04-9-2015
I did some TDC ring tests on Detector 4 by adding a 50 Ohm pass through terminator on the base of the top detector and another pass through terminator at the exit of the patch pannel
I needed to recommission the DAQ TDC logic which seems to have become unplugged.
I added connectors so TDC1190[6] would have two hits separated by 400 ns
replay the data on daq2 with the command
CODA/CODAreader/ROOT_V5.30/R1DC/evio2nt -fr4516.dat > /dev/null
R1DC->Draw("(evt.TDC1190[1][3])");
R1DC->Draw("(evt.TDC1190[1][6]-evt.TDC1190[2][6])/10>>(4096,-4096,4096));
Cosmic tests
Detector 4's bottom PMT was used at the trigger (and TDC start) for the DAQ. Cosmic rays were the source of the hits.
Below is the difference in time between the first and second TDC hit from Detector 4's top PMT output.
A second hit is not expected when using cosmic rays as the source. The argument is that any second hit would be due to a reflection (or ring) of the signal.
Both PMT HV were set to 1100 volts and the LED threshold was at 20 mV
run 4518 terminators in
Run 4518 had the bottom PMT of Detector 4 as the trigger and the terminators in.
R1DC->Draw("(evt.TDC1190[1][3]-evt.TDC1190[2][3])/10>>(4096,-4096,4096)");
R1DC->Draw("(evt.TDC1190[1][2]-evt.TDC1190[2][2])/10>>(4096,-4096,4096)"
Difference in time between to first and second hit in Detector 4's top PMT
The TOP PMT did not have many multiple hits when the terminators are attached.
run 4519 terminators out
Run 4519 had the bottom PMT of Detector 4 as the trigger and the terminators out.
Difference in time between to first and second hit in Detector 4's top PMT
The TOP PMT DID have many multiple hits when the terminators are NOT attached.
- I the above a result of attenuating the signal with the terminators or decreasing the reflections.