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Pedestal shift

Pedestal shift. Try to understand the jerks in MET/ crate energy Study using zero bias root-tuple data p11.13.00 SET = S E T positive and negative. Robert Zitoun Stony Brook University Calo meeting December 3, 2002. Crate scalar E T (“raw” SET). y-axis = GeV x-axis = time

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Pedestal shift

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  1. Pedestal shift • Try to understand the jerks in MET/ crate energy • Study using zero bias root-tuple data p11.13.00 • SET = S ET positive and negative Robert Zitoun Stony Brook University Calo meetingDecember 3, 2002 R. Zitoun, Stony Brook and LAPP Calo Meeting

  2. Crate scalar ET (“raw” SET) • y-axis = GeV x-axis = time (run index number 0 to 58) occupancy R. Zitoun, Stony Brook and LAPP Calo Meeting

  3. More detailed SET • 1 plot per card (in crate 2)  1 plot per channel R. Zitoun, Stony Brook and LAPP Calo Meeting

  4. Calibration in the game • Grab from electronic logbook when pedestals were downloaded (not taken!) • Vertical lines R. Zitoun, Stony Brook and LAPP Calo Meeting

  5. Zoom on one channel • Info from online pedestal files meas ped s 0 supp 580.63 2.20 581 580.45 2.11 580 580.80 2.11 581 580.50 2.07 580 580.72 2.12 581 580.88 2.02 581 • Pedestal stable!!!! • How can that explain the ~5 ADC count jumps? R. Zitoun, Stony Brook and LAPP Calo Meeting

  6. Quick simulation < > = –2.1 < > = 3.1 • Generate gaussian ADC values (< >=0.5 and s = 2) • Apply “2.1” s cut for 2 windows shifted by 1 • Mean value • shift anticorrelated with rounded pedestal value • oversensitive to shift • symmetric with respect to 0.5 • Does this channel (microscopic) effect propagate to card/crate SET (macroscopic)? R. Zitoun, Stony Brook and LAPP Calo Meeting

  7. Macroscopic effect • –sum of rounded pedestals in a card  measured SET in card R. Zitoun, Stony Brook and LAPP Calo Meeting

  8. Why coherent effect? • L1 SCA problem? • In a calibration run, only some L1 SCA cells are hit • Large dispersion of pedestal within L1 SCA • Calibration run to run fluctuation of cell blend • SCA behave roughly in the same way R. Zitoun, Stony Brook and LAPP Calo Meeting

  9. Get rid of the rounded pedestal jumps ADC time • Put all data from 58 runs with only one pedestal per channel • Use a real 2.5 s cut Little data lost (≥±2) • Now much flatter (not for all crates) • 2.5 s cut alone improves but jumpsstill present R. Zitoun, Stony Brook and LAPP Calo Meeting

  10. Back to SET per crate • true 2.5 s cut  pedestal jump corrected R. Zitoun, Stony Brook and LAPP Calo Meeting

  11. Summary • Most features of SET in crates dominated by jumps in rounded pedestal • Proposal Do not change the rounded pedestal (and the 1.5s cut) if its value moves by ±1 (or ± a certain fraction of s) R. Zitoun, Stony Brook and LAPP Calo Meeting

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