M. Mongelli

The Data Acquisition and Transport Design for NEMO Phase 1

The NEMO collaboration proposes to build an underwater neutrino telescope located South-East off the Sicily coast. This paper describes the concepts underlying the communication link design going over the whole data acquisition and transport from the front-end electronics to the module sending data on-shore through a fiber optic link which relies on Dense Wavelength Division Multiplexing. An on-shore board, plugged into a PC, extracts and distributes data both to first-level trigger and control systems. Underwater apparatus monitoring and controls are guaranteed by oceanographic instruments and dedicated sensors, whose data are packed and sent back to shore using the same optical link. The communication is fully bidirectional, allowing transmission of timing and control commands. The architecture described here provides a complete real-time data transport layer between the onshore laboratory and the underwater detector. During winter 2006 a first prototype of the apparatus has been deployed: calibration results from the currently working system are here reported.

Preliminary results of the LAT Calibration Unit beam tests

The calibration strategy of the GLAST Large Area Telescope (LAT) combines analysis of cosmic ray data with accelerator particle beams measurements. An advanced Monte Carlo simulation of the LAT, based on the Geant4 package, was set up to reproduce the LAT response to such radiation and to benchmark the event reconstruction and the background rejection strategy before launch and during operation. To validate the LAT simulation, a massive campaign of beam tests was performed between July and November 2006, in parallel with the LAT integration and test, on the LAT Calibration Unit. This is a detector built with spare flight modules and flight‐like readout electronics, which was exposed to a large variety of beams, representing the whole spectrum of the signal that will be detected by the LAT, using the CERN and the GSI accelerator facilities. Beams of photons (0 – 2.5 GeV), electrons (1 – 300 GeV), hadrons (π and p, a few GeV – 100 GeV) and ions (C; Xe, 1.5 GeV/n) were shot through the CU to measure the phys...

A high rejection transition radiation detector prototype to distinguish positrons from protons in a cosmic ray space laboratory

Abstract We have carefully implemented a transition radiation detector prototype in order to design a similar device having 75 × 150 cm 2 active surface that will discriminate positrons from protons. This detector will be part of the spectrometer of the experiment WIZARD, planned to fly at 180 miles altitude on the NASA Space Station “FREEDOM” to search for primordial antimatter. Since the positron to proton ratio is expected to be of the order of 10 −4 , we have pushed the proton rejection factor of the spectrometer beyond this value using a compact transition radiation detector equipped with properly designed “cluster counting” electronics.

STRAW CHAMBERS OPERATING IN VACUUM FOR PARTICLE TRACKING AND TRANSITION RADIATION DETECTION IN ACCELERATOR AND SPACE EXPERIMENTS

We have designed and tested some straw tubes prototype detectors to investigate the possibility to operate a full size chamber with extremely reduced gas leaks in a high vacuum environment in accelerator experiments or in sealed mode for astroparticle physics researches in outer space. After completing the tests we have finally built a tracking detector of 1300 channels which has run in a vacuum chamber in the experiment E864 at BNL with a leak of 7 × 10−3Torr l/s compatible with the permeability of the materials used.

A transition radiation detector for positron identification in a balloon-borne particle astrophysics experiment

Abstract We have built and tested a transition radiation detector of about 76 × 80 cm 2 active surface to discriminate positrons from protons in an experiment performed on a balloon flight to search for primordial antimatter. The TRD is made of ten modules each consisting of a carbon fiber radiator followed by a multiwire proportional chamber. In order to achieve a proton-electron rejection factor of the order of 10 −3 with a strict limitation on power consumption to about 40 mW per chamber channel, as required by experimental constraints, we have developed a low power consumption “cluster counting” electronics. Different analysis procedures of calibration data are shown. In addition, comparisons of the performances of this detector are also made with a previous similar prototype equipped with standard fast electronics and similar detectors from other authors.

NEMO: A PROJECT FOR A KM3 UNDERWATER DETECTOR FOR ASTROPHYSICAL NEUTRINOS IN THE MEDITERRANEAN SEA

The status of the project is described: the activity on long term characterization of water optical and oceanographic parameters at the Capo Passero site candidate for the Mediterranean km3 neutrino telescope; the feasibility study; the physics performances and underwater technology for the km3; the activity on NEMO Phase 1, a technological demonstrator that has been deployed at 2000 m depth 25 km offshore Catania; the realization of an underwater infrastructure at 3500 m depth at the candidate site (NEMO Phase 2).

A large area transition radiation detector to measure the energy of muons in the Gran Sasso underground laboratory

Abstract We have designed and built a transition radiation detector of 36 m2 area in order to measure the residual energy of muons penetrating in the Gran Sasso cosmic ray underground laboratory up to the TeV region. It consists of three adjacent modules, each of 2 × 6 m2 area. Polystyrene square tubes, filled with a argon-carbon dioxide gas mixture, and polyethylene foam layers are used as proportional detectors and radiators respectively. We cover such a large surface with only 960 channels that provide adequate energy resolution and particle tracking for the astroparticle physics items to investigate. The detector has been calibrated using a reduced size prototype in a test beam. Results from one module exposed to cosmic rays at sea level are shown.

A transition radiation detector for electron identification in a high energy experiment

Abstract We have built a transition radiation detector consisting of four sets of multilayered polyethylene radiators each followed by a xenon-filled proportional chamber. This detector has been used in a hadron-proton scattering experiment at CERN SPS to discriminate electrons from hadrons in the final state. Using the technique of recording chamber signals of amplitude exceeding a fixed threshold we normally achieved 0.5% pion contamination at 80% electron efficiency.

Status and first results of the NEMO Phase-2 tower

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.

The optical modules of the phase-2 of the NEMO project

A 13-inch Optical Module (OM) containing a large-area (10-inch) photomultiplier was designed as part of Phase-2 of the NEMO project. An intense R&D activity on the photomultipliers, the voltage supply boards, the optical coupling as well as the study of the influences of the Earths magnetic field has driven the choice of each single component of the OM. Following a well-established production procedure, 32 OMs were assembled and their functionality tested. The design, the testing and the production phases are thoroughly described in this paper.