Overview of the 63000 PWO Barrel Crystals for CMS_ECAL Production

Auffray, E.

doi:10.1109/tns.2007.913935

Cited by 13 publications

(9 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Another difference between data and simulation, relevant to electron-photon differences, is the modelling of the varying fraction of scintillation light reaching the photodetector as a function of the longitudinal depth in the crystal at which it was emitted. Ensuring adequate uniformity was a major accomplishment in the lead tungstate crystal development that was achieved by depolishing one face of each barrel crystal, but an uncertainty in the degree of uniformity achieved remains [86,87]. In addition, the uniformity is modified by the radiation-induced loss of transparency of the crystals.…”

Section: Statistical Methodologymentioning

confidence: 99%

Observation of the diphoton decay of the Higgs boson and measurement of its properties

et al. 2014

View full text Add to dashboard Cite

Observation of the diphoton decay mode of the recently discovered Higgs boson and measurement of some of its properties are reported. The analysis uses the entire dataset collected by the CMS experiment in proton-proton collisions during the 2011 and 2012 LHC running periods. The data samples correspond to integrated luminosities of 5.1at and 19.7at 8 . A clear signal is observed in the diphoton channel at a mass close to 125 with a local significance of , where a significance of is expected for the standard model Higgs boson. The mass is measured to be , and the best-fit signal strength relative to the standard model prediction is . Additional measurements include the signal strength modifiers associated with different production mechanisms, and hypothesis tests between spin-0 and spin-2 models.

show abstract

Section: Statistical Methodologymentioning

confidence: 99%

Observation of the diphoton decay of the Higgs boson and measurement of its properties

et al. 2014

View full text Add to dashboard Cite

show abstract

“…The quality is excellent with most of the performance well above the specification value, as a result of a strict quality control procedure [4]. This is illustrated on Fig.…”

Section: A Crystalsmentioning

confidence: 85%

The CMS Calorimeter in 2007: Performance and Physics Goals

Lecoq

2008

IEEE Trans. Nucl. Sci.

View full text Add to dashboard Cite

Abstract-Thirteen years after the decision to build a Lead Tungstate based electromagnetic calorimeter for the CMS experiment at the Large Hadron Collider (LHC) at CERN the detector is now in its final assembly and installation phase for the LHC startup in early 2008. It is made of 75848 Lead Tungstate crystals, 61200 of 133 cubic centimeter for the barrel and 14648 of 189 cubic centimeter for the endcaps, for a total weight of 90 tons of crystals. This challenging project aims to achieve an extreme precision in photons and electrons energy measurement. General motivations, main technical challenges, measured performances, and the actual status of the project will be discussed.

show abstract

“…To simulate nonuniformity of light collection, an appropriate slope is introduced based on laboratory light-collection efficiency measurements made on the crystals, and measurements of its dependence on crystal transparency. The slope of the light collection efficiency as a function of depth, at the time when the ECAL was constructed, is taken to be −0.14 ± 0.08%/X 0 [29,30], for the front half of the crystal ("front nonuniformity"). The change of this slope, ∆F, is parametrized as a function of the absorption coef-ficient induced by irradiation measured in m −1 , ∆µ, and is given by ∆F = 0.4% × ∆µ/X 0 [31].…”

Section: Energy Scale Uncertaintymentioning

confidence: 99%

Performance of photon reconstruction and identification with the CMS detector in proton-proton collisions at √s= 8 TeV

Khachatryan¹,

Sirunyan²,

Tumasyan³

et al. 2015

J. Inst.

210

250

View full text Add to dashboard Cite

A description is provided of the performance of the CMS detector for photon reconstruction and identification in proton-proton collisions at a centre-of-mass energy of 8 TeV at the CERN LHC. Details are given on the reconstruction of photons from energy deposits in the electromagnetic calorimeter (ECAL) and the extraction of photon energy estimates. The reconstruction of electron tracks from photons that convert to electrons in the CMS tracker is also described, as is the optimization of the photon energy reconstruction and its accurate modelling in simulation, in the analysis of the Higgs boson decay into two photons. In the barrel section of the ECAL, an energy resolution of about 1% is achieved for unconverted or late-converting photons from H → γγ decays. Different photon identification methods are discussed and their corresponding selection efficiencies in data are compared with those found in simulated events.The central feature of the CMS apparatus is a superconducting solenoid of 6 m internal diameter, providing a magnetic field of 3.8 T. Within the superconducting solenoid volume are a silicon pixel and strip tracker, a lead tungstate crystal electromagnetic calorimeter, and a brass/scintillator hadron calorimeter (HCAL), each one composed of a barrel and two endcap sections. Muons are measured in gas-ionization detectors embedded in the steel flux-return yoke outside the solenoid. Extensive forward calorimetry complements the coverage provided by the barrel and endcap detectors. A more detailed description of the CMS detector can be found in Ref. [1].The pseudorapidity coordinates, η, of detector elements are measured with respect to the coordinate system origin at the centre of the detector, whereas the pseudorapidity of reconstructed particles and jets is measured with respect to the interaction vertex from which they originate. Photon reconstruction Photon reconstructionPhotons for use as signals or signatures in measurements and searches, rather than for use in the construction of jets or missing transverse energy, are reconstructed from energy deposits in the ECAL using algorithms that constrain the clusters to the size and shape expected for electrons and photons with p T 15 GeV. The algorithms do not use any hypothesis as to whether the particle originating from the interaction point is a photon or an electron, consequently electrons from Z → e + e − events, for which pure samples with a well defined invariant mass can be selected, can provide excellent measurements of the photon trigger, reconstruction, and identification efficiencies, and of the photon energy scale and resolution. The reconstructed showers are generally limited to a fiducial region excluding the last two crystals at each end of the barrel (|η| < 1.4442). The outer circumferences of the endcaps are obscured by services passing between the barrel and the endcaps, and this area is removed from the fiducial region by excluding the first ring of trigger towers of the endcaps (|η| > 1.566). The fiducial region terminates at |η| = 2.5...

show abstract

Overview of the 63000 PWO Barrel Crystals for CMS_ECAL Production

Cited by 13 publications

References 10 publications

Observation of the diphoton decay of the Higgs boson and measurement of its properties

Observation of the diphoton decay of the Higgs boson and measurement of its properties

The CMS Calorimeter in 2007: Performance and Physics Goals

Performance of photon reconstruction and identification with the CMS detector in proton-proton collisions at √s= 8 TeV

Contact Info

Product

Resources

About