Improved sensitivity of H.E.S.S.-II through the fifth telescope focus system

The Imaging Atmospheric Cherenkov Telescope (IACT) works by imaging the very short flash of Cherenkov radiation generated by the cascade of relativistic charged particles produced when a TeV gamma ray strikes the atmosphere. This energetic air shower is initiated at an altitude of 10-30 km depending on the energy and the arrival direction of the primary gamma ray. Whether the best image of the shower is obtained by focusing the telescope at infinity and measuring the Cherenkov photon angles or focusing on the central region of the shower is a not obvious question. This is particularly true for large size IACT for which the depth of the field is much smaller. We address this issue in particular with the fifth telescope (CT5) of the High Energy Stereoscopic System (H.E.S.S.); a 28 m dish large size telescope recently entered in operation and sensitive to an energy threshold of tens of GeVs. CT5 is equipped with a focus system, its working principle and the expected effect of focusing depth on the telescope sensitivity at low energies (50-200 GeV) is discussed.Comment: In Proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), Rio de Janeiro (Brazil

NaNet: a Low-Latency, Real-Time, Multi-Standard Network Interface Card with GPUDirect Features

While the GPGPU paradigm is widely recognized as an effective approach to high performance computing, its adoption in low-latency, real-time systems is still in its early stages. Although GPUs typically show deterministic behaviour in terms of latency in executing computational kernels as soon as data is available in their internal memories, assessment of real-time features of a standard GPGPU system needs careful characterization of all subsystems along data stream path. The networking subsystem results in being the most critical one in terms of absolute value and fluctuations of its response latency. Our envisioned solution to this issue is NaNet, a FPGA-based PCIe Network Interface Card (NIC) design featuring a configurable and extensible set of network channels with direct access through GPUDirect to NVIDIA Fermi/Kepler GPU memories. NaNet design currently supports both standard - GbE (1000BASE-T) and 10GbE (10Base-R) - and custom - 34~Gbps APElink and 2.5~Gbps deterministic latency KM3link - channels, but its modularity allows for a straightforward inclusion of other link technologies. To avoid host OS intervention on data stream and remove a possible source of jitter, the design includes a network/transport layer offload module with cycle-accurate, upper-bound latency, supporting UDP, KM3link Time Division Multiplexing and APElink protocols. After NaNet architecture description and its latency/bandwidth characterization for all supported links, two real world use cases will be presented: the GPU-based low level trigger for the RICH detector in the NA62 experiment at CERN and the on-/off-shore data link for KM3 underwater neutrino telescope

A prototype large-angle photon veto detector for the P326 experiment at CERN

The P326 experiment at the CERN SPS has been proposed with the purpose of measuring the branching ratio for the decay K^+ \to \pi^+ \nu \bar{\nu} to within 10%. The photon veto system must provide a rejection factor of 10^8 for \pi^0 decays. We have explored two designs for the large-angle veto detectors, one based on scintillating tiles and the other using scintillating fibers. We have constructed a prototype module based on the fiber solution and evaluated its performance using low-energy electron beams from the Frascati Beam-Test Facility. For comparison, we have also tested a tile prototype constructed for the CKM experiment, as well as lead-glass modules from the OPAL electromagnetic barrel calorimeter. We present results on the linearity, energy resolution, and time resolution obtained with the fiber prototype, and compare the detection efficiency for electrons obtained with all three instruments.Comment: 8 pages, 9 figures, 2 tables. Presented at the 2007 IEEE Nuclear Science Symposium, Honolulu HI, USA, 28 October - 3 November 200

