SiPM and front-end electronics development for Cherenkov light detection

The Italian Institute of Nuclear Physics (INFN) is involved in the development of a demonstrator for a SiPM-based camera for the Cherenkov Telescope Array (CTA) experiment, with a pixel size of 6$\times$6 mm$^2$. The camera houses about two thousands electronics channels and is both light and compact. In this framework, a R&D program for the development of SiPMs suitable for Cherenkov light detection (so called NUV SiPMs) is ongoing. Different photosensors have been produced at Fondazione Bruno Kessler (FBK), with different micro-cell dimensions and fill factors, in different geometrical arrangements. At the same time, INFN is developing front-end electronics based on the waveform sampling technique optimized for the new NUV SiPM. Measurements on 1$\times$1 mm$^2$, 3$\times$3 mm$^2$, and 6$\times$6 mm$^2$ NUV SiPMs coupled to the front-end electronics are presentedComment: In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.0589

Tracing groundwater salinization processes in coastal aquifers: a hydrogeochemical and isotopic approach in Na-Cl brackish waters of north-western Sardinia, Italy

Abstract. Throughout the Mediterranean, salinization threatens water quality, especially in coastal areas. This salinization is the result of concomitant processes related to both seawater intrusion and water–rock interaction, which in some cases are virtually indistinguishable. In the Nurra region of northwestern Sardinia, recent salinization related to marine water intrusion has been caused by aquifer exploitation. However, the geology of this region records a long history from the Palaeozoic to the Quaternary, and is structurally complex and comprises a wide variety of lithologies, including Triassic evaporites. Determining the origin of the saline component of the Jurassic and Triassic aquifers in the Nurra region may provide a useful and more general model for salinization processes in the Mediterranean area, where the occurrence of evaporitic rocks in coastal aquifers is a common feature. In addition, due to intensive human activity and recent climatic change, the Nurra has become vulnerable to desertification and, in common with other Mediterranean islands, surface water resources periodically suffer from severe shortages. With this in mind, we report new data regarding brackish and surface waters (outcrop and lake samples) of the Na-Cl type from the Nurra region, including major ions and selected trace elements (B, Br, I, and Sr), in addition to isotopic data including δ18O, δD in water, and δ34S and δ18O in dissolved SO4. To identify the origin of the salinity more precisely, we also analysed the mineralogical and isotopic composition of Triassic evaporites. The brackish waters have Cl contents of up to 2025 mg L−1 , and the ratios between dissolved ions and Cl, with the exception of the Br / Cl ratio, are not those expected on the basis of simple mixing between rainwater and seawater. The δ18O and δD data indicate that most of the waters fall between the regional meteoric water line and the global meteoric water line, supporting the conclusion that they are meteoric in origin. A significant consequence of the meteoric origin of the Na-Cl-type water studied here is that the Br / Cl ratio, extensively used to assess the origin of salinity in fresh water, should be used with care in carbonate aquifers that are near the coast. Overall, δ34S and δ18O levels in dissolved SO4 suggest that water–rock interaction is responsible for the Na-Cl brackish composition of the water hosted by the Jurassic and Triassic aquifers of the Nurra, and this is consistent with the geology and lithological features of the study area. Evaporite dissolution may also explain the high Cl content, as halite was detected within the gypsum deposits. Finally, these Na-Cl brackish waters are undersaturated with respect to the more soluble salts, implying that in a climate evolving toward semi-arid conditions, the salinization process could intensify dramatically in the near future

Economics of One Health: Costs and benefits of integrated West Nile virus surveillance in Emilia-Romagna

Since 2013 in Emilia-Romagna, Italy, surveillance information generated in the public health and in the animal health sectors has been shared and used to guide public health interventions to mitigate the risk of West Nile virus (WNV) transmission via blood transfusion. The objective of the current study was to identify and estimate the costs and benefits associated with this One Health surveillance approach, and to compare it to an approach that does not integrate animal health information in blood donations safety policy (uni-sectoral scenario). Costs of human, animal, and entomological surveillance, sharing of information, and triggered interventions were estimated. Benefits were quantified as the averted costs of potential human cases of WNV neuroinvasive disease associated to infected blood transfusion. In the 2009–2015 period, the One Health approach was estimated to represent a cost saving of €160,921 compared to the uni-sectoral scenario. Blood donation screening was the main cost for both scenarios. The One Health approach further allowed savings of €1.21 million in terms of avoided tests on blood units. Benefits of the One Health approach due to short-term costs of hospitalization and compensation for transfusion-associated disease potentially avoided, were estimated to range from €0 to €2.98 million according to the probability of developing WNV neuroinvasive disease after receiving an infected blood transfusion

Exponentially-fitted Gauss-Laguerre quadrature rule for integrals over an unbounded interval

