-- AminaZghiche - 2019-10-18

CMS-DP-2019/038

CMS ECAL Performance for Ultra Legacy re-reconstruction of 2018 and run 2 Preshower plots

Abstract: CMS ECAL , calibration and performance in 2018 ultra legacy re-reconstruction.

CDS entry

iCMS entry


Figure Caption

pdf version

pi0MassEBxtal index 30003.png

pdf version

pi0MassEExtal index 8155.png

Examples of the invariant mass of photon pairs with one photon depositing a fraction of its energy in a crystal of the ECAL Barrel at η = -0.03 (top), and of the ECAL Endcap at η = 1.83 (bottom), in the mass range of the π0.

A subset of the data collected in 2018 is used, corresponding to half of the total dataset. These events are collected by CMS with a dedicated trigger at a rate of 7 (2) kHz in the Barrel (Endcaps). The high trigger rate is made possible by a special clustering algorithm that saves only a minimal amount of information of the events, in particular, energy deposits in the ECAL crystals surrounding a possible π0 candidate. For candidates in the Endcaps, the determination of the photon position in the region with 1.7 <abs(η)< 2.55 is improved by the presence of the Preshower, which results in a better mass resolution.

These events are used as prompt feedback to monitor the effectiveness of the laser monitoring calibration and to inter-calibrate the energy of ECAL crystals. The π0 mass is shown before the crystal inter-calibration.

pdf version

medianmeevstimeinEB v2.png

pdf version

medianmeevstimeinEE v2.png

Time stability of the di-electron invariant mass distribution for the 2018 data taking period

using Z→ee electrons.

The plot shows the time stability of the median di-electron invariant mass with a refined

re-calibration performed in 2019 for the full 2018 dataset. Both electrons are required to be

in the ECAL Barrel (left) or in the ECAL Endcaps (right). Each time bin has around 10,000 events.

The error bar on the points denotes the statistical uncertainty on the median, which is

evaluated as the central 95% interval of medians obtained from 200 "bootstrap" re-samplings.

The right panel shows the distribution of the medians.

At the analysis level, residual drifts in the energy scale with time are corrected for

in approximately 18-hour intervals corresponding to at most one LHC fill.

pdf version

medianR9eLvstimeinEB v2.png

pdf version

medianR9eLvstimeinEE v2.png

Stability of the shower shape of the electromagnetic deposits in the ECAL for leading

electrons from Z decays.

The plot shows the time stability of the shower shape of the leading electron from Z decays

with a refined re-calibration performed in 2019. The event selection requires two electrons to be

in the ECAL Barrel (left) or in the ECAL Endcaps (right). Each time bin has around 10,000 events.

The error bar on the points denotes the statistical uncertainty on the median, which is

evaluated as the central 95% interval of medians obtained from 200 "bootstrap" re-samplings.

The right panel shows the distribution of the medians. The shower shape is measured

by the variable R9, defined as the ratio of the energy deposit in the 3x3 crystal matrix around

the seed crystal to that in the supercluster. R9 is responsive to changes in pedestal and noise.

pdf version

mee in EB fixedWidthNoFitLine.png

pdf version

mee in EE fixedWidthNoFitLine.png

Di-electron invariant mass distribution for the 2018 data taking period using Z→ee electrons.

The plot shows the di-electron invariant mass distribution for Z decay events with two calibration sets for the full 2018 dataset: the “preliminary” autumn 2018 calibration (RED) and a “refined” re-calibration performed in 2019 (GREEN). While for the refined calibration a complete re-calibration of the crystals was performed, for the preliminary calibration only time-dependent effects for the first part of the dataset were accounted for.

Both electrons are required to be in the ECAL Barrel (left) or in the ECAL Endcaps (right). The relative resolutions are quoted in the legend, defined as the ratio of σ (Gaussian standard deviation of the Gaussian that is convoluted with a Breit-Wigner as the signal model (Voigtian fit)) to μ (mean). Events used in the calibration are excluded from the fit.

pdf version

mee in EB HighR9 fixedWidthNoFitLine.png

pdf version

mee in EE HighR9 fixedWidthNoFitLine.png

Di-electron invariant mass distribution for the 2018 data taking period using

Z→ee low-bremsstrahlung electrons.

