A survey was carried out to determine activity concentration levels and associated dose rates from the naturally occurring radionuclides 232Th, 238U and 40K, in the various geological formations of ...Cyprus, by means of high-resolution gamma ray spectrometry. A total of 115 representative soil samples were collected from all over the bedrock surface of the island, based on the different lithological units of the study area, sieved through a fine mesh, sealed in 1000 ml plastic Marinelli beakers and measured in the laboratory with respect to gamma radioactivity for a counting time of 18-h each. From the measured spectra, activity concentrations were determined for 232Th (range from 1.0 × 10−2 to 39.8 Bq kg−1), 238U (from 1.0 × 10−2 to 39.3 Bq kg−1) and 40K (from 4.0 × 10−2 to 565.8 Bq kg−1). Gamma absorbed dose rates in air outdoors were calculated to be in the range from 1.1 × 10−2 to 51.3 nGy h−1, depending on the geological features, with an overall mean value of 8.7 nGy h−1 and a standard deviation of 8.4 nGy h−1. This value is by a factor of about seven below the corresponding population-weighted world-averaged value of 60 nGy h−1 and one of the lowest that has been reported from similar investigations worldwide. Assuming a 20% occupancy factor, the corresponding effective dose rates outdoors equivalent to the population were calculated to be between 1.3 × 10−2 and 62.9 µSv y−1, with an arithmetic mean value of 10.7 µSv y−1 and a standard deviation of 10.3 µSv y−1.
A first comprehensive study is presented on radioactivity concentrations and dose rates in 87 commonly used materials, manufactured or imported in Cyprus, for building purposes. The natural ...radioactivity of 40K, 232Th, 238U and 226Ra is determined using high-resolution gamma-ray spectroscopy. The respective dose rates and the associated radiological effect indices are also calculated. A comparison of the measured specific activity values with the corresponding world average values shows that most of them are below the world average activity values. The annual indoor effective dose rates received by an individual from three measured imported granites and four measured imported ceramics are found to be higher than the world upper limit value of 1 mSv y−1. Hence, these materials should have a restricted use according to their corresponding calculated activity concentration index values and the related EC 1999 guidelines.
A systematic study of the indoor airborne radon concentration in the central part of the Nicosia district was conducted, using high-sensitivity active radon portable detectors of the type “RADIM3A”. ...From a total of 108 measurements in 54 grids of 1km2 area each, the overall mean value is 20.6±13.2Bqm−3 (A.M.±S.D.). That is almost twice less than the corresponding average worldwide value. The radon concentration levels in drinking water were also measured in 24 sites of the residential district, using the high-sensitivity radon detector of the type “RADIM3W”. The mean value obtained from these measurements is 243.8±224.8mBql−1, which is relatively low compared to the corresponding internationally accepted level. The associated annual effective dose rates to each measurement were also calculated and compared to the corresponding worldwide values. From the geographical coordinates of the measuring sites and the corresponding radon concentration values, the digital radon map of the central part of the Nicosia district was constructed for the first time, by means of the ArcMap software package.
► Indoor airborne radon concentration in the central part of the Nicosia district. ► Overall mean radon concentration value is almost twice less than the corresponding average worldwide values. ► Radon concentration levels in drinking water are relatively low. ► Calculations of the associated annual effective dose rates. ► Radon map of the central part of the Nicosia district.
In situ, high-resolution, gamma-ray spectrometry of a total number of 70 outdoor and 20 indoor representative measurements were performed in preselected, common locations of the main urban areas of ...Cyprus. Specific activities and gamma absorbed dose rates in air due to the naturally occurring radionuclides of 232Th and 238U series, and 40K are determined and discussed. Effective dose rate to the Cyprus population due to terrestrial gamma radiation is derived directly from this work. The results obtained outdoors match very well with those derived previously by high-resolution gamma spectrometry of soil samples, which were collected from the main island bedrock surface. This implies that the construction and building materials in urban areas do not affect the external gamma dose rate; thus they are mostly of local origin. Finally, the indoor/outdoor gamma dose ratio was found to be 1.4 ± 0.5.
Preconcentration of uranium from natural water samples using Chelex-100 cation-exchange resin, its selective extraction by tributylphosphate and electrodeposition on stainless steel discs is ...reported. The validity of the separation procedure and the chemical recoveries were checked by addition of uranium standard solution as well as by tracing with 232U. The average uranium yield for the cation-exchange was (97±2)%, for the liquid-liquid extraction was (95±2)% and for the electrodeposition was more than 99%. Employing high-resolution a-spectroscopy, the measured activity of 238U and 234U radioisotopes was found to be ~7 mBq.l-1 and ~35 mBq.l-1 for ground- and seawater samples, respectively. The energy resolution (FWHM) of the α-peaks was 22 keV, the minimum detectable activity (MDA) was estimated to be 1 mBq.l-1 (at 95% confidence limit).
