26 research outputs found
The OPERA muon spectrometers
No full textThe OPERA experiment will study v, to v, oscillations through T appearance on the 732 km long CERN to Gran Sasso baseline. The magnet yokes of the two muon spectrometers are instrumented with 48 planes of high resistivity bakelite Resistive Plate Chambers (RPC) operated in streamer mode. Each plane covers about 70 m(2). A general introduction to the system installation and commissioning will be given. Four RPC planes were instrumented and the first tests were performed confirming a good behavior of the installed RPCs in terms of intrinsic noise and operating currents. The measured noise maps agree with those obtained in the extensive quality test performed at surface. Counting rates are below 20 Hz/m(2). Single and multiple cosmic muon tracks were also reconstructed. The estimated efficiency is close to the geometrical limit and the very first measurements of the absolute and differential muon flux are in agreement with the expectations. Finally, a description of the readout electronics and of the slow control system is given. (c) 2006 Elsevier B.V. All rights reserved
OPERA resistive plate chambers underground test results
No full textThe OPERA experiment [1] will study nu(mu)->nu(tau) oscillations through tau appearance on the 732 Km long CERN to Gran Sasso baseline. The magnet yokes of the two muon spectrometers are instrumented with 44 layers of high resistivity bakelite Resistive Plate Chambers (RPCs) operated in streamer mode. Each layer covers about 70 m(2). Four RPC planes were instrumented and the first tests were performed confirming a good behaviour of the installed RPCs in terms of intrinsic noise and operating currents. The measured noise maps agree with those obtained in the extensive quality tests performed at surface. Counting rates are below 20 Hz/m(2). Single and multiple cosmic muon tracks were also reconstructed. The estimated efficiency is close to the geometrical limit and the very first measurements of the absolute and differential muon flux are in agreement with expectations
Performance of a magnetized calorimeter for a long baseline neutrino oscillation experiment
No full textIn this paper we present a study of the momentum measurement ability of the magnetized calorimeter proposed for the ICANOE experiment. For the calorimeter tracker we have designed a system based on aluminum drift tubes 8.5 m long and with a square inner cross-section of 2.6 x 2.6 cm(2), fed by an Ar-CO2 gas mixture. Magnetic field measurements performed on reduced scale prototypes show that an average magnetic flux density of similar to1.3 T can be achieved. From tests with cosmic rays and beam particles, we also show that the drift tubes used for the tracker allow to. obtain spatial resolutions better than 400 mum. The muon momentum resolution achievable with the proposed layout is similar to 30%. (C) 2001 Elsevier Science B.V. All rights reserved
Long term performances of OPERA bakelite RPC system
No full textOPERA is an experiment dedicated to the observation of ν μ into ν τ oscillations through τ appearance exploiting the CNGS beam. The experiment is composed by two identical super-modules, each with a target section (made of emulsion/lead bricks alternated with a scintillator Target Tracker) and a muon spectrometer (instrumented with bakelite RPCs and drift tubes). The RPCs are operated in streamer mode with the gas mixture Ar/C 2H 2F 4/isoC 4H 10/ SF 6=75.4/20/4/0.6. The present performances of the RPC detectors are presented and the aging status of the system after four years of operation is described. The sample of events induced by the CNGS neutrino beam as well as a large sample of cosmic rays have also been used to study general properties of streamer-operated RPCs
The OPERA VETO system
No full textOPERA is an underground experiment to search for v(tau) appearance from a pure v(mu) beam produced at CERN. To flag the events due to the neutrino interactions with the rock surrounding the OPERA detector, a large VETO system, based on the use of Glass Resistive Plate Chambers (GRPCs) has been realized. We describe the VETO system, the GRPCs. the tests performed on the chambers before their installation. Presently, the VETO is in phase of commissioning. The first results of its underground operation are also presented. (C) 2008 Elsevier B.V. All rights reserved
The OPERA cosmic ray test facility at the Gran Sasso
No full textThe OPERA experiment foresees the use of about 3000m(2) of RPCs, that will be tested before the installation in a dedicated cosmic ray test facility. The test facility is composed of 2 triggering walls selecting horizontal cosmic rays muons. Each wall houses 64 glass RPCs equipped with 128 horizontal Flat Cable Strips. The z-coordinate is measured with a standard digital chain, while the x-coordinate is obtained by measuring the propagation time of the signals along the strips. In this paper the performance of the trigger walls and the first results of the RPC debug are presented
Performances of the OPERA RPCs
No full textOPERA is a dedicated experiment for the observation of v(mu) into v(tau) oscillations through tau appearance using a 730 km long baseline v(mu) beam from CERN to the Gran Sasso underground laboratory. The detector is equipped with two spectrometers for muon identification and charm background rejection. Bakelite RPCs are used as inner trackers inside the iron magnet of the spectrometers. The experiment has already performed two short runs in 2006 and 2007. Results about the RPC performances are presented. (C) 2008 Elsevier B.V. All rights reserved
Long-term operation test of RPCs for the OPERA experiment
No full textOPERA is one of the two detectors foreseen in the CERN Neutrino to Gran Sasso project, devoted to the detection of nu//mu into nu //tau oscillations in the parameter region suggested by SuperKamiokande data on atmospheric neutrinos. Bakelite RPCs will be used to instrument the iron yoke of the muon spectrometers. We present the results of long-term (greater than 6 months) streamer operations of real size OPERA RPCs at cosmic rays fluxes. Given the very low rate observed in the underground Gran Sasso Laboratories, under 3 km w.e., even this short time period is equivalent to more than 10 OPERA years. Results of tests with different gas mixtures are reported, in view of decreasing the streamer charge of operation for the RPCs employed in the experiment
The RPC system of the OPERA experiment
No full textThe OPERA experiment is designed to study the v(mu) -> v(tau) oscillation observing the v(tau) appearance in a pure v(mu) beam over a base line of 732 km from CERN to Gran Sasso Laboratory. The apparatus consists of a lead/emulsion-film target complemented by electronic detectors and muon spectrometers for muon charge and momentum measurements. The tracking inside the magnets is provide by Bakelite RPC chambers in a large scale application. The commissioning of the RPC system ended in August 2006. The paper present the layout of the RPC system and its performances. (C) 2009 Elsevier B.V. All rights reserved
LEAD/SCINTILLATING FIBER ELECTROMAGNETIC CALORIMETERS WITH 4.8%/sqrt(E[GeV])ENERGY RESOLUTION IN THE 20-80 MeV RANGE
No full textAn experimental investigation has been carried out on the properties of electromagnetic shower detectors composed of a uniform array of plastic scintillating fibers and lead (50:35 by volume ratio) for photons in the energy range 20-80 MeV. In good geometry conditions (photon hitting the fiber laterally), an energy resolution of 4.8%/square-root E[GeV] is obtained. This figure includes a 2%/square-root E[GeV] term added in quadrature due to the photoelectron statistics