The plot shows the di-electron invariant mass distribution for Z decay events with two calibration sets for the full 2018 dataset: the “preliminary” autumn 2018 calibration (RED) and a “refined” re-calibration performed in 2019 (GREEN). While for the refined calibration a complete re-calibration of the crystals was performed, for the preliminary calibration only time-dependent effects for the first part of the dataset were accounted for.

Both electrons are required to be in the ECAL Barrel (left) or in the ECAL Endcaps (right) and to have low bremsstrahlung. The relative resolutions are quoted in the legend, defined as the ratio of σ (Gaussian standard deviation of the Gaussian that is convoluted with a Breit-Wigner as the signal model (Voigtian fit)) to μ (mean). Events used in the calibration are excluded from the fit.

Refined calibration fitted resolution values (1.4% and 2.7% for EB and EE, respectively)are consistent with those obtained in the final SuperCluster unfolded resolution results (~2%(/sqrt(2)) and ~4%(/sqrt(2)) for EB and EE, respectively.)

pdf version

mee in EB LowR9 fixedWidthNoFitLine.png

pdf version

mee in EE LowR9 fixedWidthNoFitLine.png

Di-electron invariant mass distribution for the 2018 data taking period using

Z→ee high-bremsstrahlung electrons.

The plot shows the di-electron invariant mass distribution for Z decay events with two calibration sets for the full 2018 dataset: the “preliminary” autumn 2018 calibration (RED) and a “refined” re-calibration performed in 2019 (GREEN). While for the refined calibration a complete re-calibration of the crystals was performed, for the preliminary calibration only time-dependent effects for the first part of the dataset were accounted for.

Both electrons are required to be in the ECAL Barrel (left) or in the ECAL Endcaps (right) and to have high bremsstrahlung. The relative resolutions are quoted in the legend, defined as the ratio of σ (Gaussian standard deviation of the Gaussian that is convoluted with a Breit-Wigner as the signal model (Voigtian fit)) to μ (mean). Events used in the calibration are excluded from the fit.

pdf version

Resolution 2018 lowBremsstrahlung v2.png

pdf version

Resolution 2018 inclusive v2.png

ECAL energy resolution with Zee in 2018 data

Relative electron (ECAL) energy resolution unfolded in bins of pseudo-rapidity η for the ECAL Barrel and the ECAL Endcaps. Electrons from Z→ee decays are used. The resolution is shown separately for low bremsstrahlung electrons and for all electrons (“inclusive”). The resolution is measured on 2018 data. The relative resolution σE/E is extracted from an unbinned likelihood fit to Z→ee events, using a Voigtian (Breit-Wigner convoluted with Gaussian) as the signal model.

Conclusions:

• The resolution is affected by the amount of material in front of the ECAL and is degraded in the vicinity of the eta cracks between ECAL modules (indicated by the vertical lines in the plot)

• The last point of the preliminary calibration is out of the y-axis scale of the plot

• The resolution improves significantly after a refined calibration using the full 2018 dataset with respect to a preliminary calibration for which only time dependent effects in the first part of the dataset were corrected for

pdf version
Intercalibration precision v2.png

2018 inter-calibration precision

Residual mis-calibration of the ECAL channel inter-calibration, as a function of pseudo-rapidity with the dataset recorded during 2018. The red, blue, and green points represent the residual mis-calibration of the intercalibration constants (IC) obtained with three different methods, and the black points represent the residual mis-calibration of the combination of the three methods. The red points refer to the IC obtained with electrons from Z→ee decays using the known Z mass as energy reference. The blue points refer to IC obtained with electrons from W and Z decays using the tracker momentum as energy reference. The green points refer to IC obtained using photons from π0→γγ decays. Such decays are used only for abs(η)<2 due to the low signal over noise ratio otherwise. The IC combination is performed by weighting the different methods relatively to energy resolution performance as measured in Z→ee decays. Between 2<abs(η)<2.5, the E/p point used for combination is out of the y-axis scale of the plot. No combination is performed for abs(η)>2.5, where only Z→ee decays are used.

