35165869
The cosmic ray proton, helium and CNO fluxes in the 100 TeV energy region from TeV muons and EAS atmospheric Cherenkov light observations of MACRO and EAS-TOP
The primary cosmic ray (CR) proton, helium and CNO fluxes in the energy range 80-300 TeV are studied at the National Gran Sasso Laboratories by means of EAS-TOP (Campo Imperatore, 2005 m a.s.l.) and MACRO (deep underground, 3100 m w.e., the surface energy threshold for a muon reaching the detector being E-mu(th) approximate to 1.3 TeV). The measurement is based on: (a) the selection of primaries based on their energy/nucleon (i.e., with energy/nucleon sufficient to produce a muon with energy larger than 1.3 TeV) and the reconstruction of the shower geometry by means of the muons recorded by MACRO in the deep underground laboratories; (b) the detection of the associated atmospheric Cherenkov light (C.l.) signals by means of the C.l. detector of EAS-TOP. The C.l. density at core distance r > 100 m is directly related to the total primary energy E-0. Proton and helium ("p + He") and proton, helium and CNO ("p + He + CNO") primaries are thus selected at E-0 approximate to 80 TeV, and at E-0 similar or equal to 250 TeV, respectively. Their flux is measured: J(p+He)(80 TeV) = (1.8 +/- 0.4) x 10(-6) m(-1)-s(-1) sr(-1) TeV-1, and J(p+He+CNO)(250 TeV) = (1.1 +/- 0.3) x 10(-7) m(-2)-s(-1) sr(-1) TeV-1, their relative weights being J(p+He)(J(p+He+CNO)) over bar (250 TeV) = 0.78 +/- 0.17. By using the measurements of the proton spectrum obtained from the direct experiments and hadron flux data in the atmosphere, we obtain for the relative weights of the three components at 250 TeV: J(p) : J(He) : J(CNO) = (0.20 +/- 0.08) : (0.58 +/- 0.19) : (0.22 +/- 0.17). This corresponds to the dominance of helium over proton primaries at 100-1000 TeV, and a possible non-negligible contribution from CNO. The lateral distribution of Cherenkov light in Extensive Air Showers (EASs), which is related to the rate of energy deposit of the primary in the atmosphere, is measured for a selected proton and helium primary beam, and good agreement is found when compared with the one calculated with the CORSIKA/QGSJET simulation model. (C) 2004 Elsevier B.V. All rights reserved.
8791824
Detection of high energy cosmic rays with the resonant gravitational wave detectors NAUTILUS and EXPLORER
Abstract The cryogenic resonant gravitational wave detectors NAUTILUS and EXPLORER, made of an aluminum alloy bar, can detect cosmic ray showers. At temperatures above 1 K, when the material is in the normal-conducting state, the measured signals are in good agreement with the expected values based on the cosmic rays data and on the thermo-acoustic model. When NAUTILUS was operated at the temperature of 0.14 K, in superconductive state, large signals produced by cosmic ray interactions, more energetic than expected, were recorded. The NAUTILUS data in this case are in agreement with the measurements done by a dedicated experiment on a particle beam. The biggest recorded event was in EXPLORER and excited the first longitudinal mode to a vibrational energy of ∼670 K, corresponding to ∼360 TeV absorbed in the bar. Cosmic rays can be an important background in future acoustic detectors of improved sensitivity. At present, they represent a useful tool to verify the gravitational wave antenna performance.
122862116
EXPLORER and NAUTILUS gravitational wave detectors: a status report
The two cryogenic resonant bar detectors of the ROG Collaboration, EXPLORER and NAUTILUS, have been taking data continuously with a high duty cycle for several years. We report here on the status of recent analysis of the data and in particular on the results of the burst searches in the year 2004.
59335104
RAP: thermoacoustic detection at the DAΦNE beam test facility
In order to investigate the anomalous response at ultra-low temperatures of the resonant-mass gravitational wave detector NAUTILUS, the RAP experiment has been planned to measure the vibrations in a small cylindrical aluminium bar when hit by 105 510 MeV electrons from the DAΦNE beam test facility, corresponding to the energies released by typical extensive air showers. The results of the measurement at low temperature and in the superconducting regime are crucial to understand the interaction of ionizing particles with bulk superconductors and to confirm the results on the thermoacoustic model of the past experiments. The first run of RAP experiment is scheduled for the end of June. The scheme of operation and the preliminary results at room temperature will be presented.
