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Azimuthal symmetry of HCAL readouts

Azimuthal symmetry of HCAL readouts. O. Kodolova (SINP MSU). f symmetry: goal and data stream choice. Goal is to install the relative scale within each eta-ring. - using the phi-symmetric events equalize the response of HCAL readouts

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Azimuthal symmetry of HCAL readouts

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  1. Azimuthal symmetry of HCAL readouts O. Kodolova (SINP MSU)

  2. f symmetry: goal and data stream choice Goal is to install the relative scale within each eta-ring. - using the phi-symmetric events equalize the response of HCAL readouts - choice of data stream may be different for the different eta regions: HB/HE/HF Current data stream choices: - minbias events - low momentum isolated tracks (10-15-25 GeV) Both choices have + and - features

  3.  symmetry with minbias events The estimation of mean energy per readout: <Ereadout> = <Esignal>+<Enoise> The variance estimation: <Vreadout> = <Vsignal>+<Vnoise> The mean energy and variance in the ring: <Ering> = <Esignal>+<Enoise> <Vring>=<Vsignal>+<Vnoise> Noise mean values and variances have to be estimated either from the same event using first time slices (startup scenario) or from pedestal runs (when pileup starts).

  4.  symmetry with minbias events: calibration procedure Coefficients are derived from non-calibrated sample for each readout i in each -ring j after Noise subtraction Mean values: Cij = <Eij>/<Ej> or variances: Cij = sqrt(<Vij>/<Vj>) Coefficients are applied and the new readout response is: Note: to avoid noise/signal correlations special runs without zero-suppression in HCAL Eij corrected = Eij/Cij Project was started in 2006 and was tested with CSA06/CSA07/CSA08/CRAFT

  5.  symmetry with minbias events: noise contribution Ring: Eta=1 depth=1 10 mln (noise+signal) Vreadout, GeV2 Signal is much less then noise in barrel -index 2 mln (noise) CSA07 data Vreadout, GeV2 -index

  6.  symmetry with minbias events: needed statistics estimation Depends on the noise value, i.e. Most critical for the central barrel ieta-ring<5. 1. Calibration with mean value: Mean noise = 10-5 with RMS=0.2-0.3 GeV Mean signal HB: 0.002 GeV (ieta=1) HB: 0.008 GeV (ieta=14) HE: 0.03 GeV (ieta=21) HF: 0.5 GeV (ieta=35) 2. Calibration with variance: Mean Noise variance =0.084, RMS=0.24 GeV2 fluctuates channel-to-channel Mean variance HB: 0.005 GeV2 (ieta=1) HB: 0.008 GeV2 (ieta=14) HE: 0.059 GeV2 (ieta=21) Error of noise RMS/sqrt(N) < 0.02 * Esignal N=25 mlns events for HB, ieta=1 Error of noise RMS/sqrt(N) < 0.02 * Vsignal N=6 mlns events for HB, ieta=1

  7. Coefficients vs number of events in HF, ieta=32 (2-dim vs if) 900k 90k 8.9 mlns 1.8mlns

  8. Coefficients (ideal calibration) with variances for 9 mlns events HB, ieta=1 HE, ieta=23 Material effects Channels with large noise RMS require higher statistics (optimistic) or can not be included in f-symmetry if noise distribution is essentially non-gausian HF, ieta=32

  9. Accuracy vs number of events (IDEAL calibration) h<0 Black: 90K Red: 900K Green: 1.8mln Pink: 8.9mlns Large noise channels were extracted from the calculations. HE HF HB The best accuracy that can be achieved with 9 mlns of events and current noise map

  10. Azimuthal symmetry jobs with CRAFT L1 trigger : EG and Muon AlCaRAW is created at HLT step to be sent to Tier0 only HCAL RAW data (without zero-suppression) Special reconstruction at Tier0 followed by AlCARECO production Time slices 1-4 for noise reconstruction Time slices 5-8 for signal reconstruction 160 mlns events are at CAF: same amount for noise and signal events. 50 mlns were analyzed: 4 days of data collected from 29st of Oct to 1st of Nov. ~2 days with HF on. It can be used to study the level of noise and noise stability

  11. Variance distributions in HB (50 mlns NZSP events) Ieta=-1 iphi=70 HB iphi 2 3 4 ieta Var(ieta,iphi) with selection: Var=[0.22-0.26] Same noise map/gains were in CMSSW: Slides 1-8 Iphi=70 ieta=-1 Energy distribution in the readout iphi=70, ieta=-1 twice wider then “normal” readouts due to small conversion factor. Peak 4 E, GeV

  12. Peaks origin (example with HB) Peak 1 Peak 2 Peak 3 Peak 4 Problematic HPD, iphi=70 Var>0.1

  13. Variance stability From 29th Oct to 1st of Nov HF was on later (on 30th Oct?) HB, iph=70. ieta=-1 HF, ieta=36, iphi=3 Something happened HF, ieta=36 Variances are stable, but sometimes we observe fluctuations that required the additional study.

  14. Phi symmetry with Isotracks Method: cell-by-cell calibration with isotracks Problems: - statistics for tracks with P>15 GeV/c we need a few hundreds MIP tracks per cell - material effects which depend on track energy - shower profile vs energy ? We will use the interval from 15 to 25 GeV or from 10 to 25 GeV - Zero suppression affects low momentum tracks ?

  15. Cell by cell calibration with 50 GeV ~45 tracks/cell ~22 tracks/cell Material effects ~100 tracks/cell From G.Safronov, A.Anastassov ~900 tr/cell

  16. Summary Phi symmetry in high -h region (outside tracker) can be done with minbias events with accuracy less than 1 %. For HB we can reach 3-3.5% in rings ieta<5 and 2% in ieta=5-14 and in HE. ~10 mlns events have to be collected in special NZSP run. The possibility was checked with CSA07/CSA08/Latest generation with CMSSW219(IDEAL calibration)/CRAFT. Phi symmetry in HB/HE can be done/cross-checked with isolated tracks sample. However this possibility needs some additional study. More study need to be done with Cosmic (noise stability) and with new simulation with the latest noise/gains. Latest presentations: http://indico.cern.ch/materialDisplay.py?contribId=2&materialId=slides&confId=51006 http://indico.cern.ch/getFile.py/access?contribId=68&sessionId=2&resId=0&materialId=slides&confId=46352

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