F. Ameli

Università di Pisa, Pisa, Tuscany, Italy

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Publications (70)83.51 Total impact

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    ABSTRACT: The results of the analysis of the data collected with the NEMO Phase-2 tower, deployed at 3500 m depth about 80 km off-shore Capo Passero (Italy), are presented. Cherenkov photons detected with the photomultipliers tubes were used to reconstruct the tracks of atmospheric muons. Their zenith-angle distribution was measured and the results compared with Monte Carlo simulations. An evaluation of the systematic effects due to uncertainties on environmental and detector parameters is also included. The associated depth intensity relation was evaluated and compared with previous measurements and theoretical predictions. With the present analysis, the muon depth intensity relation has been measured up to 13 km of water equivalent.
    12/2014;
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    ABSTRACT: The first prototype of a photo-detection unit of the future KM3NeT neutrino telescope has been deployed in the deep waters of the Mediterranean Sea. This digital optical module has a novel design with a very large photocathode area segmented by the use of 31 three inch photomultiplier tubes. It has been integrated in the ANTARES detector for in-situ testing and validation. This paper reports on the first months of data taking and rate measurements. The analysis results highlight the capabilities of the new module design in terms of background suppression and signal recognition. The directionality of the optical module enables the recognition of multiple Cherenkov photons from the same $^{40}$K decay and the localization bioluminescent activity in the neighbourhood. The single unit can cleanly identify atmospheric muons and provide sensitivity to the muon arrival directions.
    European Physical Journal C 09/2014; 74:3056. · 5.25 Impact Factor
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    ABSTRACT: 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.
    06/2014;
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    ABSTRACT: In March 2013, the NEMO Phase 2 tower has been successfully installed in the Capo Passero site, at a depth of 3500 m and 80 km off from the southern coast of Sicily. The unfurled tower is 450 m high; it is composed of 8 mechanical floors, for a total amount of 32 PMTs and various instruments for environmental measurements. The tower positioning is achieved by an acoustic system. The tower is continuously acquiring and transmitting all the measured signals to shore. Data reduction is completely performed in the Portopalo shore station by a dedicated computing facility connected to the persistent storage system at LNS, in Catania. Results from the last 9 months of acquisition will be presented. In particular, the analyzed optical rates, showing stable and low baseline values, are compatible with the contribution mainly of 40K light emission, with a small percentage of light bursts due to bioluminescence. These features reveal the optimal nature of the Capo Passero abyssal site to host a km3 -sized Neutrino Telescope.
    Journal of Instrumentation 03/2014; 9:C03045. · 1.66 Impact Factor
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    ABSTRACT: Please see the PDF file for details.
    Journal of Instrumentation 08/2013; 8(08):E08001. · 1.66 Impact Factor
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    Journal of Instrumentation 07/2013; 8(07):P07001. · 1.66 Impact Factor
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    ABSTRACT: Detection of high-energy neutrinos from distant astrophysical sources will open a new window on the Universe. The detection principle exploits the measurement of Cherenkov light emitted by charged particles resulting from neutrino interactions in the matter containing the telescope. A novel multi-PMT digital optical module (DOM) was developed to contain 31 3-inch photomultiplier tubes (PMTs). In order to maximize the detector sensitivity, each PMT will be surrounded by an expansion cone which collects photons that would otherwise miss the photocathode. Results for various angles of incidence with respect to the PMT surface indicate an increase in collection efficiency by 30% on average for angles up to 45°� with respect to the perpendicular. Ray-tracing calculations could reproduce the measurements, allowing to estimate an increase in the overall photocathode sensitivity, integrated over all angles of incidence, by 27% (for a single PMT). Prototype DOMs, being built by the KM3NeT consortium, will be equipped with these expansion cones.
