Calibration
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Calibration. Munich group version Checks. Idea. Calibration runs : same number of photons in all PMs Flat fielding: same pixels output from calibration runs Calibration methods: Ffactor method (relative calibration) Blind-pixel method (absolute calibration)

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Calibration

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Calibration

Calibration

Munich group version

Checks


Calibration

Idea

Calibration runs:

same number of photons in all PMs

Flat fielding:

same pixels output from calibration runs

Calibration methods:

Ffactor method (relative calibration)

Blind-pixel method (absolute calibration)

We did consistency checks

Nadia Tonello, MPI


Jan feb 2004 which method for calibration

Jan –Feb 2004Which method for calibration?

1. Blind pixel had (hardware?) problems:

-many bad runs

no calibration constants

2. Ffactor method:

- reasonable results

pedphotcalc.C

- simple to check

new independent class to compare the resulting conversion factors

Nadia Tonello, MPI


How we calibrate same scheme as calibcalcphotons c

How we calibrate...Same scheme as calibcalcphotons.C

1. Extraction of Pedestalsfrom pedestal runs in FADCcounts using MPedCalcPedRun

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How we calibrate

How we calibrate...

2. Calculation of calibration factorsusing signal estracted from calibration runs by MCalibrationChargeCalc etc.

~23 photoelectrons for inner pixel area

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How we calibrate1

How we calibrate...

3. NEW: Flat fieldingof the number of photons in the calibration-run.

~135 photons for inner pixel area

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How we calibrate2

How we calibrate...

NEW calibration factors: multiply the previously calculated with the correction factor for flat fielding.

~ 3.5 photons/ FADC count

~ 0.8 photons/ FADC count

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How we calibrate3

How we calibrate...

4.Calibration of data and pedestalsusing MCalibrate Data

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Calibration

How we checked it:New Class to calculate the conversion factors with the Ffactor method(used instead of MCalibrationChargeCalc etc.)

QinMean charge for the inner pixels excluding cosmics and bad pixels

ciCorrection factor to flat field the charges

sQmdistribution obtained summing all the charge distributions of the pixels after flat fielding

sredfrom the mean corrected pedestal RMS

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How we checked it

How we checked it:

QinMean charge for the inner pixels excluding cosmics and bad pixels

~160 FADC counts

channel

channel

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How we checked it1

How we checked it:

ciCorrection factor to flat field the charges

~160 FADC counts

channel

channel

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How we checked it2

How we checked it:

sQmdistribution obtained summing all the charge distributions of the pixels after flat fielding

sQm~43 counts

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Calibration

Mean number of photoelectrons

Nphel = (Qin2/ s2red)F2

where F2= 1.335 (as in MCalibrationChargeCalc)

Conversion factors:

(Ph/FADCcount)i = Nphel ci / Qin /phxpe

where phxpe= 0.18 (as in MCalibrationChargeCalc)

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Result

Result:

Calibration factors in agreement

~ 3.5 photons/ FADC count

~ 0.8 photons/ FADC count

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Check inner outer pixels pe

Check inner-outer pixels: pe

Inner pixels: 23 pe/area

Outer pixels: 13 pe/area

npeI= 1.8 npeO

npe= 0.18 ng

ngI

npeI

1

0.18

=

= 5.6

ngO

npeO

1.8

0.18

= 10

=

ngI = 0.25 ngO

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Check inner outer pixels f 2 qe

Check inner-outer pixels: F2/QE

npeO

npeI

Calculated

Considering the

same Ffactor I,O

= 2.22

npeI =23

npeO =13 · 4 = 52

npeO

npeI

npeO

npeI

FI2

FO2

real

=

ngO

ngI

npeO

QEO

QEI

npeI

QEI

QEO

npeO

npeI

FO2

FI2

=

=

= 4

F2O

QEO

F2I

QEI

= 1.8

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Check inner outer pixels conversion factors

Check inner-outer pixels: conversion factors

Inner pixels: 165 FADCcounts

Outer pixels: 150 FADCcounts

ngI

nADCI

ngI

npeI

npeI

nADCI

=

= 0.78

~ 3.5 photons/ FADC count

~ 0.8 photons/ FADC count

ngO

nADCO

ngO

npeO

npeO

nADCO

=

= 3.46

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Check inner outer pixels pedestal rms

Check inner-outer pixels: pedestal RMS

Inner pixels: 7 FADCcounts per slice

Outer pixels: 5 FADCcounts per slice

ngI

nADCI

ngI = 7

= 5.5

ngO

nADCO

ngO = 5

= 17.3

~ 17 photons/ FADC slice

~ 6 photons/ FADC slice

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Conclusions

Conclusions

  • In Munich we calibrate using the Ffactor method and flat fielding

  • Our checks pointed out that the results are consistent

Nadia Tonello, MPI


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