G. P. Bezzon

A new FSA approach for in situ γ ray spectroscopy.

An increasing demand of environmental radioactivity monitoring comes both from the scientific community and from the society. This requires accurate, reliable and fast response preferably from portable radiation detectors. Thanks to recent improvements in the technology, γ spectroscopy with sodium iodide scintillators has been proved to be an excellent tool for in-situ measurements for the identification and quantitative determination of γ ray emitting radioisotopes, reducing time and costs. Both for geological and civil purposes not only (40)K, (238)U, and (232)Th have to be measured, but there is also a growing interest to determine the abundances of anthropic elements, like (137)Cs and (131)I, which are used to monitor the effect of nuclear accidents or other human activities. The Full Spectrum Analysis (FSA) approach has been chosen to analyze the γ spectra. The Non Negative Least Square (NNLS) and the energy calibration adjustment have been implemented in this method for the first time in order to correct the intrinsic problem related with the χ(2) minimization which could lead to artifacts and non physical results in the analysis. A new calibration procedure has been developed for the FSA method by using in situ γ spectra instead of calibration pad spectra. Finally, the new method has been validated by acquiring γ spectra with a 10.16 cm × 10.16 cm sodium iodide detector in 80 different sites in the Ombrone basin, in Tuscany. The results from the FSA method have been compared with the laboratory measurements by using HPGe detectors on soil samples collected particular, the (137)Cs isotopes has been implemented in the analysis since it has been found not negligible during the in-situ measurements.

First characterisation of natural radioactivity in building materials manufactured in Albania

This study focuses on the radiological characterisation of building materials manufactured in Albania by using a high-resolution gamma-ray spectrometer. The average activity concentrations of (40)K, (226)Ra and (232)Th were, respectively, 644.1±64.2, 33.4 ± 6.4 and 42.2 ± 7.6 Bq kg(-1) in the clay brick samples and 179.7 ± 48.9, 55.0 ± 5.8 and 17.0 ± 3.3 Bq kg(-1) in the cement samples. The calculated activity concentration index (ACI), varied from 0.48±0.02 to 0.63±0.04 in the clay brick samples and from 0.29±0.03 to 0.37±0.02 in the cement samples. Based on the ACI, all of the clay brick and cement samples were categorised as A1 materials. The authors can exclude (at 3σ level) any restriction of their use as bulk materials.

Total natural radioactivity, Tuscany, Italy

In this paper, we report an extensive survey of the natural radioactive content of rocks of the Tuscany Region (Italy): this permitted the first total natural radioactivity map of the region. The sampling was planned using the geological map of Tuscany at scale 1:250,000, which contains 45 distinct geological groups recognized by tectonic and stratigraphic features. Each geological group was characterized for the total activity by measuring the activity concentrations of 40K, 238U and 232Th in 865 samples using a high-purity germanium (HPGe) gamma-ray spectrometer. The average areal distribution of samples is approximately one sample per 25 km2. The radiometric map was constructed through the reclassification of each geological formation based on the median value of the total activity. Seven classes of total activity are identified by choosing percentiles almost evenly spread across the range of values. This map represents the starting point for future studies on natural background radiation, geochemical processes and epidemiological investigations.

Total natural radioactivity, Veneto (Italy)

We present the first detailed map of the terrestrial natural radioactivity of the Veneto Region (Italy), a 18,264 km2 densely populated area, previously investigated through indoor radon surveys. The activity concentration in 709 representative samples of the main Alpine lithostratigraphic units was measured by using a high-purity germanium (HPGe) γ-ray spectrometer to characterize the radioactivity content of the 41 cartographic units of the Veneto Lithostratigraphic map at 1:250,000 scale. An area accounting for 61% of the territory, comprising alluvial plains was investigated through airborne γ-ray measurements. The large-volume NaI detectors were mounted on an ultralight aircraft, flying a 7000 km line. The data were interpolated using Ordinary Kriging, and a distribution model of the radioactivity content was produced. The result of the data analysis is a total natural radioactivity map of Veneto at 1:250,000 scale in which the activity concentration of the territory is visualized in seven classes, according to the percentile values calculated on the total dataset of measurements.

Uranium distribution in the Variscan Basement of Northeastern Sardinia

ABSTRACT We present a detailed map of uranium distribution and its uncertainties in the Variscan Basement of Northeastern Sardinia (VBNS) at a scale of 1:100,000. An area of 2100 km2 was investigated by means of 535 data points obtained from laboratory and in situ gamma-ray spectrometry measurements. These data volume corresponds to the highest sampling density of the European Variscides, aimed at studying the genetic processes of the upper crust potentially triggered by an enrichment of radiogenic heat-producing elements. For the first time, the Kriging with Variance of Measurement Error method was used to assign weights to the input data which are based on the degree of confidence associated with the measurements obtained using different gamma-ray spectrometry techniques. A detailed tuning of the model parameters for the adopted Experimental Semi-Variogram led to the identification of a maximum distance of spatial variability coherent to the observed tendency of the experimental data. We demonstrate that the obtained uranium distribution in the VBNS, characterized by several calc-alkaline plutons emplaced within migmatitic massifs and amphibolite-facies metamorphic rocks, is an excellent benchmark for the study of ‘hot’ collisional chains. The uranium map of VBNS, and in particular the Arzachena minor pluton, confirms the emplacement model based on the recognition of the different petrological associations characterizing the Variscan magmatic processes in the Late Paleozoic. Furthermore, the presented model of the uranium content of the geological bedrock is a potential baseline for future mapping of radon-prone areas.

Mapping the natural radioactivity of Elba Island by means of geostatistical interpolation of airborne gamma-ray data.

Automated !-ray spectrometer for monitoring wastes made by nonnuclear industries XHIXHA G.1, BEZZON G.P.1, BROGGINI C.2, BUSO G.P.1, CACIOLLI A.2, CALLEGARI I.3, COLONNA T.3, FIORENTINI G.1, GUASTALDI E.3, KACELI XHIXHA M.4, MANTOVANI F.5, MASSA G.3, MENEGAZZO R.2, MOU L.1 ROSSI ALVAREZ AND C.2 AND STRATI V.5 1Legnaro National Laboratory (LNL-INFN), Via dell’Universita, 2 35020 Legnaro, Padova, Italy – (xhixha@fe.infn.it) 2Padova Section INFN, Via Marzolo 8 35131 Padova, Italy – (carlo.broggini@pd.infn.it ) 3CGT Center for GeoTechnologies, University of Siena, Via Vetri Vecchi, 34 52027 S. GiovanniValdarno, Italy – ()callegari@unisi.it 4University of Sassari, Botanical, Ecological and Geological Sciences Department, Piazza Universita 2107100 Sassari, Italy – (mxhixha@fe.infn.it ) 5University of Ferrara, Physics Department, Via Saragat, 1 44100 Ferrara, Italy – (mantovani@fe.infn.it )