Litrani is a general purpose Monte-Carlo program simulating light propagation in any type of setup describable by the shapes provided by
Root. Each shape may be made of a different material. ...Dielectric constant, absorption length and diffusion length of materials may depend upon wavelength. Dielectric constant and absorption length may be anisotropic. Each face of a volume is either partially or totally in contact with a face of another volume, or covered with some wrapping having defined characteristics of absorption, reflection and diffusion. When in contact with another face of another volume, the possibility exists to have a thin slice of width
d and index
n between the two faces. The program has various sources of light: spontaneous photons, photons coming from an optical fibre, photons generated by the crossing of particles or photons generated by an electromagnetic shower. The time and wavelength spectra of emitted photons may reproduce any scintillation spectrum. As detectors, phototubes, APD, or any general type of surface or volume detectors may be specified. The aim is to follow each photon until it is absorbed or detected. Quantities to be delivered by the program are the proportion of photons detected, and the time distribution for the arrival of these, or the various ways photons may be lost.
The accuracy of the lead tungstate electromagnetic calorimeter of the CMS experiment under construction at CERN relies, among other things, on the correction of the calibration parameter from ...variations due to crystal ageing. This ageing will be measured by a so-called monitoring system, but the relation between monitoring and calibration parameter variations is not so trivial, and depends much on the overall optical characteristics of crystal and photodetector. We present here simulations done with the program Litrani based on real ageing data for a realistic CMS crystal with a defined surface quality (optically polished, with or without one lateral face slightly depolished), covered by coatings of various characteristics, from totally absorbing to nominal aluminum or diffusing medium. The correlation coefficient between monitoring and scintillation signals depends greatly on these characteristics, and varies between about 1.3 and more than 10 (the optimum being one).
Environmental tests of the GLAST validation module calorimeter Ferreira, O.; Bogaert, G.; Bonnemaison, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2004, Letnik:
530, Številka:
3
Journal Article
Recenzirano
This paper describes the results of vibration tests using the Validation Module of the GLAST Gamma Large Area Telescope calorimeter structure. The composite structure has been tested with different ...vibration spectra expected during the launch environment of GLAST. No degradation of the mechanical assembly was observed, and deformations and displacements stayed within stay-clear limits.
Performances of the CsI(Tl) detector element of the GLAST calorimeter Bédérède, D.; Bougamont, E.; Bourgeois, Ph ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2004, Letnik:
518, Številka:
1
Journal Article
Recenzirano
The CsI(Tl) Detector Element (CDE) is the unit of detection of the calorimeter subsystem of the Large Area Telescope (LAT) of the GLAST satellite (IEEE Nuclear Science Symposium, 2002), which will be ...launched in September 2006. The LAT consists of 4×4 identical towers, each one including a strip silicon tracker on the top and a CsI(Tl) calorimeter on the bottom. A segmented plastic scintillator anticoincidence detector surrounds the 16 towers. The calorimeter modules, 8 layers of 12 CDEs each, have a hodoscope's shape to allow the measurement of the gamma-ray direction.
The CDE main characteristics are its Light Yield, the energy resolution and the tapering, ratio of left/right signals used for the determination of the crossing position of the particle in the crystal.
The CDE have to operate in space at about −10°C. We will describe the CDE, the optimization of its main parameter, the L.Y., and finally its variation with temperature.
The amplitude of the signal collected from the PbWO4 crystals of the CMS electromagnetic calorimeter is reconstructed by a digital filtering technique. The amplitude reconstruction has been studied ...with test beam data recorded from a fully equipped barrel supermodule. Issues specific to data taken in the test beam are investigated, and the implementation of the method for CMS data taking is discussed.
A search for pair-production of first generation scalar leptoquarks is performed in the final state containing an electron, a neutrino, and at least two jets using proton-proton collision data at ...inline image. The data were collected by the CMS detector at the LHC, corresponding to an integrated luminosity of 36 pb super(-1. The number of observed events is in good agreement with the predictions for standard model processes. Prior CMS results in the dielectron channel are combined with this electron + neutrino search. A 95% confidence level combined lower limit is set on the mass of a first generation scalar leptoquark at 339 GeV for beta=0.5, where beta is the branching fraction of the leptoquark to an electron and a quark. These results represent the most stringent direct limits to date for values of beta greater than 0.05.)
The OPAL detector at LEP
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/1991
Journal Article
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