Calorimeter tower calibration history

 In preparation for the upcoming calorimeter calibration workshop, I wanted to organize a bit the history of past calorimeter calibration work. Here I summarize what I have found for the calorimeter tower gains calibrations starting a few years back (perhaps not back to the dawn of the efforts, but at least inclusive of the relevant years, I hope).

___________

Methods:

  1. LEDs
    • Only in the barrel
  2. Inverse slopes from ADC spectra
    • Plentiful statistics
    • Only relative gains within eta rings because spectra change with eta
    • Must use lowest portion of ADC spectrum because high end is dominated by showers from inactive material?

  3. MIP peaks
    • Short lever arm
    • Reasonable statistics
    • Can provide absolute gains based on simulations / test beam data (SN 0433)
  4. Electron E/p
    • Needs TPC; doesn't work at large eta
    • Reduced statistics (needs at least 1M tower-triggered pp events)
  5. pi0 invariant mass
    • Complicated by dependencies of invariant mass (pt, eta?)
    • Reduced statistics
  6. Isolated gammas (Tower vs. SMD energy)
    • Gammas identified by SMD

General notes:

  • Barrel gain in the database has been defined in the calibrations to represent the coefficient to convert ADC counts into GeV. So the units are [GeV/ADC]
  • Endcap gain in the database has been defined in the calibrations to represent the coefficient to convert GeV into ADC counts. So the units are [ADC/GeV]
  • pp data provides the cleanest showers, so calibs are generally done in pp years

___________

 

Barrel tower history:

(much of it has been Calibrations)

Online calibs (changed to the HVs) have been documented by Stephen

 

_________

 

Endcap tower history