs using 662 keV gamma rays and with a spatial resolution of 3.3 mm, which is the best spatial resolution ever achieved for CPG CdZnTe detectors. The results reveal that the CPG CdZnTe detector can also be applied to imaging applications at a substantially higher spatial resolution.