207792360
Low energy atmospheric muon neutrinos in MACRO
Abstract We present the measurement of two event samples induced by atmospheric ν μ of average energy E ν ∼4 GeV. In the first sample, a neutrino interacts inside the MACRO detector producing an upward-going muon leaving the apparatus. The ratio of the number of observed to expected events is 0.57±0.05 stat ±0.06 syst ±0.14 theor with an angular distribution similar to that expected from the Bartol atmospheric neutrino flux. The second is a mixed sample of internally produced downward-going muons and externally produced upward-going muons stopping inside the detector. These two subsamples are selected by topological criteria; the lack of timing information makes it impossible to distinguish stopping from downgoing muons. The ratio of the number of observed to expected events is 0.71±0.05 stat ±0.07 syst ±0.18 theor . The observed deficits in each subsample is in agreement with neutrino oscillations, although the significance is reduced by the large theoretical errors. However, the ratio of the two samples causes a large cancellation of theoretical and of some systematic errors. With the ratio, we rule out the no-oscillation hypothesis at 95% c.l. Furthermore, the ratio tests the pathlength dependence of possible oscillations. The data of both samples and their ratio favor maximal mixing and Δm 2 ∼10 −3 –10 −2 eV 2 . These parameters are in agreement with our results from upward throughgoing muons, induced by ν μ of much higher energies.
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.
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.
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.
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.
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.
3266193
Belle Computing System
Abstract We describe the present status of the computing system in the Belle experiment at the KEKB e + e - asymmetric-energy collider. So far, we have logged more than 160 fb - 1 of data, corresponding to the world's largest data sample of 170 M B B ¯ pairs at the ϒ ( 4 S ) energy region. A large amount of event data has to be processed to produce an analysis event sample in a timely fashion. In addition, Monte Carlo events have to be created to control systematic errors accurately. This requires stable and efficient usage of computing resources. Here, we review our computing model and then describe how we efficiently proceed DST/MC productions in our system.
125667466
Observation of B0 ---> D+(s) pi-
124864860
Improved measurements of anti-B0 ---> D+(sJ) K- decays
123671853
Studies of CP violation in B0 ---> J / psi K*0 decays