An Electrically Conductive Oleogel Paste for Edible Electronics

Edible electronics will facilitate point-of-care testing through safe devices digested/degraded in the body/environment after performing a specific function. This technology, to thrive, requires a library of materials that are the basic building blocks for eatable platforms. Edible electrical conductors fabricated with green methods and at a large scale and composed of food derivatives, ingestible in large amounts without risk for human health are needed. Here, conductive pastes made with materials with a high tolerable upper intake limit (≥mg kg−1 body weight per day) are proposed. Conductive oleogel composites, made with biodegradable and food-grade materials like natural waxes, oils, and activated carbon conductive fillers, are presented. The proposed pastes are compatible with manufacturing processes such as direct ink writing and thus are suitable for an industrial scale-up. These conductors are built without using solvents and with tunable electromechanical features and adhesion depending on the composition. They have antibacterial and hydrophobic properties so that they can be used in contact with food preventing contamination and preserving its organoleptic properties. As a proof-of-principle application, the edible conductive pastes are demonstrated to be effective edible contacts for food impedance analysis, to be integrated, for example, in smart fruit labels for ripening monitoring

Crashworthiness of a composite bladder fuel tank for a tilt rotor aircraft

The fulfilment of the crash is a demanding requirement for a Tiltrotor. Indeed, such a kind of aircraft, being a hybrid between an airplane and a helicopter, inherits the requirements mainly from helicopters (EASA CS 29) due to its hovering ability. In particular, the fuel storage system must be designed in such a manner that it is crash resistant, under prescribed airworthiness requirements, in order to avoid the fuel leakage during such an event, preventing fire and, thus, increasing the survival chances of the crew and the passengers. The present work deals with the evaluation of crashworthiness of the fuel storage system of a Tiltrotor (bladder tank), and, in particular, it aims at describing the adopted numerical approach and some specific results. Crash resistance requirements are considered from the earliest design stages, and for this reason they are mainly addressed from a numerical point of view and by simulations that treat both single components and small/medium size assemblies. The developed numerical models include all the main parts needed for simulating the structural behavior of the investigated wing section: the tank, the structural components of the wing, the fuel sub-systems (fuel lines, probes, etc.) and the fuel itself. During the crash event there are several parts inside the tanks that can come into contact with the tank structure; therefore, it is necessary to evaluate which of these parts can be a damage source for the tank itself and could generate fuel loss. The SPH approach has been adopted to discretise fuel and to estimate the interaction forces with respect to the tank structure. Experimental data were used to calibrate the fuel tank and foam material models and to define the acceleration time-history to be applied. Thanks to the optimized foam’s configuration, the amount of dissipated impact energy is remarkable, and the evaluation of tanks/fuel system stress distribution allows estimating any undesired failure due to a survivable crash event

Surface acoustic wave-based lab-on-a-chip for the fast detection of Legionella pneumophila in water

Surface acoustic wave (SAW) -based immuno-biosensors are used for several applications, thanks to their versatility and faster response than conventional analytical methods. SAW immuno-biosensors can be usefully applied to promptly detect bacteria and prevent bacterial infections that can lead to severe diseases. Here, we present a SAW immuno-biosensor to detect Legionella pneumophila in water. Our device, working at ultra-high frequency (740 MHz), is functionalized with an anti-L. pneumophila antibody to maximize the specificity. We report the characteristic curve of the sensor, calculated measuring bacterial samples at known densities, and its related parameters. We also measure L. pneumophila samples contaminated with different Gram-positive and Gram-negative bacterial species (Escherichia coli and Enterococcus faecium) and samples diluted in mains waters. The proposed device is able to detect L. pneumophila in the range from 1·106 to 1·108 CFU/mL, with a limit of blank of 1.22·106 CFU/mL and a limit of detection of 2.01·106 CFU/mL. The nonspecific signal due to contaminant bacteria is very limited and measurements of L. pneumophila are not affected by contamination. We obtain a good detection also in mains water, representing a realistic matrix for L. pneumophila. Our results are encouraging and pave the way to the use of fast, easy-to-use, reliable and precise sensors to prevent bacterial infections in human activities

Edible cellulose-based conductive composites for triboelectric nanogenerators and supercapacitors

