m. ellis - 11th february 2004 sci fi cosmic light yield 2 views 3 views
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M. Ellis - 11th February 2004
Sci Fi Cosmic Light Yield
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M. Ellis - 11th February 2004
Sci Fi Cosmic Light Yield At Abingdon, reported a light yield of
approximately 4-5 PE. Since then, investigations of more recent data
taken with trigger timing information indicate that this was an underestimate.
VLPC readout is sensitive to the timing of the trigger with respect to the DAQ. Cutting on this time shows a strong effect on the amount of light recorded.
M. Ellis - 11th February 2004
Pedestal Run – All ADCs
Data taken without tracker.
Same code used to subtract pedestals and common mode noise as for all other plots in this talk
M. Ellis - 11th February 2004
ADC for all events – cosmics 5 above pedestal =
16 ADC Trigger wrt DAQ times
range between 170 and 210 ns
Times divided into 10 bins and the mean of all ADCs above 16 determined for each bin in time
Plots on next pages show ADC distribution in bins of time…
M. Ellis - 11th February 2004
Bin 1: 170 –174 ns
Overflow Bin
M. Ellis - 11th February 2004
Bin 5: 186 – 190 ns
Overflow Bin
M. Ellis - 11th February 2004
Bin 9: 202 – 206 ns
Overflow Bin
M. Ellis - 11th February 2004
Mean Light Yield vs Timing For 170 – 190 ns, mean light yield is as reported at Abingdon: 4 – 5 PE.For 200 – 210 ns, light yield is 10 – 11 PE, as expected from the extrapolation from D0.Once tracking is ready, light yield can be confirmed by looking at hits in tracks.
M. Ellis - 11th February 2004
Summary Initial estimate of low light yield was probably
due to a timing problem in the DAQ setup – this will be investigated when the Sci Fi group meets at Fermilab in 2nd week of March.
For the data without timing information, tracking should allow us to reproduce the 10-11 PE determination. Progress has been made on the understanding of the decoding of the cosmic setup and Makoto and I will be working intensively on the analysis in Japan during the last two weeks of February.