In-flight calibrations of IBIS/PICsIT

PICsIT (Pixellated Imaging CaeSium Iodide Telescope) is the high energy detector of the IBIS telescope on-board the INTEGRAL satellite. It consists of 4096 independent detection units, ~0.7 cm^2 in cross-section, operating in the energy range between 175 keV and 10 MeV. The intrinsically low signal to noise ratio in the gamma-ray astronomy domain implies very long observations, lasting 10^5-10^6 s. Moreover, the image formation principle on which PICsIT works is that of coded imaging in which the entire detection plane contributes to each decoded sky pixel. For these two main reasons, the monitoring, and possible correction, of the spatial and temporal non-uniformity of pixel performances, expecially in terms of gain and energy resolution, is of paramount importance. The IBIS on-board 22Na calibration source allows the calibration of each pixel at an accuracy of <0.5% by integrating the data from a few revolutions at constant temperature. The two calibration lines, at 511 and 1275 keV, allow also the measurement and monitoring of the PICsIT energy resolution which proves to be very stable at ~19% and ~9% (FWHM) respectively, and consistent with the values expected analytical predictions checked against pre-launch tests.Comment: 5 pages, 7 figures. Accepted for publication on A&A Special Issue on First Science with INTEGRA

The GAP-TPC

Several experiments have been conducted worldwide, with the goal of observing low-energy nuclear recoils induced by WIMPs scattering off target nuclei in ultra-sensitive, low-background detectors. In the last few decades noble liquid detectors designed to search for dark matter in the form of WIMPs have been extremely successful in improving their sensitivities and setting the best limits. One of the crucial problems to be faced for the development of large size (multi ton-scale) liquid argon experiments is the lack of reliable and low background cryogenic PMTs: their intrinsic radioactivity, cost, and borderline performance at 87 K rule them out as a possible candidate for photosensors. We propose a brand new concept of liquid argon-based detector for direct dark matter search: the Geiger-mode Avalanche Photodiode Time Projection Chamber (GAP-TPC) optimized in terms of residual radioactivity of the photosensors, energy and spatial resolution, light and charge collection efficiencyComment: 7 pages, 5 figures, Accepted for publication on JINS

Classification of ductile cast iron specimens based on image analysis and support vector machine

The ductile irons discovery in 1948 gave a new lease on life to the cast iron family. In fact, these cast irons are characterized both by a high castability and by high toughness values, combining cast irons and steel good properties. The high mechanical properties (especially ductility) are mainly due to the peculiar graphite elements shape: thanks to the addition of some elements like Mg, Ca, Ce, graphite elements shape can be near to spheres (nodules) instead to lamellae as in "normal" grey cast irons. In this work, the problem of classification of ductile cast irons specimens is addressed; first the nodules present in each specimen are identified determining their morphological shapes. These characteristics are suitable used to extract global features of the specimen. Then it is outlined a procedure to train a classifier based of these properties

Fatigue crack propagation mechanisms in C70250 and CuCrZr copper alloys

A previous study concerning the characterization of CuNiSi (C70250) and CuCrZr alloys showed very interesting characteristics of toughness evaluated with tensile tests and preliminary tests on Charpy specimens. These alloys could have interesting applications such as devices used for energy production, particle physics and aerospace. These alloys are used in the ITER (International Thermonuclear Experimental Reactor) project, an international program of great interest. For this reason, it seems important to characterize the mechanical properties of these alloys. In particular, fatigue crack propagation rate (da/dn vs ΔK) measurements were performed

The discovery of hard X-ray emission in the persistent flux of the Rapid Burster

We report the first detection with INTEGRAL of persistent hard X-ray emission (20 to 100 keV) from the Rapid Burster (MXB 1730-335), and describe its full spectrum from 3 to 100 keV. The source was detected on February/March 2003 during one of its recurrent outbursts. The source was clearly detected with a high signal to noise ratio during the single pointings and is well distinguished from the neighboring source GX 354-0. The 3 - 100 keV X-ray spectrum of the persistent emission is well described by a two-component model consisting of a blackbody plus a power-law with photon index ~ 2.4. The estimated luminosity was ~ 8.5x10^{36} erg/s in the 3 - 20 keV energy band and \~ 1.3x10^{36} erg/s in the 20 - 100 keV energy range, for a distance of 8 kpc.Comment: 5 pages, 6 figures, 1 table. Accepted for publication in A&

INTEGRAL observation of 3EG J1736-2908

The possible identification by INTEGRAL of the EGRET source 3EG J1736-2908 with the active galactic nucleus GRS 1734-292 is discussed. The latter was discovered in 1990 and later identified with a Seyfert 1 galaxy. At the time of the compilation of the 3rd EGRET Catalog, it was not considered as a possible counterpart of the source 3EG J1736-2908, which remained unidentified. A detailed multiwavelength study of the EGRET error circle is presented, by including archival radio, soft- and hard-X observations, suggesting that GRS 1734-292 could be a likely counterpart of 3EG J1736-2908, even though this poses very interesting questions about the production mechanisms of gamma-rays with energies greater than 100 MeV.Comment: 6 pages, 3 figures. Accepted for publication on A&A Main Journa

INTEGRATING CLIMATE CHANGE ADAPTATION INTO SEA AN ASSESSMENT FOR SARDINIA, ITALY

Climate Change (CC) is recognized as an urgent concern, which implies negative effects on the environment, such as sea level rise, coastal erosion, fl ooding, droughts, and desertifi cation. It involves not only the environmental, but also the economic, and social sphere. The impacts of CC are addressed through two complementary strategies: mitigation and adaptation. The fi rst one operates on the reasons of CC aiming at preventing or reducing greenhouse gases emissions, while the second one focuses on the damage they can cause, aiming at minimizing it or to take advantage of opportunities that may occur. Strategic Environmental Assessment (SEA) represents a systematic and participatory decisionmaking support process, aiming at integrating environmental considerations in the elaboration of plans and programs. While SEA regards explicitly mitigation strategies, so far it still refers marginally to CC adaptation measures to be carried on when implementing spatial planning tools at the regional and local scale. The integration of SEA processes with concepts inspired to adaptation to CCs represents a powerful tool for mainstreaming the corresponding policies and strategies. In this study, we scrutinize SEA and spatial planning tools issued in Sardinia (Italy), with reference to their attitude to incorporate possible climate adaptation concerns. We are interested in proposing and applying a framework based on internationally acknowledged criteria that need to be met to properly implement climate change adaptation measures and actions in current spatial planning and SEA practices