    Journal of Instrumentation 03/2013; 8(T03006). · 1.66 Impact Factor
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    ABSTRACT: The Timing Trigger and Control (TTC) system is an optical network which distributes the timing and synchronization signals of the Large Hadron Collider (LHC) machine to the LHC experiments. It is also used to transmit the trigger information of each experiment to the on-detector electronics. The TTC system has been designed in the late 90's, by using VLSI processes available at that time. Thus, some elements of the system are now obsolete and, in particular, only a small number of the network receivers (TTCrx) is presently available to be deployed in the LHC experiments. In this paper we describe a possible implementation of the TTCrx, which should be used to replace the TTCrx chips on the off-detector electronics, where radiation is not a concern. Our design is based on the Xilinx Virtex-5 FPGAs, and uses fabric resources and embedded high speed serial link transceivers, in order to emulate the architecture and the main features of the TTCrx. By using our approach, the receiver part of the TTC can be easily implemented in commercial FPGAs, thus resulting in a fast design implementation, a simple layout and a cost-effective solution. In this paper, we present the details of the implementation and the test results.
    Journal of Instrumentation 02/2013; 8(02):T02003. · 1.66 Impact Factor
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    ABSTRACT: The NEutrino Mediterranean Observatory-Submarine Network 1 (NEMO-SN1) seafloor observatory is located in the central Mediterranean Sea, Western Ionian Sea, off Eastern Sicily (Southern Italy) at 2100-m water depth, 25 km from the harbor of the city of Catania. It is a prototype of a cabled deep-sea multiparameter observatory and the first one operating with real-time data transmission in Europe since 2005. NEMO-SN1 is also the first-established node of the European Multidisciplinary Seafloor Observatory (EMSO), one of the incoming European large-scale research infrastructures included in the Roadmap of the European Strategy Forum on Research Infrastructures (ESFRI) since 2006. EMSO will specifically address long-term monitoring of environmental processes related to marine ecosystems, climate change, and geohazards. NEMO-SN1 has been deployed and developed over the last decade thanks to Italian funding and to the European Commission (EC) project European Seas Observatory NETwork-Network of Excellence (ESONET-NoE, 2007-2011) that funded the Listening to the Deep Ocean-Demonstration Mission (LIDO-DM) and a technological interoperability test (http://www.esonet-emso.org). NEMO-SN1 is performing geophysical and environmental long-term monitoring by acquiring seismological, geomagnetic, gravimetric, accelerometric, physico-oceanographic, hydroacoustic, and bioacoustic measurements. Scientific objectives include studying seismic signals, tsunami generation and warnings, its hydroacoustic precursors, and ambient noise characterization in terms of marine mammal sounds, environmental and anthropogenic sources. NEMO-SN1 is also an important test site for the construction of the Kilometre-Cube Underwater Neutrino Telescope (KM3NeT), another large-scale research infrastructure included in the ESFRI Roadmap based on a large volume neutrino telescope. The description of the observatory and its most recent implementations is presented. On June 9, 2012, NEMO-SN1 was successfully de- loyed and is working in real time.
    IEEE Journal of Oceanic Engineering 01/2013; 38(2):358 - 374. · 1.16 Impact Factor
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    IEEE Journal of Oceanic Engineering 01/2013; 38(2):358-374. · 1.16 Impact Factor
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    ABSTRACT: A recent analysis of the Fermi Large Area Telescope data provided evidence for a high intensity emission of high-energy gamma rays with a E�2 spectrum from two large areas, spanning 50� above and below the Galactic centre (the ‘‘Fermi bubbles’’). A hadronic mechanism was proposed for this gamma-ray emission making the Fermi bubbles promising source candidates of high-energy neutrino emission. In this work Monte Carlo simulations regarding the detectability of high-energy neutrinos from the Fermi bubbles with the future multi-km3 neutrino telescope KM3NeT in the Mediterranean Sea are presented. Under the hypothesis that the gamma-ray emission is completely due to hadronic processes, the results indicate that neutrinos from the bubbles could be discovered in about one year of operation, for a neutrino spectrum with a cutoff at 100 TeV and a detector with about 6 km3 of instrumented volume. The effect of a possible lower cutoff is also considered.
