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Dielectron events in HF and Castor

Dielectron events in HF and Castor. Vardan Khachatryan ( AN S L , Armenia) Ekaterina Kuznetsova (DESY, Germany). CASTOR meeting 16 Nov 2011. Contents. J/ Ψ → e - e + , ϒ → e - e + Electron candidates reconstruction in HF 2010 data analysis Summary. J/ Ψ → ee Events.

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Dielectron events in HF and Castor

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  1. Dielectron events in HF and Castor Vardan Khachatryan (ANSL, Armenia) Ekaterina Kuznetsova (DESY, Germany) CASTOR meeting 16 Nov 2011

  2. Contents • J/Ψ→ e-e+, ϒ→ e-e+ • Electron candidates reconstruction in HF • 2010 data analysis • Summary CASTOR meeting, 16 Nov 2011

  3. J/Ψ→eeEvents For the event generation Pythia6 Cuts eHF : -3<η<-5 (HF) eCASTOR : -6.6<η<-5.3 (EM modules) Castor (combined with HF) sees 17k (2.1%) J/Ψ in generated 800k (expected ~2.5 M J/Ψ for 2010 data) CASTOR meeting, 16 Nov 2011

  4. ϒ→ee Events Castor (combined with HF) sees 1300 (0.43%) ϒ in generated 300k (expected 300k for 2010 data) CASTOR meeting, 16 Nov 2011

  5. J/Ψ→ee, ϒ→ee Events Pseudorapidity distribution for e–e+ originated from the J/psi (left) and Y (right) decays and detected with CASTOR and HF; generator level. CASTOR meeting, 16 Nov 2011

  6. J/Ψ→ee, ϒ→ee Events Invariant mass distribution for e–e+ originated from the J/psi (left) and Y (right) decays and detected with CASTOR and HF; generator level (HF resolution and CASTOR segmentation are taken into account). CASTOR meeting, 16 Nov 2011

  7. J/Ψ→ee, ϒ→ee Events J/Ψ→ee ϒ→ee CASTOR meeting, 16 Nov 2011

  8. Electron candidates reconstruction in HF To go to "low E" cut for HF we need to modify HF EGamma algorithm? In the standard algo. we have variable seedThresholdET = cms.double(5.0) seedThresholdET = cms.double(5.0) → replaced by 0.5 GeV New cut is used on the reconstructed object must be E > 30 GeV CASTOR meeting, 16 Nov 2011

  9. Electron candidates reconstruction in HF Electron reconstruction efficiency for new “seedThresholdET”, and energy thresholds. Twiki: https://twiki.cern.ch/twiki/bin/view/CMSPublic/SWGuideHFElectrons CASTOR meeting, 16 Nov 2011

  10. Electron candidates reconstruction in HF Reconstructed electron’s energy resolution for new “seedThresholdET”, and energy thresholds. CMS Note 2006/044 (E=50 GeV, resolution 29%) CASTOR meeting, 16 Nov 2011

  11. HF electron’s energy resolution CMS Note 2006/044 Single electron reconstruction in CMSSW_4_2_5. CASTOR meeting, 16 Nov 2011

  12. Electron candidates selection in the Castor • Cluster for electron candidates reconstruction: 2 (sector) x 3 (modules) • To find the claster: • Two neighbour sectors are selected (module=1, 2, 3) • Main energy deposition (>80%) must be in one sector in EM modules • Energy of modules 4 and 5 must be within the pedestal ranges (to be sure that we have electromagnetic shower). • Small energy in module 3. • Efficiency of this selection checked on MC reco : Eff>90% CASTOR meeting, 16 Nov 2011