pdf version
DegradeByLumi 2015Bto2018D4 Front v2.png

The two planes of the Preshower (ES), coupled with the EE crystals, form a sampling calorimeter. The ES essentially counts the number of charged particles passing through the layers of silicon, which is an estimate of the amount of energy deposited in the ES lead absorbers. We use charged particles with momentum nearly close to minimum ionizing to calibrate the ES, so for simplicity we refer to them as “MIPs”. They are collected with the Preshower operated in high-gain mode. The design-goal accuracy of the channel-by-channel calibration is set to 5%. This corresponds to a contribution of about 0.25% to the overall EE+ES energy resolution for high-energy electrons since only a few percent of electron/photon energy is deposited in ES. The sources of response variation (sensor-to-sensor and channel-to-channel) are the sensor thickness seen by the incident particles (depends on angle of incidence), gain of the front-end electronics chain, and charge collection efficiency which varies with the radiation damage.

The plot shows the decreasing of MIP response with regard to the 2015 calibration (from 2015B to the end of 2018D) in 5 eta regions (the interval in eta is 0.2) of the front plane. The x-coordinate of each data point represents the integrated luminosity at which the MIP calibration was done. The calibration was performed every 10-20 fb-1.

The decreasing rate on ES+ is similar to one on ES-, thus the averages of those rates are used.

In general, the MIP responses decrease as a function of luminosity. The only exception is in the beginning of 2017 data taking, when the bias voltage was increased by 80 Volts

The MIP response decreases faster in the higher eta region. This result implies that the ES sensors in high eta regions are more affected by the radiation damage.

pdf version
DegradeByLumi 2015Bto2018D4 Rear v2.png

The plot shows the decreasing of MIP response with regard to the 2015 calibration (from 2015B to the end of 2018D) in 5 eta regions (the interval in eta is 0.2) of the rear plane. The x-coordinate of each data point represents the integrated luminosity at which the MIP calibration was done. The calibration was performed every 10-20 fb-1.

The decreasing rate on ES+ is similar to one on ES-, thus the averages of those rates are used.

In general, the MIP responses decrease as a function of luminosity. The only exception is in the beginning of 2017 data taking, when the bias voltage was increased by 80 Volts

The MIP response decreases faster in the higher eta region. This result implies that the ES sensors in high eta regions are more affected by the radiation damage

pdf version
EnergyByRun Conference v2.png

Due to radiation damage, the Preshower response decreases with time. A data/MC correction on the runs between 2 successive calibrations to stabilize the recorded energy is applied. The correction was computed by minimizing the χ2 value between the energy distribution of data and MC.

The plot shows the calibrated deposited energy of electrons measured with the Preshower planes at low gain as a function of integrated luminosity before (BLACK) and after (BLUE) applying the correction factor. It also displays the comparison to the MC prediction (RED).

Four different data/MC correction factors are applied in this plot. They are calculated for sub-periods in a period between two consecutive high gain calibrations of an integrated luminosity of 9.7 fb-1. The 4 sub-periods are separated with vertical lines (GREEN).

The High gain calibration, normalized to low gain by a factor of 1/6, is applied to the data points in black. Then for each sub-period, a data/MC correction factor is derived and applied at the middle of the interval, generating a slight over correction in the beginning of the intervals.

Applying the data/MC correction to the data between two ES calibrations, improves the stability of the energy measurement.

