Tracking Pedestals for FermiLab test beam data taken in May of 2007 , based on run May7_run34

Method B: Assume chip peds are describe by linear relation : A+B*stripID . Allow A,B vary event by event

Example of one event: raw (top) , after ped correction (bottom). Plane U (V) spans X-axis 0-191 (192-383).
Vertical green lines mark chip boundaries. Found pedestal per chip is marked be the ~horizontal green line. (Similar 200 events (PDF) )

  1. Detector layout (zom in)

  2. Example of raw ADC spectra for 3 different strips. Note, signal is below pedestal, overflow is at 0.

  3. The same channels after pedestal correction procedure described below. Now sign of ADC is reversed so the values grow w/ energy.

  4. Details of multiple-pass pedestal correction method B.
    a) accumulate raw spectra for every strip, find largest pedestal peak, fit gaussion, drop broken strips with too narrow or out of range peak. (see previous version of the pedestal algoA )
    b) discard strips at the begin/end of chip - show abnormal pedestal fluctuation.
    c) Paramterize ped(stripID)=ped0+tgPed*stripID for every event and every chip using:
    d) accumulate ADC strip spectra corrected for chip_pedestals and determin stip dependent (constant per run) pedestal correction (stripPed).
    e) final ADC ~ energy= -( rawADC(eve) - chipPed(eve) -stripPed)

  5. List of discarded strips and strip pedestal (after chipPed correction)

  6. Assumed resulution and position of average pedestals for chipPedestal fit.
    chipID pedSig
    0 6.5 550
    1 10 570
    2 12 650
    3 10 640
    4 12 620
    5 dead

  7. QA cuts requirements (actual fit formula f(ch)= ped0 + tgPed*(ch-ch0) decouples slope from the constant )
    * chi2/dof in [0.05,2.0]
    * |ped0-pedMean| <100 ADC counts
    * tgPed in [-0.5,1.5]

  8. distribution of chi2/DOF (before cut) for all 5 disk

  9. distribution of ped0 (before cut) for all 5 disk

  10. distribution of tgPed (before cut) for all 5 disk

  11. Distribution of strip pedestals position (top) & width (bottom) _after_ chipPed subtraction and _before_ stripPed correction. (plots for all strips ) Dead strips are red.

  12. Distribution of strip pedestals after both chipPed & stripPed correction: plots for all strips

  13. Used code is here