Time reconstruction and performance of the CMS electromagnetic calorimeter

Collaboration, CMS

doi:10.1088/1748-0221/5/03/t03011

Cited by 46 publications

(28 citation statements)

References 8 publications

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“…The fast time constants of PbWO 4 scintillation and the response of the readout electronics provide excellent time resolution capabilities [8]. The signal arrival time is measured from the relative phase of the signal samples to the expected shape of an in-time signal, with an algorithm using ratios of consecutive samples.…”

Section: Reconstruction and Energy Calibrationmentioning

confidence: 99%

Energy calibration and resolution of the CMS electromagnetic calorimeter in pp collisions at √s= 7 TeV

Chatrchyan¹,

Khachatryan²,

Sirunyan³

et al. 2013

J. Inst.

171

155

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The energy calibration and resolution of the electromagnetic calorimeter (ECAL) of the CMS detector have been determined using proton-proton collision data from LHC operation in 2010 and 2011 at a centre-of-mass energy of √ s = 7 TeV with integrated luminosities of about 5 fb −1 . Crucial aspects of detector operation, such as the environmental stability, alignment, and synchronization, are presented. The in-situ calibration procedures are discussed in detail and include the maintenance of the calibration in the challenging radiation environment inside the CMS detector. The energy resolution for electrons from Z-boson decays is better than 2% in the central region of the ECAL barrel (for pseudorapidity |η| < 0.8) and is 2-5% elsewhere. The derived energy resolution for photons from 125 GeV Higgs boson decays varies across the barrel from 1.1% to 2.6% and from 2.2% to 5% in the endcaps. The calibration of the absolute energy is determined from Z → e + e − decays to a precision of 0.4% in the barrel and 0.8% in the endcaps.

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Section: Reconstruction and Energy Calibrationmentioning

confidence: 99%

Energy calibration and resolution of the CMS electromagnetic calorimeter in pp collisions at √s= 7 TeV

Chatrchyan¹,

Khachatryan²,

Sirunyan³

et al. 2013

J. Inst.

171

155

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“…[15]. Topological and timing criteria suppress noise present in the ECAL [14,16].We reconstruct two photons using the selection described above and require that the invariant mass of the two photons satisfies M γγ > 60 GeV. The invariant mass and photon pseudorapidity selection criteria are optimized to produce the highest sensitivity for values of M S and n ED to which the present data is sensitive.…”

mentioning

confidence: 99%

Search for large extra dimensions in the diphoton final state at the Large Hadron Collider

Quertenmont¹,

Chatrchyan

Başeğmez

et al. 2011

J. High Energ. Phys.

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Abstract:A search for large extra spatial dimensions via virtual-graviton exchange in the diphoton channel has been carried out with the CMS detector at the LHC. No excess of events above the standard model expectations is found using a data sample collected in proton-proton collisions at √ s = 7 TeV and corresponding to an integrated luminosity of 36 pb −1 . New lower limits on the effective Planck scale in the range of 1.6-2.3 TeV at the 95% confidence level are set, providing the most restrictive bounds to date on models with more than two large extra dimensions. Keywords: Hadron-Hadron ScatteringOpen IntroductionCompact large extra dimensions (ED) are an intriguing proposed solution to the hierarchy problem of the standard model (SM), which refers to the puzzling fact that the fundamental scale of gravity M Pl ∼ 10 19 GeV is so much higher than the electroweak symmetry breaking scale ∼ 10 3 GeV. With such a difference in scales, it is difficult to protect the Higgs boson mass from radiative corrections without a very high degree of fine-tuning. The original proposal to use ED to solve the hierarchy problem was presented by ArkaniHamed, Dimopoulos, and Dvali (ADD) [1,2]. They posited a scenario wherein the SM is constrained to the common 3+1 space-time dimensions, while gravity is free to propagate through the entire multidimensional space. Thus, the gravitational flux in 3+1 dimensions is effectively diluted by virtue of the multidimensional Gauss's Law. The fundamental Planck scale M D is therefore related to the apparent scale M Pl according to the formula M n ED +2 D = M 2 Pl /r n ED , where r and n ED are the size and number of the extra dimensions, respectively. A review of current limits on the ADD model can be found in ref. [3].Phenomenologically, this large ED scenario results in s-channel production of massive, virtual Kaluza-Klein (KK) graviton states, which can decay into two photons [4]. Decays to fermions are suppressed relative to photons because the graviton is spin-2 and the fermions cannot be produced in the s wave. Because the KK gravitons propagate through the compact extra dimensions, their wavefunction must satisfy periodic boundary conditions, which result in discrete energy levels with modal spacing of the order of the inverse ED size, from 1 meV to 100 MeV. This results in an apparent continuum spectrum of diphotons, rather than distinct resonances.Summing over KK modes results in a divergence in the cross section, so an ultraviolet (UV) cutoff scale M S is needed. This scale is related to -but potentially different fromthe fundamental Planck scale M D , as the precise relationship depends on the UV completion of the effective theory. The effects of virtual-graviton production on the cross section are -1 - JHEP05(2011)085parameterized by the single variable η G = F/M 4 S , where F is an order-unity dimensionless parameter, for which several conventional assumptions exist: where √ŝ is the center-of-mass energy of the hard parton-parton collision. We note that the HLZ convention contai...

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“…Fig. 2 [9] shows an example ECAL pulse shape with the 10 digitized samples. The readout phase is adjusted such that the signal peaks on the sixth sample and the first three samples are used to measure the pedestal.…”

Section: Ecal Timing Performancementioning

confidence: 99%

Prospects for a precision timing upgrade of the CMS PbWO4 crystal electromagnetic calorimeter for the HL-LHC

Marzocchi

2020

Nuclear Instruments and Methods in Physics Research Section A:

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The upgrade of the Compact Muon Solenoid (CMS) crystal electromagnetic calorimeter (ECAL), which will operate at the High Luminosity Large Hadron Collider (HL-LHC), will achieve a timing resolution of around 30 ps for high energy photons and electrons. In this talk we will discuss the benefits of precision timing for the ECAL event reconstruction at HL-LHC. Simulation studies on the timing properties of PbWO crystals, as well as the impact of the photosensors and the readout electronics on the timing performance, will be presented. Test beam studies on the timing performance of PbWO crystals with various photosensors and readout electronics will be shown. AbstractThe upgrade of the Compact Muon Solenoid (CMS) crystal electromagnetic calorimeter (ECAL), which will operate at the High Luminosity Large Hadron Collider (HL-LHC), will achieve a timing resolution of around 30 ps for high energy photons and electrons. In this talk we will discuss the benefits of precision timing for the ECAL event reconstruction at HL-LHC. Simulation studies on the timing properties of PbWO crystals, as well as the impact of the photosensors and the readout electronics on the timing performance, will be presented. Test beam studies on the timing performance of PbWO 4 crystals with various photosensors and readout electronics will be shown.

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Time reconstruction and performance of the CMS electromagnetic calorimeter

Cited by 46 publications

References 8 publications

Energy calibration and resolution of the CMS electromagnetic calorimeter in pp collisions at √s= 7 TeV

Energy calibration and resolution of the CMS electromagnetic calorimeter in pp collisions at √s= 7 TeV

Search for large extra dimensions in the diphoton final state at the Large Hadron Collider

Prospects for a precision timing upgrade of the CMS PbWO4 crystal electromagnetic calorimeter for the HL-LHC

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