Topic attachments
I Attachment History Action Size Date Who CommentSorted ascending
PDFpdf DegradeByLumi_2015Bto2018D4_Front.pdf r1 manage 17.9 K 2019-10-21 - 16:09 AminaZghiche ES plots
PNGpng DegradeByLumi_2015Bto2018D4_Front.png r1 manage 46.1 K 2019-10-21 - 16:09 AminaZghiche ES plots
PDFpdf DegradeByLumi_2015Bto2018D4_Rear.pdf r1 manage 18.0 K 2019-10-21 - 16:09 AminaZghiche ES plots
PNGpng DegradeByLumi_2015Bto2018D4_Rear.png r1 manage 46.0 K 2019-10-21 - 16:09 AminaZghiche ES plots
PDFpdf EnergyByRun_Conference.pdf r1 manage 27.2 K 2019-10-21 - 16:09 AminaZghiche ES plots
PNGpng EnergyByRun_Conference.png r1 manage 77.4 K 2019-10-21 - 16:09 AminaZghiche ES plots
PNGpng Intercalibration_precision.png r1 manage 42.4 K 2019-10-21 - 16:42 AminaZghiche intercalibration precision
PDFpdf medianmeevstimeinEB.pdf r1 manage 188.2 K 2019-10-21 - 16:42 AminaZghiche intercalibration precision
PDFpdf mee_in_EB_HighR9_fixedWidthNoFitLine.pdf r1 manage 21.6 K 2019-10-21 - 16:37 AminaZghiche invariant mass
PNGpng mee_in_EB_HighR9_fixedWidthNoFitLine.png r1 manage 87.7 K 2019-10-21 - 16:37 AminaZghiche invariant mass
PDFpdf mee_in_EB_LowR9_fixedWidthNoFitLine.pdf r1 manage 21.5 K 2019-10-21 - 16:37 AminaZghiche invariant mass
PNGpng mee_in_EB_LowR9_fixedWidthNoFitLine.png r1 manage 88.7 K 2019-10-21 - 16:37 AminaZghiche invariant mass
PDFpdf mee_in_EB_fixedWidthNoFitLine.pdf r1 manage 21.5 K 2019-10-21 - 16:37 AminaZghiche invariant mass
PNGpng mee_in_EB_fixedWidthNoFitLine.png r1 manage 84.0 K 2019-10-21 - 16:37 AminaZghiche invariant mass
PDFpdf mee_in_EE_HighR9_fixedWidthNoFitLine.pdf r1 manage 22.0 K 2019-10-21 - 16:37 AminaZghiche invariant mass
PNGpng mee_in_EE_HighR9_fixedWidthNoFitLine.png r1 manage 95.7 K 2019-10-21 - 16:37 AminaZghiche invariant mass
PDFpdf mee_in_EE_LowR9_fixedWidthNoFitLine.pdf r1 manage 22.3 K 2019-10-21 - 16:38 AminaZghiche invariant mass
PNGpng mee_in_EE_LowR9_fixedWidthNoFitLine.png r1 manage 95.8 K 2019-10-21 - 16:38 AminaZghiche invariant mass
PDFpdf mee_in_EE_fixedWidthNoFitLine.pdf r1 manage 21.6 K 2019-10-21 - 16:37 AminaZghiche invariant mass
PNGpng mee_in_EE_fixedWidthNoFitLine.png r1 manage 89.6 K 2019-10-21 - 16:37 AminaZghiche invariant mass
PNGpng Intercalibration_precision_v2.png r1 manage 97.7 K 2019-10-29 - 14:28 AminaZghiche  
PDFpdf pi0MassEBxtal_index_30003.pdf r1 manage 19.0 K 2019-10-21 - 16:08 AminaZghiche pi0
PNGpng pi0MassEBxtal_index_30003.png r1 manage 28.6 K 2019-10-21 - 16:08 AminaZghiche pi0
PDFpdf pi0MassEExtal_index_8155.pdf r1 manage 18.8 K 2019-10-21 - 16:08 AminaZghiche pi0
PNGpng pi0MassEExtal_index_8155.png r1 manage 26.5 K 2019-10-21 - 16:08 AminaZghiche pi0
PDFpdf Resolution_2018_inclusive.pdf r1 manage 36.7 K 2019-10-21 - 16:33 AminaZghiche Resolution
PNGpng Resolution_2018_inclusive.png r1 manage 20.0 K 2019-10-21 - 16:34 AminaZghiche resolution
PDFpdf Resolution_2018_lowBremsstrahlung.pdf r1 manage 37.3 K 2019-10-21 - 16:33 AminaZghiche Resolution
PNGpng Resolution_2018_lowBremsstrahlung.png r1 manage 21.2 K 2019-10-21 - 16:34 AminaZghiche resolution
PDFpdf medianR9eLvstimeinEB.pdf r1 manage 183.8 K 2019-10-21 - 16:36 AminaZghiche stability