    Astroparticle Physics 11/2012; 42(2013):7-14. · 4.78 Impact Factor
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    ABSTRACT: Dense wavelength division multiplexing (DWDM) is an optical technology that allows transmitting across a fiber many wavelengths, which can be added and dropped by means of passive optical components. We present and discuss the performance of a complex DWDM network data transmission system that will find an application in the NEMO underwater neutrino telescope. The tests cover the qualification of a complete multipoint DWDM network consisting of transponders, fibers, passive optical filters, and an optical amplifier. The behavior of the network is evaluated in the final arrangement by means of bit error ratio (BER) and optical signal-to-noise ratio measurements at 800 Mb/s rate. In order to test the network, a board, developed for the NEMO experiment, has been used. A custom DWDM module, capable of data rates up to 1.4 Gb/s and specifically designed for real-time data acquisition systems, can be hosted by the board. A dedicated application runs on the board programmable logic controlling the module, monitoring the transceiver's functionalities and running the BER test.
    IEEE Transactions on Nuclear Science 04/2012; 59(2):251-255. · 1.22 Impact Factor
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    ABSTRACT: SuperB is a novel, high-luminosity (1036 cm-2s-1), asymmetric e+e- collider to be built at the future Cabibbo Laboratory, in the campus of the University of Rome Tor Vergata (Italy). A detector aimed at studying the B physics will be installed in this facility. High-speed serial links will be used for trigger, control and data read-out. The on-detector ends of the links will have to withstand a hadron fluence of 8 · 1010 cm-2 per effective year (107 s). In this work, we present results of irradiation tests on off-the-shelf optical transceivers, candidate for deployment in SuperB. We irradiated the components with a 62-MeV proton beam at INFN Laboratori Nazionali del Sud (Catania, Italy). By means of our setup, we recorded parameters such as BER, drawn current and optical power, for the laser and for the photodiode, as a function of the absorbed dose. We discuss our results in the view of the deployment of the considered components in the SuperB experimental apparatus.
    Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2012 IEEE; 01/2012
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    ABSTRACT: The ANTARES Neutrino Telescope was completed in May 2008 and is the first operational Neutrino Telescope in the Mediterranean Sea. The main purpose of the detector is to perform neutrino astronomy and the apparatus also offers facilities for marine and Earth sciences. This paper describes the design, the construction and the installation of the telescope in the deep sea, offshore from Toulon in France. An illustration of the detector performance is given.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 11/2011; 656(1):11–38. · 1.14 Impact Factor
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    ABSTRACT: The KM3NeT project aims to construct a multi-cubic-kilometre scale neutrino telescope in the Mediterranean Sea. The telescope’s detection units, deployed in the deep sea, will be instrumented with optical modules, each housing 31 three-in. photomultiplier tubes (PMTs). Three companies are developing new types of 3in. PMTs for the KM3NeT project. The first PMT samples of type R6233 mod. have been delivered from Hamamatsu and tested at the Erlangen Centre for Astroparticle Physics and at Nikhef. The results of these tests are presented. Many of the parameters of the existing versions of these PMTs already meet the KM3NeT requirements and production versions will be used to build the first developmental optical modules. Hamamatsu have started the development of new versions of PMTs of current interest, with better timing parameters and as lightly larger photocathode. The first two examples of a new PMT from ET Enterprises are under tests at Nikhef. The delivery of first 82 mm diameter PMTs from MELZ is also expected in October 2011. To increase photodetection efficiency in the multi-PMT optical module, PMTs will be surrounded by reflective light gathering rings (‘expansion cones’). Test results of such an assembly are also presented.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 11/2011; 695(2012):313-316. · 1.14 Impact Factor
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    ABSTRACT: NEMO-SN1, located in the central Mediterranean Sea, Western Ionian Sea, off Eastern Sicily Island (Southern Italy) at 2100 m water depth, 25 km from the harbour of the city of Catania, is a prototype of a cabled deep-sea multiparameter observatory and the first operating with real-time data transmission in Europe since 2005. NEMO-SN1 is also the first-established node of EMSO (European Multidisciplinary Seafloor Observatory, http://emso-eu.org), one of the incoming European large-scale research infrastructure included since 2006 in the Roadmap of the ESFRI (European Strategy Forum on Research Infrastructures, http://cordis.europa.eu/esfri/roadmap.htm), which will specifically address long-term monitoring of environmental processes related to Marine Ecosystems, Climate Change and Geo-hazards. NEMO-SN1 has been deployed and developed over the last decade thanks to Italian resources and to the EC project ESONET-NoE (European Seas Observatory NETwork - Network of Excellence, 2007-2011) that funded the LIDO-DM (Listening to the Deep Ocean - Demonstration Mission) and a technological interoperability test (http://www.esonet-emso.org/esonet-noe/). NEMO-SN1 is performing geophysical and environmental long-term monitoring by acquiring seismological, geomagnetic, gravimetric, accelerometric, physico-oceanographic, hydro-acoustic, bio-acoustic measurements specifically related to earthquakes and tsunamis generation and ambient noise characterisation in term of marine mammal sounds, environmental and anthropogenic sources. A further main feature of NEMO-SN1 is to be an important test-site for the construction of KM3NeT (Kilometre-Cube Underwater Neutrino Telescope, http://www.km3net.org/), another large-scale research infrastructure included in the ESFRI Roadmap constituted by a large volume neutrino telescope. The description of the observatory and the most recent data acquired will be presented and framed in the general objectives of EMSO.