Edible electronics will enable systems that can be safely ingested and degraded in the human body after completing their function, such as sensing physiological parameters or biological markers in the gastrointestinal tract, without risk of retention or need of recollection. The same systems are potentially suitable for directly tagging food, monitoring its quality, and developing edible soft actuators control and sensing abilities. Designing appropriate edible power sources is critical to turn such a vision into real opportunities. We propose electrically conductive edible composites based on ethylcellulose and activated carbon as enabling materials for energy harvesting and storage. Free-standing, phase-separated bi-layered films, insulating at the top and with low electrical resistivity (∼10 Ω cm) at the bottom, were produced with a scalable single-step process. Food additives can tune the mechanical and triboelectrical properties of the proposed edible films. We demonstrated their successful operation as electropositive elements in organic triboelectric nanogenerators (TENGs) and as electrodes in fully edible supercapacitors (SC). The TENGs showed ∼60 V peak voltage (root mean square power density ∼2.5 μW cm−2 at 5 Hz), while the SC achieved an energy density of 3.36 mW h g−1, capacity of ∼ 9 mAh g−1, and stability for more than 1000 charge-discharge cycles. These results show that the combination of ethyl cellulose and activated carbon, and the control over their mixture, allow on-demand edible devices for energy generation and storage, serving future edible and green electronics scenarios

Surface acoustic wave-based lab-on-a-chip for the fast detection of Legionella pneumophila in water

Surface acoustic wave (SAW) -based immuno-biosensors are used for several applications, thanks to their versatility and faster response than conventional analytical methods. SAW immuno-biosensors can be usefully applied to promptly detect bacteria and prevent bacterial infections that can lead to severe diseases. Here, we present a SAW immuno-biosensor to detect Legionella pneumophila in water. Our device, working at ultra-high frequency (740 MHz), is functionalized with an anti-L. pneumophila antibody to maximize the specificity. We report the characteristic curve of the sensor, calculated measuring bacterial samples at known densities, and its related parameters. We also measure L. pneumophila samples contaminated with different Gram-positive and Gram-negative bacterial species (Escherichia coli and Enterococcus faecium) and samples diluted in mains waters. The proposed device is able to detect L. pneumophila in the range from 1·106 to 1·108 CFU/mL, with a limit of blank of 1.22·106 CFU/mL and a limit of detection of 2.01·106 CFU/mL. The nonspecific signal due to contaminant bacteria is very limited and measurements of L. pneumophila are not affected by contamination. We obtain a good detection also in mains water, representing a realistic matrix for L. pneumophila. Our results are encouraging and pave the way to the use of fast, easy-to-use, reliable and precise sensors to prevent bacterial infections in human activities

GPU-based Real-time Triggering in the NA62 Experiment

Over the last few years the GPGPU (General-Purpose computing on Graphics Processing Units) paradigm represented a remarkable development in the world of computing. Computing for High-Energy Physics is no exception: several works have demonstrated the effectiveness of the integration of GPU-based systems in high level trigger of different experiments. On the other hand the use of GPUs in the low level trigger systems, characterized by stringent real-time constraints, such as tight time budget and high throughput, poses several challenges. In this paper we focus on the low level trigger in the CERN NA62 experiment, investigating the use of real-time computing on GPUs in this synchronous system. Our approach aimed at harvesting the GPU computing power to build in real-time refined physics-related trigger primitives for the RICH detector, as the the knowledge of Cerenkov rings parameters allows to build stringent conditions for data selection at trigger level. Latencies of all components of the trigger chain have been analyzed, pointing out that networking is the most critical one. To keep the latency of data transfer task under control, we devised NaNet, an FPGA-based PCIe Network Interface Card (NIC) with GPUDirect capabilities. For the processing task, we developed specific multiple ring trigger algorithms to leverage the parallel architecture of GPUs and increase the processing throughput to keep up with the high event rate. Results obtained during the first months of 2016 NA62 run are presented and discussed