[en] Here, a new technique for the determination of dissolved He isotope ratios in ground-waters is presented. This method is based on the extraction and subsequent equilibrium of dissolved gases in an added 'host' gas phase. Ultra pure N₂ is placed in glass flasks (250 cc), containing water samples, that were hermetically sealed after their collection. After shaking in an ultrasonic bath for 10 min, an aliquot of the separated gas phase was removed from the flask for MS analysis. ³He/⁴He ratios are measured by using a modified double collector mass spectrometer (VG 5400-TFT). Helium and Ne concentrations are calculated by comparing the partial pressures of masses 4 and 20 of the samples with those of the air-standard measured by a quadrupole mass spectrometer (QMS;VG Quartz). Using He and Ne equilibrium partitioning coefficients, it is possible to calculate the amount of gas originally dissolved in the water. The technique was tested on both air-saturated waters (ASW) and thermal waters from Stromboli (Aeolian Islands, South Italy), the results of which confirmed good reproducibility (≅5%) and accuracy (≅3%) of the data. The method was then applied to three thermal water samples collected from the same volcanic area and the results compared with those of a fumarolic and a soil gas. The isotope ratios for dissolved He gave values of 4.06-4.23 Ra, which are significantly higher than those previously reported in the literature (3.0, 3.5 and 2.9 Ra) and that measured at the fumarole (3.09 Ra), suggesting a newer and higher isotopic signature for the volcanic system. The proposed method appears to be a useful tool in the determination of ³He/⁴He ratios in ground-water systems, especially when free gases are not available or are dangerous to collect

No abstract available

[en] The August, 2 2017 Decree, which standardized the health protection requirements from the presence of radioactive substances in the waters intended for human consumption, provides for the obligation to verify the value of two parameters relating to the radioactivity content in drinking water: the concentration of tritium, which must be less than 850 UT (unit of tritium), and the total indicative dose, related to ingestion, which must be less than 0.1 mSv / year. Tritium atoms produced in the atmosphere, by combination with oxygen in the air, tritiated water (HTO) which, having greater molecular mass than the H2O molecule, has a shorter residence time in the atmosphere from which it tends to be removed with precipitation. The short periods of residence in the atmosphere and the short period of decay mean that the concentrations of tritium in the rains are low and almost constant, as there is a balance between the speed of formation, the removal by the rains and the total quantity of natural tritium in the environment which is ∼ 70 × 106 Ci (US Department of Energy, 2002). This means that in groundwater with a long residence time in subsoil, infiltrated before 1950 (nuclear test period), the concentration of tritium is below the analytical detection limit. In 1960, rainwater had an abnormal concentration (due to the emission into the atmosphere following nuclear tests) corresponding to an average value of 1000 UT. In the subsoil the decay of tritium produces its continuous loss which, in the absence of rainwater recharge and without the compensation of new atmospheric inputs, causes a decrease. To date, in the absence of any infiltration, this water would contain 35 UT. Given that waters with over 50 years generally have dilution factors from 10 to 20 times with tritium-free fossil water, today we expect, due to mixing, detectable UT values but lower than 4. Aquifer values greater than 9 UT would therefore be related to recent anthropogenic recharge or surface percolation factors. In the case of recharge with rain water rich in tritium, the concentration reflects the balance between the loss due to decay and the supply of rain water enriched with tritium. Based on the abundance of tritium, in the absence of sources of anthropogenic contamination it is possible to establish the average age of groundwater under the age of 50. This data is very important, because by analyzing the concentrations of tritium present in groundwater it is possible to trace the age of the aquifer and / or define if the aquifer is polluted by anthropogenic activities. ENEA's Environmental Traceability and Radiometry Laboratory is at the forefront of the analysis of radioisotopes in the environment, including low-concentration of tritium analyzes. In this regard, an activity with ARPAV of Treviso was started for the determination and evaluation of the concentrations of tritium found in groundwater samples of the area around the city of Treviso.

[en] In this work a novel synchronisation scheme for chaotic systems is presented. Taking inspiration from the system decomposition approach, the master and slave are connected via a switch which allows to alternate the signal fed into the slave between the master signal and the slave signal itself. The switching frequency has been taken into account as a control parameter to characterise the synchronisation properties of the system. Experimental results, performed on real Chua's circuits, confirm the validity of the approach, emphasising the fact that synchronisation is achieved for switching frequencies greater than a certain threshold

