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ICD Energy Calibration Andy White January 16, 2002

ICD Energy Calibration Andy White January 16, 2002.  ICD in Run I -> Expectations for Run II  ICD coverage in Run II 1.1 <  < 1.4 ieta  = 12, 13, 14  Ingredients of the ICD energy calibration. ICD Status.

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ICD Energy Calibration Andy White January 16, 2002

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  1. ICD Energy Calibration Andy White January 16, 2002

  2.  ICD in Run I -> Expectations for Run II  ICD coverage in Run II 1.1 <  < 1.4 ieta  = 12, 13, 14  Ingredients of the ICD energy calibration

  3. ICD Status  All ICD components are fully installed and ICD is being read out Timing of ICD relative to Calorimeter understood  5/378 channels give low/dead response - will need access to fix  Learning to use LED Pulser as monitor

  4. South ICD - before fiber cables installed

  5. INGREDIENTS • ADC to GeV Conversion factor • Sampling fractions • Tile to tile variation

  6. The ADC to GeV conversion depends on the following factors: • 1) The specific energy loss (dE/dx) in the Bicron BC-400 scintillator. • This is a PVT scintillator so • dE/dx (min) = 1.956 MeV/(g/cm**2) x 1.032 g/cm**3 = 2.02 MeV/cm • 2) Mean MIP peak in teststand ADC counts. From Mark’s distribution of June 2001 the mean for 368 channels was 135.7. (We were aiming for 140).

  7. 3) The relative gain factor between calorimeter preamps (used on the teststand) and the ICD preamps. This factor was measured at the teststand to be 3.8. • 4) The extra amplification of x8.7 that we used to boost the signal on the teststand. • 5) The factor of 10 between the least count of the teststand ADC’s and the calorimeter ADC’s. The least count for the teststand ADC is 1 mV and for the calorimeter is 0.1 mV.

  8. 6) The “cosine factor” that accounts for the angle of a normal to an ICD tile relative to a straight line drawn from the IP through the center of a subtile. There are three numbers, one for each eta bin covered by the ICD: • Eta cosine factor • 12 0.592 • 13 0.633 • 14 0.671 • However, NOTE that the sampling fractions ALSO include this angular factor – so we must be careful not to use it TWICE! • 7) The thickness of an ICD tile. All tiles are 0.5 inch thick = 1.27 cm.

  9. Therefore the average MIP peak position in calorimeter ADC counts is given by • (135.7 x 10) / (3.8 x 8.7) = 41.0 counts • Using this with the other factors give the energy deposition in an ICD tile as: • ( Cal. ADC count / 41.0) x ( 2.02 MeV/cm x 1.27 cm) • Finally this gives the energy deposition as: • Cal. ADC count x 0.06257 (MeV) • = Cal. ADC count/15982 (GeV)

  10. Sampling fractions  Present values are from a Monte Carlo simulation by Vishnu using 20 GeV/c single pions  From caltables: float Weight_icd1 = 72.6591 //ilayer = 9, |ieta|==12 float Weight_icd2 = 69.5046 //ilayer = 9, |ieta|==13 float Weight_icd3 = 63.4282 //ilayer = 9, |ieta|==14

  11. Tile to tile variations  Each tile + fiber cable + PMT combination was calibrated using cosmics on the ICD teststand  These combinations stayed together on the detector (apart from changes due to failures)  The variation from the mean response is available and will be used as an additional correction factor (see talk by Andre…)  These data should be in DB as some run dependence is expected

  12. ICD tiles - teststand results

  13. CONCLUSIONS  All factors are in hand to achieve initial ICD calibration  Need to study effects of ICD contributions on response across ICR  Need high statistics di-jet and jet- samples -> float sampling fractions to optimize correction -> do we need phi dependent fractions?

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