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ECAL status & studies

Irina Machikhiliyan , 10.10.2012. ECAL status & studies. Tech. stop activities (Sept 2012). Irina Machikhiliyan , 10.10.2012. Latest Monitoring system repair (tech stop Sept 2012): One noisy LED group C107 ( 2 LEDs, 32 detector cells).

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ECAL status & studies

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  1. Irina Machikhiliyan, 10.10.2012 ECAL status & studies

  2. Tech. stop activities (Sept 2012) Irina Machikhiliyan, 10.10.2012 • Latest Monitoring system repair (tech stop Sept 2012): • One noisy LED group C107 ( 2 LEDs, 32 detector cells) Also: LED intensity tuning for two LEDs (two cells were in saturation) CELL O 16/46 (LED C107.1) CELL O 23/49 (LED C107.2) Peak R.M.S. Peak R.M.S. Run 129805 (4 Oct) Run 127001 (2 Sept) Run Number Tech. Stop 17-21 Sep, cabling repair LED Spectrum

  3. Irina Machikhiliyan, 10.10.2012 Relative ECAL adjustment on the basis of raw occupancies

  4. ECAL occupancies: definition Irina Machikhiliyan, 10.10.2012 Typical ADC spectrum (~300K of noBias events, one hour of data taking). Typical occupancy map for ECAL (~300K of noBias events, μ = 1.592) OCC = Nentries(adc_reading > threshold) / Nentries Threshold is set to 18 ADC counts (for ECAL it is equivalent to ≈ 0.05 GeV of transverse energy) Nentries(full) is the same as the number of events Cell O 04/08 (one of Outer most peripheral, i. e. worst statistical case) ADC counts threshold

  5. ECAL occupancies: method Irina Machikhiliyan, 10.10.2012 • Idea: • Fix occupancy map for certain run as the reference (e.g. the run where the fine calibration is available) and then correct detector response drift due to rad. damage, PMT, etc. on the level of individual cells, using ratio of occupancies • Benefits: • raw ADC readings, which means that no reconstruction, no information from other sub-detectors, no alignment, etc is required • noBias data: at fixed beam energies the only normalization required is the one on μ (see below). The following slides: occupancies are always normalized on μ. • processing is very fast • statistics collected during one [typical] fill will be enough (see below) • correction is possible for each individual cell • Limitations: • will not provide or improve absolute calibration, only allowing relative adjustment to keep trigger rates and detector response more or less stable • precision: particle flux stability; ECAL resolution; • does not take into account changes in PRS/SPD response (though as concerns rad. damage, it should be correlated with the ECAL damage) Theoretically, absolute calibration is possible if one takes MC occupancy map as the reference, but it requires very good MC description…

  6. ECAL occupancies: check #1 (1) Irina Machikhiliyan, 10.10.2012 • Data Samples: • 28 Aug: run 126660, Fill 3011, μ = 1.724 • 29 Aug: ECAL HV change • 31 Aug: run 126831, Fill 3016, μ = 1.592 • Conditions: • Raw Data files • NoBias stream • Parameters: • Parameter #1 (P1) – normalized occupancy ratio [OCC(126831) / μ(126831)] / [OCC(126660) / μ(126660)] • Parameter #2 (P2) – required gain change (input parameter for HV adjustment)

  7. ECAL occupancies: check #1 (2) Irina Machikhiliyan, 10.10.2012 Occ Change Vs Gain Change P2(req. gain change) P1 (normalized OCC ratio)

  8. ECAL occupancies: check #1 (3) Irina Machikhiliyan, 10.10.2012 All Cells Inner P1 /P2 P1 /P2 Middle Outer P1 /P2 P1 /P2

  9. ECAL occupancies: check #2 dependence on μ (1) Irina Machikhiliyan, 10.10.2012 • Data Samples: • 31 Aug: run 126831, Fill 3016, μ = 1.592 • 02 Sep: run 126972, Fill 3020, μ = 1.700 ratio: μ(126972)/μ(126831) = 1.0678 • Good agreement taking into account 2days of data taking in between + couple of days without beam before fill 3016