PNGpng medianR9eLvstimeinEB.png r1 manage 90.7 K 2019-10-21 - 16:36 AminaZghiche stability
PDFpdf medianR9eLvstimeinEE.pdf r1 manage 47.5 K 2019-10-21 - 16:36 AminaZghiche stability
PNGpng medianR9eLvstimeinEE.png r1 manage 57.4 K 2019-10-21 - 16:36 AminaZghiche stability
PNGpng medianmeevstimeinEB.png r1 manage 110.8 K 2019-10-21 - 16:36 AminaZghiche stability
PDFpdf medianmeevstimeinEE.pdf r1 manage 49.6 K 2019-10-21 - 16:36 AminaZghiche stability
PNGpng medianmeevstimeinEE.png r1 manage 79.2 K 2019-10-21 - 16:36 AminaZghiche stability
PDFpdf DegradeByLumi_2015Bto2018D4_Front_v2.pdf r1 manage 18.2 K 2019-10-29 - 15:34 AminaZghiche version2 of ES plots
PNGpng DegradeByLumi_2015Bto2018D4_Front_v2.png r1 manage 48.2 K 2019-10-29 - 15:34 AminaZghiche version2 of ES plots
PDFpdf DegradeByLumi_2015Bto2018D4_Rear_v2.pdf r1 manage 18.2 K 2019-10-29 - 15:34 AminaZghiche version2 of ES plots
PNGpng DegradeByLumi_2015Bto2018D4_Rear_v2.png r1 manage 48.3 K 2019-10-29 - 15:34 AminaZghiche version2 of ES plots
PDFpdf EnergyByRun_Conference_v2.pdf r1 manage 27.9 K 2019-10-29 - 15:34 AminaZghiche version2 of ES plots
PNGpng EnergyByRun_Conference_v2.png r1 manage 98.9 K 2019-10-29 - 15:34 AminaZghiche version2 of ES plots
PDFpdf Resolution_2018_inclusive_v2.pdf r1 manage 16.2 K 2019-10-29 - 14:34 AminaZghiche version2 of resolution plots
PNGpng Resolution_2018_inclusive_v2.png r1 manage 19.1 K 2019-10-29 - 14:34 AminaZghiche version2 of resolution plots
PDFpdf Resolution_2018_lowBremsstrahlung_v2.pdf r1 manage 16.2 K 2019-10-29 - 14:34 AminaZghiche version2 of resolution plots
PNGpng Resolution_2018_lowBremsstrahlung_v2.png r1 manage 20.0 K 2019-10-29 - 14:34 AminaZghiche version2 of resolution plots
PDFpdf Intercalibration_precision_v2.pdf r1 manage 335.5 K 2019-10-29 - 14:26 AminaZghiche version2 Zee calibration
PDFpdf medianR9eLvstimeinEB_v2.pdf r1 manage 190.4 K 2019-10-29 - 14:26 AminaZghiche version2 Zee calibration
PNGpng medianR9eLvstimeinEB_v2.png r1 manage 61.5 K 2019-10-29 - 14:26 AminaZghiche version2 Zee calibration
PDFpdf medianR9eLvstimeinEE_v2.pdf r1 manage 48.4 K 2019-10-29 - 14:26 AminaZghiche version2 Zee calibration
PNGpng medianR9eLvstimeinEE_v2.png r1 manage 52.4 K 2019-10-29 - 14:26 AminaZghiche version2 Zee calibration
PDFpdf medianmeevstimeinEB_v2.pdf r1 manage 192.9 K 2019-10-29 - 14:26 AminaZghiche version2 Zee calibration
PNGpng medianmeevstimeinEB_v2.png r1 manage 95.6 K 2019-10-29 - 14:26 AminaZghiche version2 Zee calibration
PDFpdf medianmeevstimeinEE_v2.pdf r1 manage 50.2 K 2019-10-29 - 14:26 AminaZghiche version2 Zee calibration
PNGpng medianmeevstimeinEE_v2.png r1 manage 78.3 K 2019-10-29 - 14:26 AminaZghiche version2 Zee calibration
Edit | Attach | Watch | Print version | History: r8 < r7 < r6 < r5 < r4 | Backlinks | Raw View | WYSIWYG | More topic actions
Topic revision: r8 - 2019-11-12 - AminaZghiche
 
    • Cern Search Icon Cern Search
    • TWiki Search Icon TWiki Search
    • Google Search Icon Google Search

    CMSPublic All webs login

This site is powered by the TWiki collaboration platform Powered by PerlCopyright &© 2008-2021 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
or Ideas, requests, problems regarding TWiki? use Discourse or Send feedback