1. 1 Initial Tests of DHC Tower Update - 09/03/2003 Kurt Francis, Donna Kubik - Northern Illinois University

2. 2 Current Status DHC Tower is operating with 4 layers of cells Trigger is based on 3 way coincidence of two external PMT/scintillator paddles and Dynode 12 of one PMT Tower is collecting cosmic rays at low rate

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5. 5 Summary Low rate of about 1.2 events/minute (compared to 2 events/minute with test stand) - due to the paddles having a greater separation then with earlier setup 1.25m compared to.45m Using dynode 12 from one of the multichannel PMTs is a good way to generate additional trigger signal We needed to adjust the delay from the dynode 12 signal because the data pulse was not being integrated inside trigger/gate Three of the cells/ channels do not seem to work - still need to debug MIP peak close to pedestal - low amount of light due to lower HV setting of PMT (900V) and smaller fibers Pedestal is ~86% of events -> data=~14% of events or about 1/7 - which is expected since there are 7 cells -> good efficiency

6. 6 Next Steps Keep improving ROOT based analysis software Debug non-working channels Collect more statistics Find the single photoelectron peak for the 2 PMTs we are currently using so we can determine the Light Yield Do more careful tests to determine efficiency Attempt to track particle through four layers