  10. ECAL occupancies: dependence on μ (2) Irina Machikhiliyan, 10.10.2012 All Cells Inner Occ(126972) / Occ(126831 Occ(126972) / Occ(126831 Middle Outer Occ(126972) / Occ(126831 Occ(126972) / Occ(126831

  11. ECAL occupancies: dependence on μ (3) Irina Machikhiliyan, 10.10.2012 P1 (normalized OCC ratio)

  12. ECAL occupancies: check #3 Verification with π⁰’s (2) Irina Machikhiliyan, 10.10.2012 • Data Samples (1 hour of data taking each): • 15 May: run 115556 – taken as the reference • 17 Jun: run 118828 Both runs: reco 13a (all CaloCalib coefficients were set to 1) P1 (normalized OCC ratio)

  13. ECAL occupancies: check #3 Verification with π⁰’s (2) Irina Machikhiliyan, 10.10.2012 Calo data for run 118828 (bhadron stream) were re-reconstructed using coefficients obtained from normalized occupancy ratios Input: photons from Phys/StdLoosePhotons/Particles Selection cuts: Et(γ) > 200 MeV, Et(γγ) > 1 GeV; NoSpd3x3

  14. ECAL occupancies: statistical error Irina Machikhiliyan, 10.10.2012 Relative Error for normalized occupancies ratio Run #1: 126660, 1 hour of data taking, μ = 1.724 Run #2: 126661, 1 hour of data taking, μ = 1.736

  15. ECAL occupancies: check #4 stability during the fill Irina Machikhiliyan, 10.10.2012 Fill 3011 (28 Aug): • Runs 126660 … 126673 (~9 hours), μ ≈ 1.7 Parameter: R(run) = <OCC(run)/OCC(126660)>, OCC – occupancy, normalized on average μ for current run

  16. Irina Machikhiliyan, 10.10.2012 UNEXPECTED (for me, at least)

  17. Irina Machikhiliyan, 10.10.2012 There were two periods when data were taken / initially reconstructed with calibration constants 1. (after HV tuning): • Fill 2596 (7 May, run 114752) – Fill 2737 (17Jun, run 118828), CONDDB 20120420 • Fill 3016 (31 Aug, run 126831) – Fill 3071(16 Sep, run 128480), CONDDB 20120829 OCC(118828) / OCC(114752) OCC(128480) / OCC(126831)

  18. Period I Irina Machikhiliyan, 10.10.2012 OCC(115454) / OCC(114752) OCC(115556) / OCC(115454) OCC(118828) / OCC(11556) MAGNET POLARITY CHANGE: DOWN → UP

  19. Period II Irina Machikhiliyan, 10.10.2012 OCC(128100) / OCC(128631) OCC(128418) / OCC(128100) MAGNET POLARITY CHANGE: DOWN → UP

  20. HCAL occupancies Irina Machikhiliyan, 10.10.2012 OCC(128100) / OCC(128631) OCC(128418) / OCC(128100) MAGNET POLARITY CHANGE: DOWN → UP

  21. Attempt to increase the threshold Irina Machikhiliyan, 10.10.2012 OCC(128480) / OCC(126831), threshold 18 OCC(128480) / OCC(126831), threshold 50 Check with LEDs PmPin(115556) / PmPin(115454) PmPin(128418) / PmPin(128100)

  22. Check with π⁰ Irina Machikhiliyan, 10.10.2012 Input: photons from Phys/StdLoosePhotons/Particles Selection cuts: Et(γ) > 200 MeV, Et(γγ) > 1 GeV; NoSpd3x3 No obvious changes in energy scale Number of π⁰ in the Outer: (?) reflects change in charged tracks distribution (?) (prefer to check more data / other streams before making any statements)

  23. Conclusions Irina Machikhiliyan, 10.10.2012 • Fast tuning / monitoring of ECAL response, based on occupancy values ispossibleon the level of individual cells. Let’s try? • Asymmetrical change of occupancy map with magnet polarity change (up to 20% in the Outer) • ECAL energy scale seems to be unaffected • as concerns occupancy tuning / monitoring, the effect can be easily compensated by comparing occupancies for two fills before and after polarity change and then producing the new reference map, but… • the reason? How it affects charge particles’ distribution? Can it be seen in MC?

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