2,028 research outputs found
Precise gain measurement of the LHCb muon chambers
No full textThe muon detector of the LHCb experiment, which will operate at the Large Hadron Collider (LHC) at CERN, consists of five muon tracking stations placed along the beam axis and equipped mainly with multi-wire proportional chambers (MWPC). In the present paper we report the results of a precise measurement of the gain of the MWPC’s as a function of the anode voltage. A precise evaluation of the primary ionization current (of about 5 pA) was performed. The absolute gain of the chambers was deduced as a function of the anode voltage and compared with the prediction of the Diethorn formula
Detailed study of the gain of the MWPCs for the LHCb muon system
No full textThe gain of a multiwire proportional chamber (MWPC) of the LHCb muon detector was measured precisely. The chamber, filled with a CO2/Ar/CF4 gas mixture, 55/40/5% in volume, was irradiated with a 1.3 GBq Cs-137 radioactive source and the current drawn by the chamber was measured. By precisely determining the primary ionization current it was possible to evaluate the absolute gain of the chamber. The dependence of the gain on the anode voltage and the gas density was measured and the need for a gain control system during the LHCb data taking is considered. Our experimental results are compared with those predicted for the chamber gain by Diethorn formula. (c) 2007 Elsevier B.V. All rights reserved
Gamma-Ray Induced Radiation Damage in Large Size BGO Crystals for the SuperB Calorimeter
No full textWe presented measurements of LY loss and recovery for different large-size BGO crystals, exposed to radiation doses of γ-rays ranging from few rad to Mrad, delivered with different dose rates. Light transmission spectra have been used to verify the underlying damage effect. © 2012 IEEE
Gas leakage and HV test procedure for the INFN Muon MWPCs
No full textThe Muon MWPCs produced by INFN laboratories are subject to gas leakage and HV tests before the installation on the LHCb experiment. The test procedure and the software tools developed are described in this paper
High resolution TPC based on optically readout GEM
No full textLarge granularity and high sensitivity commercial CMOS readout systems open the possibility of developing particle detectors with very interesting performance for different applications, from the search of rare and exotics events, such as dark matter directional candidates, to high quality neutron/ion/hadron beam monitor, mainly for medical applications. The gas scintillation mechanisms was exploited for starting an R&D on large TPC-based detector, equipped with a Triple GEM amplification stage optically readout. By this approach, a 7 l sensitive volume detector was built and tested. Space resolutions of 35μm on the GEM plane (X, Y) and 100μm on Z and energy measurements with a precision of about 25% were obtained. Analysis of the track shapes provides precious information allowing very good particle discrimination
Measurement of the D+/- production asymmetry in 7 TeV pp collisions
No full textThe asymmetry in the production cross-section \sigma of D+/- mesons, A_P = (\sigma(D+) - \sigma(D-))/(\sigma(D+) + \sigma(D-)), is measured in bins of pseudorapidity \eta and transverse momentum p_T within the acceptance of the LHCb detector. The result is obtained with a sample of D+ -> K_S pi+ decays corresponding to an integrated luminosity of 1.0 fb^-1, collected in pp collisions at a centre of mass energy of 7 TeV at the Large Hadron Collider. When integrated over the kinematic range 2.0 K_S pi+ decay is negligible. No significant dependence on \eta or p_T is observed
Dependence of the energy resolution of a scintillating crystal on the readout integration time
No full textThe possibilty of performing high-rate calorimetry with a slow scintillating crystal is studied. In this experimental situation, to avoid pulse pile-up, it can be necessary to base the energy measurement on only a fraction of the emitted light, thus spoiling the energy resolution. This effect was experimentally studied with a BGO crystal and a photomultiplier followed by an integrator, by measuring the maximum amplitude of the signals. The experimental data show that the energy resolution is exclusively due to the statistical fluctuations of the number of photoelectrons contributing to the maximum amplitude. When such number is small its fluctuations are even smaller than those predicted by Poisson statistics. These results were confirmed by a Monte Carlo simulation which allows to estimate, in a general case, the energy resolution, given the total number of photoelectrons, the scintillation time and the integration time
High granularity tracker based on a Triple-GEM optically read by a CMOS-based camera
No full textThe detection of photons produced during the avalanche development in gas chambers has been the subject of detailed studies in the past. The great progresses achieved in last years in the performance of micro-pattern gas detectors on one side and of photo-sensors on the other provide the possibility of making high granularity and very sensitive particle trackers.
In this paper, the results obtained with a triple-GEM structure read-out by a CMOS based sensor are described. The use of an He/CF4 (60/40) gas mixture and a detailed optimization of the electric fields made possible to obtain a very high GEM light yield. About 80 photons per primary electron were detected by the sensor resulting in a very good capability of tracking both muons from cosmic rays and electrons from natural radioactivity
MONDO: A neutron tracker for particle therapy secondary emission measurements
No full textIn Particle Therapy, cancer treatments are performed using accelerated charged particles whose high irradiation precision and conformity permit to destroy the tumour while sparing the surrounding healthy tissues. Several secondary particles are produced during the treatments mainly photons, protons and neutrons. The reduced attenuation length of neutrons yields a secondary particle sample that is larger in number when compared to photons and charged particles. Since neutrons can release a significant dose far away from the tumour region, a precise measurement of their flux, production energy and angle distributions is eagerly needed in order to improve the Treatment Planning Systems (TPS) software, so to properly take into account not only the normal tissue toxicity in the target region, but also the risk of late complications in the whole body. The MONDO (MOnitor for Neutron Dose in hadrOntherapy) project addresses the technical challenges posed by a neutron detector aiming for high detection efficiency and good backtracking precision. The main goal of the project is to develop a tracking detector targeting fast and ultra-fast secondary neutrons based on the reconstruction of two consequent elastic scattering interactions of a neutron with a target material. By reconstructing the recoiling protons, it is hence possible to measure the energy and incoming direction of the neutron using different therapeutic beams (protons, 12C ions and possibly 4He and 16O ions). The detector will be composed by a tracker realized with squared scintillating fibres and read out by a dedicated CMOS-based digital SPAD array detector. The first experimental results of a tracker demonstrator are here presented
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