  13. 2010 data analysis • For data analysis (in CMSSW_4_2_5) datasets were used: • /EG/Run2010A-Apr21ReReco-v1/RECO • /Mu/Run2010A-Apr21ReReco-v1/RECO • /Electron/Run2010B-Apr21ReReco-v1/RECO • /Mu/Run2010B-Apr21ReReco-v1/RECO • /MinimumBias/Run2010B-Apr21ReReco-v1/RECO • /MinimumBias/Run2010A-Apr21ReReco-v1/RECO • /Jet/Run2010B-Apr21ReReco-v1/RECO • JSON: Cert_136033-149442_7TeV_Apr21ReReco_Collisions10_JSON.txt • Runs: {141956-148859, 148952-150431}, where the CASTOR HV was unchanged. • With condition: every event is taken from one dataset only (no duplication). • RecHitcorrector is applied, • LeV Scale is applied (0.015 for EM modules). CASTOR meeting, 16 Nov 2011

  14. 2010 data analysis Background estimation: 1. Generate phi, (eta, Energy) for the HF electron using 2010 data distributions 2. Generate phi and energy for the CASTOR electron using 2010 data distributions 3. Invariant mass of these 2 uncorrelated particles will show the background shape. 4. Normalize the results to the number of selected events. (blue histograms on the next slides) CASTOR meeting, 16 Nov 2011

  15. 2010 data analysis Invariant mass distribution for the cuts: 200<EHF 150<ECASTOR<300 For the Primary vertices n=1 CASTOR meeting, 16 Nov 2011

  16. 2010 data analysis Invariant mass distribution for the cuts: 100<EHF<200 GeV ECASTOR>300 LeV For the Primary vertices n=1 The second peak depends on the applied cuts and comes from 3<|ηHF|< 3.5. CASTOR meeting, 16 Nov 2011

  17. 2010 data analysis Invariant mass distribution for the cuts: |η|>3.5 40<EHF<350 200<ECASTOR<1000 For the Primary vertices n=1 Datasets: 2010B – MinBias + Electron + Mu + Jet CASTOR meeting, 16 Nov 2011

  18. 2010 data analysis Invariant mass distribution for the cuts: |η|>3.5 40<EHF<350 200<ECASTOR<1000 For the Primary vertices n=1 Datasets: 2010B – MinBias + Electron + Mu + Jet CASTOR meeting, 16 Nov 2011

  19. Summary Plans • Minimum Bias Monte-Carlo full chain gen-reco • 2011 data analysis • Switch to standard electron reconstruction in the CASTOR CASTOR meeting, 16 Nov 2011

  20. Back-up CASTOR meeting, 16 Nov 2011

  21. Present Absolute Calibration From HF: 581 GeV / (20960 fC / fcastor) = 0.015 GeV/fC (≈ 30% total uncertainty) Test Beam (2008): 0.016 GeV/fC CASTOR meeting, 16 Nov 2011

  22. 2010 data analysis Invariant mass distribution for the cuts: |η|>3.5 40<EHF<75 100<ECASTOR<500 For the Primary vertices n=1 Datasets: 2010B – MinBias + Electron + Mu + Jet CASTOR meeting, 16 Nov 2011

  23. 2010 data analysis Invariant mass distribution for the cuts: |η|>3.5 40<EHF<75 100<ECASTOR<500 For the Primary vertices n=1 Datasets: 2010A – MinBias + EG + Mu CASTOR meeting, 16 Nov 2011

  24. 2010 data analysis Invariant mass distribution for the cuts: |η|>3.5 40<EHF<350 200<ECASTOR<1000 For the Primary vertices n>1 Datasets: 2010B – MinBias + Electron + Mu + Jet CASTOR meeting, 16 Nov 2011

  25. 2010 data analysis Invariant mass distribution for the cuts: |η|>3.5 40<EHF<350 200<ECASTOR<1000 For the Primary vertices n>1 Datasets: 2010B – MinBias + Electron + Mu + Jet CASTOR meeting, 16 Nov 2011

  26. 2010 data analysis Invariant mass distribution for the cuts: |η|>3.5 40<EHF<350 200<ECASTOR<1000 For the Primary vertices n>1 Datasets: MinBias - 2010A+2010B CASTOR meeting, 16 Nov 2011

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