New quadrature formulae are introduced for the computation of integrals over the whole positive semiaxis when the integrand has an oscillatory behavior with decaying envelope. The new formulae are derived by exponential fitting, and they represent a generalization of the usual Gauss-Laguerre formulae. Their weights and nodes depend on the frequency of oscillation in the integrand, and thus the accuracy is massively increased. Rules with one up to six nodes are treated with details. Numerical illustrations are also presented

Stability theory of TASE-Runge-Kutta methods with inexact Jacobian

This paper analyzes the stability of the class of Time-Accurate and Highly-Stable Explicit Runge-Kutta (TASE-RK) methods, introduced in 2021 by Bassenne et al. (J. Comput. Phys.) for the numerical solution of stiff Initial Value Problems (IVPs). Such numerical methods are easy to implement and require the solution of a limited number of linear systems per step, whose coefficient matrices involve the exact Jacobian $J$ of the problem. To significantly reduce the computational cost of TASE-RK methods without altering their consistency properties, it is possible to replace $J$ with a matrix $A$ (not necessarily tied to $J$) in their formulation, for instance fixed for a certain number of consecutive steps or even constant. However, the stability properties of TASE-RK methods strongly depend on this choice, and so far have been studied assuming $A=J$. In this manuscript, we theoretically investigate the conditional and unconditional stability of TASE-RK methods by considering arbitrary $A$. To this end, we first split the Jacobian as $J=A+B$. Then, through the use of stability diagrams and their connections with the field of values, we analyze both the case in which $A$ and $B$ are simultaneously diagonalizable and not. Numerical experiments, conducted on Partial Differential Equations (PDEs) arising from applications, show the correctness and utility of the theoretical results derived in the paper, as well as the good stability and efficiency of TASE-RK methods when $A$ is suitably chosen.Comment: 26 page

Smart actuation for helicopter rotorblades

Successful rotorcrafts were only achieved when the differences between hovering flight conditions and a stable forward flight were understood. During hovering, the air speed on all helicopter blades is linearly distributed along each blade and is the same for each. However, during forward flight, the forward motion of the helicopter in the air creates an unbalance. The airspeed is increased for the blade passing in the advancing side of the helicopter, while it is reduced in the retreating side. Moreover, when each blade enters the retreating side of the helicopter, a reverse flow occurs around the profile where the blade speed is lower than the forward speed of the helicopter. The balance of a rotorcraft is solved by a cyclic pitch control, but trade-offs are made on the blade design to cope with the great variety of aerodynamic conditions. A smart blade that would adapt its characteristics to this large set of conditions would improve rotorcrafts energy efficiency while providing vibration and noise control.\ud Smart rotor blades systems are studied to adapt the aerodynamic characteristics of the blade during its revolution and to improve the overall performances. An increase in the lift over drag ratio on the retreating side has been studied to design a blade with better aerodynamic efficiency and better stall performances in the low-speed region. The maximum speed of a rotorcraft is limited by the angle of attack that the profile can sustain on the retreating side before stall. Therefore, increasing the maximum angle of attack that a profile geometry can sustain increases the rotorcraft flight envelope. Flow asymmetry and aerodynamic interaction between successive blades are also investigated to actively reduce vibrations and limit noise.\ud These improvements can be achieved by deploying flaps, by using flow control devices or by morphing the full shape of the profile at a specific places during the blade revolution. Each of the listed methods has advantages and disadvantages as well as various degrees of feasibility and integrability inside helicopter blades. They all modify the aerodynamic characteristics of the profile. Their leverage on the various aerodynamic effects depends on the control strategy chosen for actuation. Harmonic actuation is therefore studied for active noise and vibration control whereas stepped deployment is foreseen to modify the stall behaviour of the retreating side of the helicopter.\ud Helicopter blades are subjected to various force constraints such as the loads from the complex airflow and the centrifugal forces. Furthermore, any active system embedded inside a rotor blade needs to comply with the environmental constraints to which a helicopter will be subjected  during its life-span. Other concerns, like the power consumption and the data transfer for blade control, play an important role as well. Finally, such a system must have a life-time exceeding the life-time of a rotor blade and meet the same criteria in toughness, reliability and ease of maintenance.\ud Smart system is an interplay of aerodynamics, rotor-mechanics, material science and control, thus a multidisciplinary approach is essential. A large part of the work consists in building processes to integrate these domains for investigating, designing and testing smart components.\ud Piezoelectric actuators are a promising technology to bring adaptability to rotor blades. They can be used directly on the structure to actively modify its geometry, stiffness and aerodynamic behaviour or be integrated to mechanisms for the deployment of flaps. Their large specific work, toughness, reliability and small form factor make them suitable components for integration within a rotor blade. The main disadvantage of piezoelectric actuators is the small displacement and strain available. Amplification mechanisms must be optimised to produce sufficient displacement in morphing applications.\ud Smart actuation systems placed inside rotor blades have the potential to improve the efficiency and the performances of tomorrow's helicopters. Piezoelectric materials can address many of the challenges of integrating smart components inside helicopter blades. The key aspect remains the collaboration between various domains, skills and expertise to successfully implement these new technologies