# Presentation: 715967

## 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

-   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

## South ICD - before fiber cables installed

## Slide 5

## Slide 6

## INGREDIENTS

-  ADC to GeV Conversion factor
-  Sampling fractions
- Tile to tile variation

## 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).

## 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.

## 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.

##               =  Cal. ADC count/15982  (GeV)

-                  (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)

## 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

## 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

## ICD tiles - teststand results

## 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?