[en] The ϒ-ray spectroscopy is the quantitative study of the ϒ spectra of and finds applications in a very large number of fields, from the astrophysics to the geochemistry. The radionuclides are instable isotopes because of an excess of nuclear energy that must be released, leading to the formation of more stable nuclides. One of the possible releasing mechanisms is the emission of gamma radiation. A spectrum is characteristic, in terms of energies and intensities, of the nuclides present and allows to determine their quantity and the nature of sample under investigation. This offers the possibility of obtaining specific information, which can be acquired only with difficulty or even not at all by other techniques. This is also true in the field of food characterization and their traceability. The traceability in the food industry has become a fundamental request for the modern society. It consists in the ability of tracing any food, feed or substance used for consumption, through all stages of production, processing and distribution. For this reason, it is essential to provide transparency and safety to consumers who are demanding high quality products, with good nutritional characteristics. In the same moment, it is also important for producers, because it ensures certification and accreditation of their products. Traceability is indeed a way for ensuring that all food products are safe. In order to achieve this goal, it is necessary to use specific experimental techniques, sometime developing innovative solutions. In this paper, an application of the ϒ spectroscopy to the food traceability is presented. The gamma-emitting radionuclides can be used as markers for establishing correlations between soil and plants. Actually, a plant cannot have a much different amount of radioisotopes and a different isotopic composition than the soil in which it grows. This can make possible to trace a product and ascertain the place where it was produced. A study of the γ characterization of some Italian bean (Phaseolus vulgaris) varieties with different geographic origins, using a portable AMETEK ORTEC High Purity Germanium (HPGe) Radiation Detector, is presented. Beans are suitable for this study because they are rich in potassium, which exists in nature with a relatively high abundance of its radioactive isotope 40K. Its content in different parts of the plant, such as seeds, pods, leaves, has been measured, along with the presence of other radioisotopes. This has also allowed us to establish correlations between this element and macro elements, such as carbon and nitrogen, measured by elementary combustion. It was possible to verify the relationship between the concentration in the seeds and in the soil. Attention was also paid to the content of other radioisotopes, especially those of alkaline metals such as cesium. Due to their chemical nature, they can mimic the biological behavior of potassium and be absorbed. This may suggest further use of the cultivation of beans or leguminous plants as a possible method of bioremediation for polluted soils, because they can accumulate some specific contaminants. In principle it is also possible to recognize radioactivity arising from natural and anthropogenic origin in the soil.

[en] Studies on food traceability are of great importance nowadays, involving high demanding processes to cover all food chain steps. Extra virgin olive oil is a typical product that has a strong linkage with the Mediterranean area, and its origin protection is continuously improved both by European Regulations about its quality policy and by the development of analytical techniques increasingly appropriate. Simultaneous multi-element approach like Inductive Coupled Plasma Mass Spectrometry (ICP-MS) makes possible the representation of EVO oil’s mineral composition. Involving a ICP-MS Triple Quadrupoles (ICP-MS-QQQ) it becomes even more a powerful tool for interference-free quantitative analysis of trace and ultra-trace elements. This study aims at elaborating a method to better determine mineral composition of this matrix and at validating the method used to determine its reliability. EVO oil’s fingerprint shows its predominant elements and it points out its possible contamination with toxic elements.

[en] An automatic sensor validation strategy for the five-channel DCN (Deuterium-Carbon-Nitrogen) interferometer installed at ENEA-FTU (Frascati) is presented. The approach proposed is based on a neural model of the observed system, i.e. a model able to emulate the behaviour of a fault-free sensor and on a two-stage fuzzy system able to detect the occurrence of a fault by using a set of suitable indicators. The validation strategy has been implemented and embedded in an interactive software tool installed at FTU

[en] Photoconductivity as a function of the temperature and light intensity is studied in amorphous silicon films produced in a capacitively coupled glow discharge from a SiCl₄-H₂ gaseous mixture. The results are analysed by a simple kinetic model which takes into account two Shockley-Read imperfections in addition to the extended electron and hole states in amorphous silicon. (author)

[en] We present the results of AMS radiocarbon dating of human bones recovered in 'Grotta Cappuccini', a prehistoric cave in Galatone, Lecce (Southern Italy). The AMS analysis has confirmed the archaeological dating of the cave to the period between the end of the Copper Age and the early Bronze Age, and has given a fundamental contribution to the chronological definition of an important cultural aspect of the prehistory of Southern Italy

[en] Stilbene and NE213 organic scintillators are commonly used for neutron and γ-ray detection in mixed n/γ fields due to their pulse shape discrimination properties. A system for n/γ digital pulse shape discrimination (DPSD) and simultaneous pulse height analysis using a commercial 12-bit 200 MHz transient recorder is presented. The results of measurements performed on the fusion experiment FTU (Frascati Tokamak Upgrade) are described. The importance of DPSD for fusion applications and its advantages with respect to analog PSD are analyzed