Transcript ppt

ACD calibrations
Pedestals
Measured from online script
Measure PHA w/ HV off, no charge injection
Use cyclic triggers
~100-300 ADC counts, very narrow (rms 2-3 counts)
Gains
Measured from self-triggered data
Look for MIP peak w/ HV on
W/ full LAT use TKR extrapolation
W/ ACD only use coincidence to reduce angular distribution
PHA distribution in a single channel
Zero suppression is on for these data (15 cts above pedestal)
Low energy noise
Seen in both PMT
(probably x-rays in
same shower as muon)
MIP peak
Veto threshold (0.3 MIP)
Fitting the MIP peak
Following procedure from
ACD group, fit to polynomial
Around MIP peak and
Extract peak value
To determine fit range
1) Find local min between
low energy noise & MIP
2) Find MIP peak
3) Find ½ max value after
MIP peak
Fit between 1) and 3)
Robustness of fitting procedure
Procedure is pretty robust for tiles.
On first calibration run tried it only
failed in 1 out of 178 PMTs.
Need to pick a fallback option anyway.
Ribbons don’t have a clear MIP peak
Need more work on these
Scatter in MIP peak values