LOCAL AND REGIONAL DISTRIBUTION OF POPS IN MOUNTAIN ENVIRONMENTSEVALUATION OF BURDEN AND FLUXES IN BIOTIC AND ABIOTIC MATRICES

In this work some of the main factors that influence the partition and distribution of POPs in mountain environments and the behaviour of pollutants inside a pasture environment are evidenced. The variability of contamination at a local scale has been deeply analyzed in the main study area of the Andossi plateau, giving some useful information about the dependence of contamination from seasonality, soil and meteorological features. With the findings of chapter II (which gave a good definition of the horizontal, vertical and seasonal variability of contamination at local scale) and the modeling of chapter III it is possible to integrate a set of simple data (about OM content and soil temperatures) with concentration data from few samples to obtain detailed maps of potential contamination and release in a mountain environment. By knowing the local variability with a high definition it is possible to draw realistic pictures of concentration into complex alpine environments and evaluate exposure risk for the local fauna or for the domestic animals grazing on alpine pastures. In chapter IV it is reported the first field work about the different retention potential of humic substances. OM is generally considered in POPs distribution papers as a whole indistinct component of soil and its effect is only viewed as quantitative (general direct relationship between OM content and POPs concentration), but the different retention potential of humin, humic acids and fulvic acids may change this view. Moreover the three humic substances have different behaviour in terms of mobility and general ability to distribute vertically and horizontally within the soil affecting the transport of the pollutants adsorbed. In chapters V and VI the distribution into biotic matrices has been evaluated, evidencing a strict relation between soil and vegetation contamination (taking also into account local variability due to different solar exposition) and also a good relation between POPs concentration in vegetation and milk. Seasonality of contamination and grazing location could lead to different intake of contaminants by cows and so higher or lower milk contamination. The first POPs contamination data in the Mt.Meru area (Tanzania) have been reported in chapter VII and some of the findings about regional scale distribution factors have been confirmed in an equatorial area

Predicting PCB concentrations in cow milk: validation of a fugacity model in high-mountain pasture conditions

A fugacity model reported in the literature was applied to a high - altitude pasture in the Italian Alps. The model takes into account three compartments (digestive tract, blood and fat tissues) in unsteady-state conditions using food as the contamination source. Disregarding biotransformation inside cow tissues, the predicted concentrations of 14 polychlorinated biphenyls (PCBs) in milk were in good agreement with the observed data, especially for congeners known for their resistance to biotransformation (e.g., CB-138 and 153). In contrast, the predicted concentrations were clearly overestimated for congeners with high biotransformation susceptibilities. Therefore data measured in milk and faeces were used to calculate the first-order-biotransformation rate constants in dairy cows. The PCB absorption efficiency observed for pasture conditionswas lower than that observed in the cowshed. The final version of the model included biotransformation and observed PCB absorption andwas able to predict PCB concentrations in cow milkwith mean differences between the predicted and measured data below \ub120% for most congener

Development and tests of a new prototype detector for the XAFS beamline at Elettra Synchrotron in Trieste

The XAFS beamline at Elettra Synchrotron in Trieste combines X-ray absorption spectroscopy and X-ray diffraction to provide chemically specific structural information of materials. It operates in the energy range 2.4-27 keV by using a silicon double reflection Bragg monochromator. The fluorescence measurement is performed in place of the absorption spectroscopy when the sample transparency is too low for transmission measurements or the element to study is too diluted in the sample. We report on the development and on the preliminary tests of a new prototype detector based on Silicon Drift Detectors technology and the SIRIO ultra low noise front-end ASIC. The new system will be able to reduce drastically the time needed to perform fluorescence measurements, while keeping a short dead time and maintaining an adequate energy resolution to perform spectroscopy. The custom-made silicon sensor and the electronics are designed specifically for the beamline requirements.Comment: Proceeding of the 6YRM 12th-14th Oct 2015 - L'Aquila (Italy). Accepted for publication on Journal of Physics: Conference Serie

