Simulation of light collection in the CMS lead tungstate crystals with the program Litrani: coating and surface effects

Chipaux, R.; Gentit, F. X.

doi:10.1016/s0168-9002(02)00673-3

Cited by 8 publications

(3 citation statements)

References 10 publications

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“…I have also used it for the GLAST [5] experiment. Inside CMS, Litrani has also been used by Rémi Chipaux [6] and by J.P.Peigneux [7]. Having put the program on the web, other users all around the world have used it as well.…”

Section: Applications Using Litranimentioning

confidence: 99%

Litrani: a general purpose Monte-Carlo program simulating light propagation in isotropic or anisotropic media

Gentit

2002

Nuclear Instruments and Methods in Physics Research Section A:

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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 2 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.

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Section: Applications Using Litranimentioning

confidence: 99%

Litrani: a general purpose Monte-Carlo program simulating light propagation in isotropic or anisotropic media

Gentit

2002

Nuclear Instruments and Methods in Physics Research Section A:

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“…Such values are consistent with each other since the former represents the intrinsic absorption coefficient of a non-irradiated crystal whereas the latter also takes into account for the larger average path of isotropic light and surface effects. For such good light transmittance, the light collection efficiency of a non irradiated crystal is influenced by a "focusing" effect due to the tapered geometry [17]. This effect enhances the collection efficiency at the rear photodetector for photons produced close to the front crystal face.…”

Section: Comparison With Simulationmentioning

confidence: 99%

Double side read-out technique for mitigation of radiation damage effects in PbWO₄crystals

et al. 2016

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Test beam results of a calorimetric module based on 3×3×22 cm3 PbWO4 crystals, identical to those used in the CMS ECAL Endcaps, read out by a pair of photodetectors coupled to the two opposite sides (front and rear) of each crystal are presented. Nine crystals with different level of induced absorption, from 0 to 20 m−1, have been tested using electrons in the 50–200 GeV energy range. Photomultiplier tubes have been chosen as photodetectors to allow for a precise measurement of highly damaged crystals. The information provided by this double side read-out configuration allows to correct for event-by-event fluctuations of the longitudinal development of electromagnetic showers. By strongly mitigating the effect of non-uniform light collection efficiency induced by radiation damage, the double side read-out technique significantly improves the energy resolution with respect to a single side read-out configuration. The non-linearity of the response arising in damaged crystals is also corrected by a double side read-out configuration and the response linearity of irradiated crystals is restored. In high radiation environments at future colliders, as it will be the case for detectors operating during the High Luminosity phase of the Large Hadron Collider, defects can be created inside the scintillator volume leading to a non-uniform response of the calorimetric cell. The double side read-out technique presented in this study provides a valuable way to improve the performance of calorimeters based on scintillators whose active volumes are characterized by high aspect ratio cells similar to those used in this study.

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“…Previous papers [2]- [4] have shown that, in general, the correlation between variations of collection efficiencies for scintillation light (directly related to the calibration parameters) and monitoring light is dominated, for crystals of good optical quality, by the quality of light containment in crystals, defined by the properties of their surfaces and coating. The properties of the readout device are also important: surface, optical coupling, quantum efficiency versus wavelength, etc.…”

Section: Introductionmentioning

confidence: 99%

Transparency Variations and Calibration in CMS Electromagnetic Calorimeter Crystals: Monte Carlo Studies

Chipaux

Gentit

2010

IEEE Trans. Nucl. Sci.

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The aging of CMS electronic calorimeter scintillating crystals under radiation leads to a deterioration of their transparency, and thus of their effective light yield and their calibration. The correlation between transparency variation, as measured by the fiber-optic monitoring system, and the calibration variation depends on the optical properties of the scintillating material itself and of its environment. In previous studies, the possibility of light scattering within the bulk of the crystals was not taken into account.We present here the results of the simulation of this correlation for different types of CMS electronic calorimeter crystals using the program Litrani improved to allow light scattering in bulk. They show that scattering could explain the variation of correlation coefficients observed between CMS/ECAL endcap and barrel crystals.

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Simulation of light collection in the CMS lead tungstate crystals with the program Litrani: coating and surface effects

Cited by 8 publications

References 10 publications

Litrani: a general purpose Monte-Carlo program simulating light propagation in isotropic or anisotropic media

Litrani: a general purpose Monte-Carlo program simulating light propagation in isotropic or anisotropic media

Double side read-out technique for mitigation of radiation damage effects in PbWO₄crystals

Transparency Variations and Calibration in CMS Electromagnetic Calorimeter Crystals: Monte Carlo Studies

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Simulation of light collection in the CMS lead tungstate crystals with the program Litrani: coating and surface effects

Cited by 8 publications

References 10 publications

Litrani: a general purpose Monte-Carlo program simulating light propagation in isotropic or anisotropic media

Litrani: a general purpose Monte-Carlo program simulating light propagation in isotropic or anisotropic media

Double side read-out technique for mitigation of radiation damage effects in PbWO4crystals

Transparency Variations and Calibration in CMS Electromagnetic Calorimeter Crystals: Monte Carlo Studies

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Product

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Double side read-out technique for mitigation of radiation damage effects in PbWO₄crystals