Download - Noisy ad nausea?

R. Zitoun, Stony Brook and LAPP Cal Meeting July 15, 20031

• Yuri very upset with noisy events screwing his analysisProvided tens of event displays with bad features

• Bob sees differences between trigger and precision energies

• Use runs around 174500

Noisy ad nausea?Robert Zitoun

Stony Brook and LAPP Cal MeetingJuly 15, 2003


Noisy ADC cards• ADC cards cover 8 BLS boards/trigger tower

• CC: 0<||<1.2 × 4 lines in (not all)

• EC: 1.2<||<4.5 × 4 lines in (not all)


How to Catch Those?• Assumption

• coherent noise for all 384 channels read by the same ADC card

• same value in ADC counts

• Method: tag cards with

• high occupancy

• low energy per channel

• low rms among channels

• Method

• go back from E to ADC counts

• look only at EM channels (HAD have higher noise, thus zero suppressed)

• don’t consider high cells (>3.3)

• count no of cells with energy per ADC card and compute occupancy (wrt no of EM channels)


ADC Card Occupancy• Find the occupancy for all 144 cards in the event

• Find the highest occupancy

cut at 0.5


Energy in highly occupied Cards• Compute <ADCi> and rms(ADCi) for cells in cards with

(individual) occupancy > 50 %

<ADCi>

rms(

AD

Ci)

all events


Zoo


More Zoo

↓ Negative cells ↓


To be continued...• Localization of bad “cards”

• Same patterns with recent runs

• Same pattern if 0.4<occupancy<0.5 (less pronounced)

even less for 0.35<occupancy<0.4

ECN CC ECS CC ECN