NArCoS: The new hodoscope for neutrons and charged particles

Proper detection of neutrons and charged particles is motivated by the recent efforts to construct new facilities for radioactive ion beams (RIBs) worldwide. Detection of neutrons is an important opportunity to improve our understanding of nuclear spectroscopy and reaction dynamics, with the possibility of constraining theoretical models of the nuclear equation of state (NEoS) and investigating in-medium nuclear interactions. This topic also has important implications in the study of astrophysical objects, such as neutron stars. In this work, the state-of-the-art of Neutron Array for Correlation Studies (NArCoS), a new hodoscope for neutron and charged particles under construction in Catania (INFN), is briefly reviewed

The ASY-EOS experiment at GSI: investigating the symmetry energy at supra-saturation densities

The elliptic-flow ratio of neutrons with respect to protons in reactions of neutron rich heavy-ions systems at intermediate energies has been proposed as an observable sensitive to the strength of the symmetry term in the nuclear Equation Of State (EOS) at supra-saturation densities. The recent results obtained from the existing FOPI/LAND data for $^{197}$Au+$^{197}$Au collisions at 400 MeV/nucleon in comparison with the UrQMD model allowed a first estimate of the symmetry term of the EOS but suffer from a considerable statistical uncertainty. In order to obtain an improved data set for Au+Au collisions and to extend the study to other systems, a new experiment was carried out at the GSI laboratory by the ASY-EOS collaboration in May 2011.Comment: Talk given by P. Russotto at the 11th International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1, 2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference Series (JPCS

Recent results on the construction of a new correlator for neutrons and charged particles and for FARCOS

With the advent of new facilities for radioactive ion beams it is necessary to develop neutron detection systems integrated with charged-particle ones. The integration of the neutron signal, especially in the case of neutron-rich beams, becomes a mandatory requirement in order to study the property of the nuclear matter in extreme conditions. For this reason, new detectors using new materials have to be built. NArCoS (Neutron ARray for COrrelation Studies) is a project aimed at the design of a new detector based on stack of plastic scintillators, featuring both good energy and angular resolution sensitive both to neutrons and charged particles within the same detection cell. We present in this work new results on the Pulse Shape Discrimination (PSD) capabilities of two very compact detection systems: the 3 x 3 x 3 cm(3) EJ 276+SiPM and the 3 x 3 x 3 cm(3) EJ 276G +SiPM (the latter green shifted version). In addition, we compare new results about the energy calibration and resolution of the FARCOS correlator in the CHIFAR experiment performed at LNS

Multifragmentation threshold in ^{93}Nb+{nat}Mg collisions at 30 MeV/nucleon

We analyzed the $^{93}Nb$ on $^{nat}Mg$ reaction at 30 MeV/nucleon in the aim of disentangling binary sequential decay and multifragmentation decay close to the energy threshold, i.e. $\simeq 3$ MeV/nucleon. Using the backtracing technique applied to the statistical models GEMINI and SMM we reconstruct simulated charge, mass and excitation energy distributions and compare them to the experimental ones. We show that data are better described by SMM than by GEMINI in agreement with the fact that multifragmentation is responsible for fragment production at excitation energies around 3 MeV/nucleon.Comment: 16 pages, 12 figures, 5 tables Soumis \`a Nuclear Physics

Projected Quasi-particle Perturbation theory

The BCS and/or HFB theories are extended by treating the effect of four quasi-particle states perturbatively. The approach is tested on the pairing hamiltonian, showing that it combines the advantage of standard perturbation theory valid at low pairing strength and of non-perturbative approaches breaking particle number valid at higher pairing strength. Including the restoration of particle number, further improves the description of pairing correlation. In the presented test, the agreement between the exact solution and the combined perturbative + projection is almost perfect. The proposed method scales friendly when the number of particles increases and provides a simple alternative to other more complicated approaches

Isotope correlations as a probe for freeze-out characterization: central 124Sn+64Ni, 112Sn+58Ni collisions

124Sn+64Ni and 112Sn+58Ni reactions at 35 AMeV incident energy were studied with the forward part of CHIMERA multi-detector. The most central collisions were selected by means of a multidimensional analysis. The characteristics of the source formed in the central collisions, as size, temperature and volume, were inspected. The measured isotopes of light fragments (3 <= Z <=8) were used to examine isotope yield ratios that provide information on the free neutron to proton densities.Comment: 4 pages, Contribution to 8th International Conference on Nucleus-Nucleus Collisions, Moscow 200