234 research outputs found
Precise mirror alignment and basic performance of the RICH detector of the NA62 experiment at CERN
The Ring Imaging Cherenkov detector is crucial for the identification of
charged particles in the NA62 experiment at the CERN SPS. The detector
commissioning was completed in 2016 by the precise alignment of mirrors using
reconstructed tracks. The alignment procedure and measurement of the basic
performance are described. Ring radius resolution, ring centre resolution,
single hit resolution and mean number of hits per ring are evaluated for
positron tracks. The contribution of the residual mirror misalignment to the
performance is calculated.Comment: 13 pages, 10 figure
Light Detection System and Time Resolution of the NA62 RICH
A large RICH detector is used in NA62 to suppress the muon contamination in
the charged pion sample by a factor of 100 in the momentum range between 15 and
35 GeV/c. Cherenkov light is collected by 1952 photomultipliers placed at the
upstream end. In this paper the characterization of the photomultipliers and
the dedicated Frontend and Data Acquisition electronics are described, the time
resolution and the light detection efficiency measurement are presented.Comment: 15 pages, 11 figure
Mirror system of the RICH detector of the NA62 experiment
A large RICH detector is used in NA62 to suppress the muon contamination in the charged pion selection by a factor 100 in the momentum range between 15 and 35 GeV/c. The detector consists of a 17 m long tank (vessel), filled with neon gas at atmospheric pressure. Cherenkov light is reflected by a mosaic of 20 spherical mirrors with 17 m focal length, placed at the downstream end, and collected by 1952 photomultipliers (PMTs) placed at the upstream end. In this paper the characterization of the mirrors before installation and the mirror support system are described. The mirror installation procedure and the laser alignment are also illustrated
The MURAVES muon telescope: a low power consumption muon tracker for muon radiography applications
Muon Radiography or muography is based on the measurement of the absorption or scattering of cosmic muons, as they pass through the interior of large scale bodies, In particular, absorption muography has been applied to investigate the presence of hidden cavities inside the pyramids or underground, as well as the interior of volcanoes' edifices. The MURAVES project has the challenging aim of investigating the density distribution inside the summit of Mt. Vesuvius. The information, together with that coming from gravimetric measurements, is useful as input to models, to predict how an eruption may develop. The MURAVES apparatus is a robust and low power consumption muon telescope consisting of an array of three identical and independent muon trackers, which provide in a modular way a total sensitive area of three square meters. Each tracker consists of four doublets of planes of plastic scintillator bars with orthogonal orientation, optically coupled to Silicon photomultipliers for the readout of the signal. The muon telescope has been installed on the slope of the volcano and has collected a first set of data, which are being analyzed
Prospects for at CERN in NA62
The NA62 experiment will begin taking data in 2015. Its primary purpose is a
10% measurement of the branching ratio of the ultrarare kaon decay , using the decay in flight of kaons in an unseparated
beam with momentum 75 GeV/c.The detector and analysis technique are described
here.Comment: 8 pages for proceedings of 50 Years of CP
Collimation and characterization of ELI-NP gamma beam
The ELI-NP facility, currently being built in Bucharest, Romania, will deliver an intense and almost monochromatic gamma beam with tunable energy between 0.2 and 20 MeV. The challenging energy bandwidth of [Formula: see text]0.5% will be adjusted through the collimation system, while the main beam parameters will be measured through a devoted gamma-beam characterization system.[Formula: see text] The gamma-beam characterization system, designed by the EuroGammaS collaboration, consists of four elements: a Compton spectrometer that measures the gamma energy spectrum; a sampling calorimeter for a fast combined measurement of the beam average energy and its intensity, which will be used also as a monitor during machine commissioning and development; a nuclear resonant scattering system for absolute energy inter-calibration of the other detectors; and a gamma beam profile imager to be used for alignment and diagnostics purposes. The collimation and characterization system will be presented in this article. These systems have already been built and tested, while the delivery at ELI-NP facility and the final commissioning is scheduled by Fall 2018
The MURAVES Experiment: A Study of the Vesuvius Great Cone with Muon Radiography
The MURAVES experiment aims at the muographic imaging of the internal structure of the summit of Mt.
Vesuvius, exploiting muons produced by cosmic rays. Though presently quiescent, the volcano carries a
dramatic hazard in its highly populated surroundings. The challenging measurement of the rock density
distribution in its summit by muography, in conjunction with data from other geophysical techniques, can
help the modeling of possible eruptive dynamics. The MURAVES apparatus consists of an array of three
independent and identical muon trackers, with a total sensitive area of 3 square meters. In each tracker, a
sequence of 4 XY tracking planes made of plastic scintillators is complemented by a 60 cm thick lead wall
inserted between the two downstream planes to improve rejection of background from low-energy muons.
The apparatus is currently acquiring data. Preliminary results from the analysis of the first data sample are
presented
The RICH detector of the NA62 experiment at CERN
The NA62 experiment at CERN aims to measure the branching ratio of the ultra-rare charged kaon decay K+→π+νν¯ with a 10% accuracy and with a background contamination at the 10% level. Since the branching ratio of this decay is O (10 −10 ), to fulfill such request one of the main backgrounds, the decay K+→μ+ν (BR ~63% ), must be suppressed by a rejection factor of 4×10 −13 (assuming 10% signal acceptance). This can be partially accomplished using a combination of kinematical cuts (8×10 −6 ) and the different power of penetration through matter of pions and muons (10 −5 ). A further 5×10 −3 suppression factor will be provided by a RICH detector, in a momentum range between 15 and 35 GeV/c. The details of the RICH project as well as the results from test runs performed on a RICH prototype of the same length of the final detector will be presented. The current status of the construction and the description of the final readout and trigger electronics will also be reviewed
Externalities and the nucleolus
In most economic applications, externalities prevail: the worth of a coalition depends on how the other players are organized. We show that there is a unique natural way of extending the nucleolus from (coalitional) games without externalities to games with externalities. This is in contrast to the Shapley value and the core for which many different extensions have been proposed
Trapping in irradiated p-on-n silicon sensors at fluences anticipated at the HL-LHC outer tracker
The degradation of signal in silicon sensors is studied under conditions expected at the CERN High-Luminosity LHC. 200 m thick n-type silicon sensors are irradiated with protons of different energies to fluences of up to neq/cm. Pulsed red laser light with a wavelength of 672 nm is used to generate electron-hole pairs in the sensors. The induced signals are used to determine the charge collection efficiencies separately for electrons and holes drifting through the sensor. The effective trapping rates are extracted by comparing the results to simulation. The electric field is simulated using Synopsys device simulation assuming two effective defects. The generation and drift of charge carriers are simulated in an independent simulation based on PixelAV. The effective trapping rates are determined from the measured charge collection efficiencies and the simulated and measured time-resolved current pulses are compared. The effective trapping rates determined for both electrons and holes are about 50% smaller than those obtained using standard extrapolations of studies at low fluences and suggests an improved tracker performance over initial expectations
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