M. Ellis - 11th February 2004 Sci Fi Cosmic Light Yield 2 views 3 views

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 2 nd week of March.  For the data without timing information, tracking should allow us to reproduce the 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.