Using high-sensitivity radon (
222Rn) portable detectors (passive electronic devices of the type RADIM3), the airborne
222Rn concentration in the interior of various Cypriot buildings and dwellings ...was measured. For each preselected building and dwelling, a calibrated detector was put into a closed room, and the
222Rn concentration was registered in sampling intervals of 2 to 4 h for a total counting time of typically 48 h.
222Rn activity concentrations were found to be in the range of 6.2 to 102.8 Bq m
−3, with an overall arithmetic mean value of (19.3±14.7) Bq m
−3. This value is by a factor of two below the world average (population-weighted) value of 39 Bq m
−3. The total annual effective dose equivalent to the Cypriot population was calculated to be between 0.16 and 2.6 mSv with an overall arithmetic mean value of (0.49±0.37) mSv.
High-resolution γ-ray spectrometry was exploited to determine naturally occurring thorium (Th), uranium (U) and potassium (K) elemental concentrations in the whole area covered by the Troodos ...Ophiolite Complex of Cyprus. For that purpose, a total of 59 samples from surface soils and 10 from the main rock formations of the region of interest were analysed. Elemental concentrations were determined for Th (range from 2.5×10
−3 to 2.0 ppm), U (from 8.1×10
−4 to 0.6 ppm), and K (from 1.3×10
−4% to 1.0%). The average values (A.M±S.D.) derived are (0.24±0.34) ppm, (0.10±0.10) ppm and (0.21±0.24)%, for Th, U, and K, respectively, in the soils, and (0.52±0.17) ppm, (0.17±0.11) ppm and (0.49±0.87)% in the rocks. From these values, a radioactivity (radioelement) loss of nearly 50% is estimated in the underlying surface soils due to leaching and eluviation during weathering of the rocks. The measured Th/U ratio exhibits values between 2 and 4, whereas the K/Th ratio is highly variable ranging between 1.5×10
3 and 3.0×10
4.
A comprehensive study was conducted to determine thorium, uranium and potassium elemental concentrations in surface soils throughout the accessible area of Cyprus using high-resolution γ-ray ...spectrometry. A total of 115 soil samples was collected from all over the bedrock surface of the island based on the different lithological units of the study area. The soil samples were air-dried, sieved through a fine mesh, sealed in 1000-ml plastic Marinelli beakers, and measured in the laboratory in terms of their gamma radioactivity for a counting time of 18 h each. From the measured γ-ray spectra, elemental concentrations were determined for thorium (range from 2.5×10
−3 to 9.8 μg g
−1), uranium (from 8.1×10
−4 to 3.2 μg g
−1) and potassium (from 1.3×10
−4 to 1.9%). The arithmetic mean values (A.M.±S.D.) calculated from all samples are: (1.2±1.7) μg g
−1, (0.6±0.7) μg g
−1 and (0.4±0.3)%, for thorium, uranium and potassium, respectively, which are by a factor of three–six lower than the world average values of 7.4 μg g
−1 (Th), 2.8 μg g
−1 (U) and 1.3% (K) derived from all data available worldwide. The best-fitting relation between the concentrations of Th and K versus U and also of K versus Th, is essentially of linear type with a correlation coefficient of 0.93, 0.84 and 0.90, respectively. The Th/U, K/U and K/Th ratios (slopes) extracted are equal to 2.0, 2.8×10
3 and 1.4×10
3, respectively.
.
The centrality determination for Au + Au collisions at 1.23
A
GeV, as measured with HADES at the GSI-SIS18, is described. In order to extract collision geometry related quantities, such as the ...average impact parameter or number of participating nucleons, a Glauber Monte Carlo approach is employed. For the application of this model to collisions at this relatively low centre-of-mass energy of
s
NN
=
2
.
42
GeV special investigations were performed. As a result a well defined procedure to determine centrality classes for ongoing analyses of heavy-ion data is established.
Employing the Bonn–Gatchina partial wave analysis framework (PWA), we have analyzed HADES data of the reaction p(3.5 GeV)+p→pK+Λ. This reaction might contain information about the kaonic cluster ...“ppK−” (with quantum numbers JP=0− and total isospin I=1/2) via its decay into pΛ. Due to interference effects in our coherent description of the data, a hypothetical K‾NN (or, specifically “ppK−”) cluster signal need not necessarily show up as a pronounced feature (e.g. a peak) in an invariant mass spectrum like pΛ. Our PWA analysis includes a variety of resonant and non-resonant intermediate states and delivers a good description of our data (various angular distributions and two-hadron invariant mass spectra) without a contribution of a K‾NN cluster. At a confidence level of CLs=95% such a cluster cannot contribute more than 2–12% to the total cross section with a pK+Λ final state, which translates into a production cross-section between 0.7 μb and 4.2 μb, respectively. The range of the upper limit depends on the assumed cluster mass, width and production process.
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