CURRENT VALUES
ideal mode calibrations are based on measured means of Cal Flight Models.
They are not well suited to real data as they treat all crystals as equal, while the varying pedestals in real
data could cause some ideal calibrations to be out of range.
'flight' mode calibrations are intended for simulating flight energy levels.
The effective reponse of the current configuration is as follows
NEWIDEAL_FLIGHT2
RANGE MeV/ADC MAX_ADC SATURATION(MEV) PED(ADC) NOISE(ADC,MeV) LAC(ADC,MeV)
LEX8 0.03 3550 109 510 6.0, 0.18 43, 1.29
LEX1 0.27 3850 941 210 0.6, 0.162
HEX8 2.16 3550 7676 510 6.0, 8.823
HEX1 19.23 3850 74,016 210 2.1, 32.30
it incoperates the following improvements over the prievous version.
- HE gain setting is set to maximum energy range, raising single xtal saturation level.
- ULD values for all ranges and HEX1 saturation level are set to very close to 4095. The previous values were lower in an effort to avoid problems caused by channels w/ higher pedestals which is not an issue in ideal mode
- LAC threshold was raised to 1.3 MeV which is closer to the mean LAC threshold used for flight crystals
- pedestal noise levels are lower to better reflect the true behavior of the flight front-ends
- some values were rounded a bit just to make things simpler.
HISTORY OF VALUES
This documents the history of CalXtalReponse ideal calibration effective gain & noise for versions <= v0r3 at which point documentation will be included in the header of each xml file.
NEWIDEAL_FLIGHT (CalXtalReponse v0r2p8 -> v0r2p7, GlastRelease v6r6 -> v6r6p1) RANGE MeV/ADC MAX_ADC SATURATION(MEV) PED(ADC) NOISE(ADC,MeV) LAC(ADC,MeV) LEX8 0.03 3400 109 510 5.1, 0.153 30, 0.9 LEX1 0.27 3400 941 210 2.1, 0.567 HEX8 1.73 3400 5913 510 5.1, 8.823 HEX1 15.38 3400 52,000 210 2.1, 32.30 NEWIDEAL_MUON2 ( CalXtalReponse v0r2p6, GlastRelease v6r4 -> v6r5) RANGE MeV/ADC MAX_ADC SATURATION(MEV) PED(ADC) NOISE(ADC,MeV) LAC(ADC,MeV) LEX8 0.03 3400 109 510 5.1, 0.153 30, 0.9 LEX1 0.27 3400 941 210 2.1, 0.567 HEX8 0.17 3400 591 510 5.1, 0.867 HEX1 1.53 3400 5,200 210 2.1, 3.213 NEWIDEAL_MUON1 ( CalXtalReponse v0r2 -> v0r2p5, GlastRelease <= v6r3p2 ) RANGE MeV/ADC MAX_ADC SATURATION(MEV) PED(ADC) NOISE(ADC,MeV) LAC(ADC,MeV) LEX8 0.03 3500 112 510 5.1, 0.153 30, 0.9 LEX1 0.27 3500 968 210 2.1, 0.567 HEX8 0.17 3500 608 510 5.1, 0.867 HEX1 1.53 3500 5,352 210 2.1, 3.213
HOW IT WORKS
basically, there are two stages.
Recon
1) ADC->DAC
2) DAC->MEV
digi is the opposite of course, but it is done in pieces. first the dac 'scale' values for the individual McIntegratingHit energies are summed together, once they're all summed, then we convert dac->adc.
here are the constants from CalXtalResponse/xml/idealCalib.xml file.
<item name = "LARGE" value = "0.36"> Large diode MevPerDac </item> <item name = "SMALL" value = "2.0"> Small diode MevPerDac </item> <item name = "ADC_PER_DAC" value = "11.2, 1.3, 11.5, 1.3"> ADC/DAC
for each ADC range </item>
so for LEX8 recon would go something like this:
dac = adc/11.2 // 11.2 is the LEX8 val for adc_per_dac mev = dac*0.36 // using large diode MevPerDac.
so final ratios are:
LEX8 ADC/Mev = 0.0321 LEX1 = 0.27 HEX8 = 0.17 HEX1 = 1.5
all ranges are currently maxing out at 3500 ADC (including pedestals) pedestals are about 500 in X8 and 200 in X1 this makes the max measurable energy in HEX1 (3500-200)/1.5=2.2gev per xtal. i don't know if that's a problem or not, like i said before these numbers are averages from muonCalib which uses different gain settings from flight.
incidentally, all these values can be changed instantly by editing the idealCalib.xml file (so you can see the effect of changing gains, peds, etc...).