1. Equipment Tests for DHC Tower
Kurt Francis - Northern Illinois University
Update - 08/27/2003

2. Introduction
Received loaner QDC (similar to original but 16 vs 32 channels)
Did data runs with two of six new PMTs
First assesment showed that light yield was ~1/2 what we had before
Then we received repaired QDC and had similar results
We were worried that the 2 times difference in light yield was too much

3. Current Status
Collected data with one new PMT with both upper and lower sets of repaired QDC channels
Used ROOT command line programming to:
remove pedestal
find cutoff between crosstalk curve and MIP curve
use root functions to find mean of crosstalk peak and MIP peak
use this data to calculate Light Yield
Used the same ROOT processing on both and old data set and the data collected with the repaired board...

5. Conclusions about PMT L.Y.
Definitely a difference between the before and after light yield plots but not as bad as 2 times
The difference in average light yield (11.0 compared to 7.9) is within a reasonable range for two different PMT

6. Tower Data
First test of tower used 4 layers of cells connected to 2 PMTs.
PMT HV set at 900V
Triggering was 2 way coincidence using two Thorn-EMI PMTs connected to paddle scintillators
--> High rate of events but most events 99% were pedestal
Need to switch to 3 way coincidence using dynode 12 from PMT

7. Next Steps Keep improving ROOT based analysis software
Clean up triggering and switch to 3 way trigger using 2 external PMTs and dynode 12 from one of the multichannel PMTs