121773371
Muon tracking underground
SummaryWe present a new design of plastic streamer tubes, optimized to match the experimental requirements of large-area under-ground detectors, where muon identification is needed with good angular resolution.RiassuntoSi descrive un nuovo disegno di tubi a streamer in plastica, ottimizzati per le esigenze sperimentali di apparati sotterranei di grande area, dove si richiede l'identificazione di muoni con buona risoluzione angolare.РзюмеПредлагается новый проект пластических стримерных трубок, оптимально согласованный с эксперименталыми требованиями подэемных детекторов на большой площади, когда небходима идентификция мюоноб с высокими угловым разрешением.
118375535
Comparison of muon and neutrino times from decays of mesons in the atmosphere
We propose a test to compare the speed of muons and muon neutrinos produced in the same bundles in the atmosphere. By comparing the arrival times of primary muons and muons induced by neutrinos, experiments such as Super-Kamiokande, IceCube and ANTARES could verify recent hints on the possibility that neutrinos have a velocity larger than the speed of light. For smaller detectors such as MINOS and OPERA, where it may be challenging to recognize downgoing muons induced by neutrinos inside the active volume, another measurement may be possible thanks to the ns-time resolution. The arrival times of muons in a bundle produced by one cosmic ray interaction in the atmosphere should return a value compatible with the time resolution, while if neutrinos have larger velocity than muons some of the muons may arrive slightly earlier in a bundle of particles than others.
122635454
Calibration of the CMS drift tube chambers and measurement of the drift velocity with cosmic rays
This paper describes the calibration procedure for the drift tubes of the CMS barrel muon system and reports the main results obtained with data collected during a high statistics cosmic ray data-taking period. The main goal of the calibration is to determine, for each drift cell, the minimum time delay for signals relative to the trigger, accounting for the drift velocity within the cell. The accuracy of the calibration procedure is influenced by the random arrival time of the cosmic muons relative to the LHC clock cycle. A more refined analysis of the drift velocity was performed during the offline reconstruction phase, which takes into account this feature of cosmic ray events.
209834924
Performance of CMS Muon Reconstruction in Cosmic-Ray Events
The performance of muon reconstruction in CMS is evaluated using a large data sample of cosmic-ray muons recorded in 2008. Efficiencies of various high-level trigger, identification, and reconstruction algorithms have been measured for a broad range of muon momenta, and were found to be in good agreement with expectations from Monte Carlo simulation. The relative momentum resolution for muons crossing the barrel part of the detector is better than 1% at 10 GeV/c and is about 8% at 500 GeV/c, the latter being only a factor of two worse than expected with ideal alignment conditions. Muon charge misassignment ranges from less than 0.01% at 10 GeV/c to about 1% at 500 GeV/c.
119371614
Computing System for the Belle Experiment
We describe the offline computing system of the Belle experiment, consisting of a computing farm with one thousand IA-32 CPUs. Up to now, the Belle experiment has accumulated more than 120 fb$^{-1}$ of data, which is the world largest $B\bar{B}$ sample at the $\Upsilon(4S)$ energy. The data have to be processed with a single version of reconstruction software and calibration constants to perform precise measurements of $B$ meson decays. In addition, Monte Carlo samples three times larger than the real beam data are generated. To fullfill our computing needs, we have constructed the computing system with 90(300) quad(dual) CPU PC servers from multiple vendors as a central processing system. The details of this computing system and performance of data processing with the current model are presented.
124415481
Moments of the photon energy spectrum from B --> X(s gamma) decays measured by BELLE
120842822
Study of sparking in Micromegas chambers
Abstract The discharge properties of Micromegas detector are studied in detail. Tests have demonstrated that the origin of discharges in hadron beams is mainly associated with nuclear interactions of the incident particle with the gas of the detector. Use of low average Z gas mixtures diminishes the spark rate. The streamer discharge model of Raether has been proved to be valid for this detector. A detector polarization which minimizes the spark energy is proposed. Gas and geometry factors improving the discharge limit are discussed.