19567091
A search for neutrino emission from the Fermi bubbles with the ANTARES telescope
Analysis of the Fermi-LAT data has revealed two extended structures above and below the Galactic Centre emitting gamma rays with a hard spectrum, the so-called Fermi bubbles. Hadronic models attempting to explain the origin of the Fermi bubbles predict the emission of high-energy neutrinos and gamma rays with similar fluxes. The ANTARES detector, a neutrino telescope located in the Mediterranean Sea, has a good visibility to the Fermi bubble regions. Using data collected from 2008 to 2011 no statistically significant excess of events is observed and therefore upper limits on the neutrino flux in TeV range from the Fermi bubbles are derived for various assumed energy cutoffs of the source.
118473267
A parameterisation of the flux and energy spectrum of single and multiple muons in the deep water or ice
Abstract Atmospheric muons play an important role in underwater/ice neutrino detectors. A parameterisation of the flux of single and multiple muon events, of their lateral distribution and energy spectrum is presented. The kinematics parameters were modelled starting from a full Monte Carlo simulation of the interaction of primary cosmic rays with atmospheric nuclei. The parametric formulas are valid for a vertical depth of 1.5–5 km w.e. and up to 85 ∘ for the zenith angle, and can be used as input for a fast simulation of atmospheric muons in underwater/ice detectors.
110859812
The Central Logic Board and its auxiliary boards for the optical module of the KM3Net detector
The KM3Net neutrino telescope will be composed of many optical modules, each of them containing 31 (3") photomultipliers, connected to a Central Logic Board. The Central Logic Board integrates Time to Digital Converters that measure Time over Threshold of the photomultipliers signals while White Rabbit is used for the optical modules time synchronization. Auxiliary boards have also been designed and built in order to test and extend the performance of the Central Logic Board. The Central Logic Board, as well as the auxiliary boards, will be presented by focusing on the design consideration, prototyping issues and tests.
120966174
The NEMO project: A status report
Abstract The latest results and the activities towards the construction of a km 3 Cherenkov neutrino detector carried out by the NEMO Collaboration are described. Long-term exploration of a 3500 m deep-sea site close to the Sicilian coast has shown that it is optimal for the installation of the detector. The NEMO Phase-1 project has validated several technologies proposed for the construction of the km 3 detector on a test site at 2000 m depth. The new infrastructure on the candidate Capo Passero site set up as part of the Phase-2 project will provide the possibility to test detector components at 3500 m depth.
55753733
Measurement of the atmospheric muon depth intensity relation with the NEMO Phase-2 tower
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. Cerenkov 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.
120456193
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.
121746448
A comparison of the charge division and timing difference techniques in streamer mode
Abstract Resolutions of σ = ±3 mm and non-linearities of less than 5 mm have been measured over 99% of the length of 4 m streamer tubes by timing difference. In comparison charge division measurements give σ = ±1.4 mm at the centre of the tube decreasing to ±3mm at the ends of the tube, with non-linearities less than 5 mm. Both measurements were obtained with 35 m of coaxial cable between the detector and the active electronics.
122729021
E2 nuclear resonance effects in pionic and kaonic atoms
Abstract The attenuation due to the E2 nuclear resonance effect has been measured in hadronic atoms using pions with 111 Cd and 112 Cd, and for kaons with 122 Sn. Energies of the relevant X-ray and γ-ray transitions and of the X-ray cascade intensities have also been measured so as to give a self-consistent set of information. The results are found to be in very good agreement with theoretical calculations.
122363641
Observation of kaonic hydrogen atom X-rays
Abstract A special liquid-hydrogen target has been used with a stopping kaon beam in order to search for the X-rays from kaonic hydrogen atoms. A peak at 6.52 ± 0.06 keV, consistent with the unshifted energy of 2p-1s X-rays from K − −p atoms, has been observed with a yield of about 0.1%. The energy shift would imply rather small values for the real K − −p scattering length at threshold.
120330344
High accuracy measurements of drift time in the streamer mode
Abstract A nitrogen laser focused to a 50 μm spot diameter with a minimum ionising energy deposit was used to scan a streamer tube. Results were obtained for the drift velocity and the spatial resolution. The resolution averaged, σ = ±25 μ m over the total drift length of 8 mm at atmospheric pressure. The charge multiplication region was also observed and could be separated into two regions, a region of low charge multiplication with increased drift velocity and an avalanche region with constant drift time.
119337869
Accurate three-dimensional simulation of straw chambers using slow, medium and fast gas mixtures
Abstract The positional accuracy and efficiency of straw chambers using gas mixtures of carbon dioxide-isobutane (80:20), argon-isobutane-isopropanol (50:49:1) and argon-carbon tetrafluoride (90:10) are calculated as a function of drift distance with a precision of 1%. Large attachment effects on the resolution and efficiency are predicted for carbon-tetrafluoride-based gas mixtures which are important for SSC applications. The varying electric field in straw chambers leads to nonlinear drift time-distance relationships. The accurate prediction of this relationship to about 1% should allow the track fitting analysis to proceed with more tightly constrained parameters.