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.
120208422
The KM3NeT Project
The KM3NeT consortium has been carrying on R&D activities towards the construction of a km3 scale deep sea neutrino telescope to detect high-energy astrophysical neutrinos. It will complement the IceCube detector, already in operation at the South Pole, and will have the Galactic centre and most of the Galactic plane in its field of view. Recently a technical design report has been released which contains the general description of the KM3NeT deep sea research infrastructure. This research facility will represent also a multidisciplinary marine and Earth science observatory, hosting a network of nodes for long term continuous monitoring of the deep sea environment. The objectives, status and plans of the KM3NeT project are presented.
118568116
Updated limits on diffuse fluxes of cosmic neutrinos with 2008-2011 ANTARES data
The ANTARES neutrino telescope detects the Cherenkov radiation emitted along the path of charged particles produced in neutrino interactions. ANTARES is sensitive to all flavors even though it is optimized for muon neutrinos. Several algorithms estimating the deposited energy in the active volume of the detector have been developed and applied to the reconstruction of the primary neutrino energy - this allows to improve the search for a diffuse flux of astrophysical neutrinos. The search for a diffuse flux of cosmic neutrinos at very high energies (E_\nu > 30 TeV) is updated using 4 years of data with the full detector.
110097009
The trigger and data acquisition for the NEMO-Phase 2 tower
In the framework of the Phase 2 of the NEMO neutrino telescope project, a tower with 32 optical modules is being operated since march 2013. A new scalable Trigger and Data Acquisition System (TriDAS) has been developed and extensively tested with the data from this tower. Adopting the all-data-to-shore concept, the NEMO TriDAS is optimized to deal with a continuous data-stream from off-shore to on-shore with a large bandwidth. The TriDAS consists of four computing layers: (i) data aggregation of isochronal hits from all optical modules; (ii) data filtering by means of concurrent trigger algorithms; (iii) composition of the filtered events into post-trigger files; (iv) persistent data storage. The TriDAS implementation is reported together with a review of dedicated on-line monitoring tools.
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.
123652458
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 Earth's 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.
56301921
High rate behavior and discharge limits in micro-pattern detectors
Abstract We present and discuss a set of systematic measurements, carried out with gaseous proportional micro-pattern detectors, in order to assess their maximum gain when irradiated with high-rate soft X-rays and heavily ionizing alpha particles. The inventory of detectors tested includes: micro-strips, micromegas, micro-dot, gas electron multiplier, CAT (compteur a trous), trench (or groove), micro-CAT (or WELL) detectors, as well as systems with two elements of gaseous amplification in cascade. We confirm the general trend of all single-stage detectors to follow Raether's criterion, i.e. a spontaneous transition from avalanche to streamer, followed by a discharge, when the avalanche size reaches a value of a few 10 7 ; a noticeable exception is the micro-dot counter holding more than 10 8 . In multiple structures, where the gain is shared between two devices in cascade, the maximum overall gain under irradiation is increased by at least one order of magnitude; we speculate this to be a consequence of a voltage dependence of Raether's limit, larger for low operating potentials. Our conclusion is that only multiple devices can guarantee a sufficient margin of reliability for operation in harsh LHC running conditions.
109752350
Operation of thin effective substrate microstrip gas avalanche chambers
Recent advances in Multiwire Proportional Chambers have resulted in the Microstrip Gas Avalanche Chambers (MSGC's). This paper describes recent measurements of the performance of such chambers, fabricated on a Si substrate, in test beam conditions.
53630528
Simulation of VUV electroluminescence in micropattern gaseous detectors: the case of GEM and MHSP
Electroluminescence produced during avalanche development in gaseous avalanche detectors is a useful information for triggering, calorimetry and tracking in gaseous detectors. Noble gases present high electroluminescence yields, emitting mainly in the VUV region. The photons can provide signal readout if appropriate photosensors are used. Micropattern gaseous detectors are good candidates for signal amplification in high background and/or low rate experiments due to their high electroluminescence yields and radiopurity. In this work, the VUV light responses of the Gas Electron Multiplier and of the Micro-Hole & Strip Plate, working with pure xenon, are simulated and studied in detail using a new and versatile C++ toolkit. It is shown that the solid angle subtended by a photosensor placed below the microstructures depends on the operating conditions. The obtained absolute EL yields, determined for different gas pressures and as functions of the applied voltage, are compared with those determined experimentally.
120592230
A multiterm Boltzmann analysis of drift velocity, diffusion, gain and magnetic-field effects in argon-methane-water-vapour mixtures
Abstract The effect of adding water vapour to argon-methane mixtures used in TPC-type detectors is investigated using the exact multiterm Boltzmann expansion. The transverse and longitudinal diffusion coefficients and the drift velocity are calculated with an accuracy of ± 3, ± 2 and ± 1% respectively. The calculations are extended into the avalanche region and compared to avalanche gain measurements. The effect of misalignment of the electric and magnetic fields on the drift direction is also investigated.
108832091
The microdot gas avalanche chamber: an investigation of new geometries
Abstract The gains of the microstrip and microgap gas avalanche chambers are limited to below gains of 5 × 10 3 by geometrical and gas properties. In order to increase the maximum gain to greater than 2 × 10 4 a new detector geometry, the microdot, is proposed that can be produced at a standard silicon MOS microfabrication facility at similar cost to present microstrip gas detectors. In addition to charged particle tracking, the new geometry is also well suited to imaging applications. The operating characteristics of the new device have been investigated using a numerical simulation and a comparison with conventional strip geometries is presented. These results show that the microdot geometry reaches higher gas gains than the strip-like geometries, for the same set of electrode potentials, with a reduced cathode electric field enhancing operational stability.