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.
62211675
PAT: The CMS Physics Analysis Toolkit
The CMS Physics Analysis Toolkit (PAT) is presented. The PAT is a high-level analysis layer enabling the development of common analysis efforts across and within Physics Analysis Groups. It aims at fulfilling the needs of most CMS analyses, providing both ease-of-use for the beginner and flexibility for the advanced user. The main PAT concepts are described in detail and some examples from physics analyses are given.
122757815
Performance Study of the CMS Barrel Resistive Plate Chambers with Cosmic Rays
In October and November 2008, the CMS collaboration conducted a programme of cosmic ray data taking, which has recorded about 270 million events. The Resistive Plate Chamber system, which is part of the CMS muon detection system, was successfully operated in the full barrel. More than 98% of the channels were operational during the exercise with typical detection efficiency of 90%. In this paper, the performance of the detector during these dedicated runs is reported.
209834639
Search for supersymmetry in events with b-quark jets and missing transverse energy in pp collisions at 7 TeV
Results are presented from a search for physics beyond the standard model based on events with large missing transverse energy, at least three jets, and at least one, two, or three b-quark jets. The study is performed using a sample of proton-proton collision data collected at sqrt(s)=7 TeV with the CMS detector at the LHC in 2011, with the missing transverse energy distribution as the principal search variable. The integrated luminosity of the sample is 4.98 inverse femtobarns. The observed number of events is found to be consistent with the standard model expectation, which is evaluated using control samples in the data. The results are used to constrain cross sections for the production of supersymmetric particles decaying to b-quark-enriched final states in the context of simplified model spectra.
199676084
Measurement of the differential q**2 spectrum and forward-backward asymmetry for B ---> K* l+ l-
118843154
Performance and operation of the CMS electromagnetic calorimeter
The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75 848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented.
119621949
Tracks storage in optical spark-chambers
Abstract A new technique in optical spark chamber pulsing is described, which allows tracks storage for a time of the order of 10 −3 sec. The mechanism producing this effect is discussed together with tests performed with different experimental conditions. The results obtained show that storage is possible with no loss in efficiency and without significant distortion of inclined tracks.
122764734
Description and performance of MEA, The magnetic detector at adone
Abstract The experimental detector at Adone, MEA, which operates with its magnetic field perpendicular to the e + e − beams is described. Studies of the magnetic compensation for operation at Adone and resulting magnetic fields are presented. Particles are detected and analyzed using narrow-gap and wide-gap spark chambers which are triggered by scintillation and proportional counters. Momentum measurements for charged particles are made with Δ / p / p = ±0.07 at p = 1 Gev/ c ( B = 2.5 kG) and angles are measured to better than ± 1.5° over a solid angle of ∼0.3 × 4 π sr.
15545142
Experimental study of high energy electron interactions in a superconducting aluminum alloy resonant bar
Peak amplitude measurements of the fundamental mode of oscillation of a suspended aluminum alloy bar hit by an electron beam show that the amplitude is enhanced by a factor ∼3.5 when the material is in the superconducting state. This result is consistent with the cosmic ray observations performed by the resonant gravitational wave detector NAUTILUS, made of the same alloy, when operated in the superconducting state. A comparison of the experimental data with the predictions of the model describing the underlying physical process is also presented.
136895496
The RAP experiment: Acoustic Detection of Particles
The RAP experiment is based on the acoustic detection of high energy particles by cylindrical bars. In fact, the interacting particles warm up the material around their track causing a local thermal expansion that, being prevented by the rest of the material, causes a local impulse of pressure. Consequently the bar starts to vibrate and the amplitude of the oscillation is proportional to the energy released. The RAP experiment has the aim to investigate the mechanical excitation of cylindrical bars caused by impinging particles depending on the conducting status of the material of which the detector is made. In particular physical phenomena related to the superconductivity state could be involved in such a way to enhance the conversion efficiency of the particle energy into mechanical vibrations. Essentially, two materials have been tested: aluminum alloy (Al5056) and niobium. In this report we report the measurements obtained for a niobium bar from room temperature down to 4K, below the transition temperature, and those obtained for an Al5056 bar above the transition (from 4 to 293 K).
125049489
A Search for prompt muons using the MACRO detector at Gran Sasso