SLAC fDIRC data processing for Hawai’i electronics

(SLAC experiment T-492 )Larry Ruckman & Gary Varner

Instrumentation Development Laboratory (ID-Lab) University of Hawaii at Manoa

October 4, 2007

First data skimming

• Converts from raw ADC counts to voltage• Keep any event with 1 or more of the 12

waveforms with hits below -40 mV• Perform a FFT filter to the same response as

front end electronics low-pass filtering• Maintain the event number with the

corresponding skimmed data event• Skip over and does not write to file the events

with no photodetector signals• After processing, raw data files get tar.gz and

stored onto DVDs

Before FFT filtering

-350

-300

-250

-200

-150

-100

-50

0

50

100

0 10 20 30 40 50 60 70 80 90

time (ns)

volta

ge (m

V)

After FFT filtering

-350

-300

-250

-200

-150

-100

-50

0

50

100

0 10 20 30 40 50 60 70 80 90

time (ns)

volta

ge (m

V)

-40 mV Cutoff

Skimmed EventsDiscarded events

Summary

• Done transferring all raw data from SLAC to UHM• Processed 1219 of 1619 1/2 GB raw data files• 69 raw data storage DVDs have been made (150k raw

events per DVD)• Over 1.4 million skimmed events obtain from 12.2 million

processed raw data events • Need to organize files with respect to beam position• Next, apply pulse fitting algorithm and charge algorithm

to obtain a time and charge for each skimmed event