    Underwater Technology (UT), 2011 IEEE Symposium on and 2011 Workshop on Scientific Use of Submarine Cables and Related Technologies (SSC); 05/2011
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    ABSTRACT: In a deep-sea neutrino telescope it is mandatory to locate the position of the optical sensors with a precision of about 10 cm. To achieve this requirement, an innovative Acoustic Positioning System (APS) has been designed in the frame work of the KM3NeT neutrino telescope. The system will also be able to provide an acoustic guide during the deployment of the telescope's components and seafloor infrastructures (junction boxes, cables, etc.). A prototype of the system based on the successful acoustic systems of ANTARES and NEMO is being developed. It will consist of an array of hydrophones and a network of acoustic transceivers forming the Long Baseline. All sensors are connected to the telescope data acquisition system and are in phase and synchronised with the telescope master clock. Data from the acoustic sensors, continuously sampled at 192 kHz, will be sent to shore where signal recognition and analysis will be carried out. The design and first tests of the system elements will be presented. This new APS is expected to have better precision compared to the systems used in ANTARES and NEMO, and can also be used as a real-time monitor of acoustic sources and environmental noise in deep sea.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 01/2011; 662(Supplement 1):S246–S248. · 1.14 Impact Factor
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    ABSTRACT: Many high energy physics experiments (Auger, Ice-Cube, Km3Net) currently taking data or planned in the near future consist of big and sparse detectors that acquire a huge amount of data. This kind of topology requires the ability to acquire physics information in different places of the detector and correlate them using the occurrence time, usually with a sub-ns precision. In some cases this can be done using commercially available technologies, for instance the Auger experiment uses a GPS receiver in each surface tank to “time stamp” the produced data, but in many cases this is not possible. In underwater or underground detectors the GPS signal cannot reach the apparatus so a different approach must be used. In order to minimize the number of physical links and to guarantee the timing synchronization of the apparatus, data and clock information can be transmitted over the same serial stream. This work presents a synchronous link with fixed and deterministic latency based on the embedded transceivers of the Xilinx Virtex-5 FPGA family. This communication channel is used to implement the data acquisition system for the NEMO experiment. The whole timing distribution chain has been taken into consideration to assess the performance of the readout electronics in terms of timing resolution. The system clock distributed at every level of the apparatus has been derived by a precise timing generator during the characterization phase and by the signals provided by a GPS receiver during the operating configuration. The overall timing performance comply with the requirements of the experiment, yielding a rms timing resolution of about 20 ps.
    01/2011;
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    ABSTRACT: An innovative Acoustic Positioning System for the km3-scale neutrino telescope has been designed and is under realization within the KM3NeT Consortium. Compared to the Acoustic Positioning Systems used for the km3 demonstrators, ANTARES and NEMO Phase 1, this new system is based on the “all data to shore” concept and it will permit the enhancement of detector positioning performances, reduction of costs and its use as real-time monitor of environmental acoustic noise.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 01/2011; 626. · 1.14 Impact Factor
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    ABSTRACT: The Timing Trigger and Control (TTC) system is a crucial part of all the experiments at the Large Hadron Collider (LHC). It is an optical distribution network which delivers to the detectors' electronics, with low jitter and skew, the timing and synchronization signals of the LHC machine and the trigger information of the experiments.
    01/2011;