1. The procedure for noise rate measurement of BBC’s PMTs
Hiroyuki Harada
Hiroshima University
Mail :
Hiroyuki Harada

2. Purpose of this measurement
The purpose of this measurement is to understand the condition of PMTs, which good or bad, by measuring and checking noise rate of PMTs.
Thus,
For comparing condition of PMTs, we must take a data of noise rate under same assumption.
Hiroyuki Harada

3. Equipment for set up of the measurement
Pocket pulsar (for rate of decrease by the cycle)
Some cables
Discriminator
Fan in/out
Oscilloscope
Scalar
Hiroyuki Harada

4. The cycle of general measurement for PMT’s noise rates
Only this part is essentially different in case of measurement in IR. To next page.
PMT
Fan in/out
Discriminator
Scalar
For all measurement is the same conditions, the discriminator’s threshold values, which 30, 60, 200 and 1000 mV, must be set to a value shortly after PMTs output the signals.
After HV was turned on, we must wait for measurement more than 5 minutes for warming PMTs.
oscilloscope
The wave form for PMT’s signals was taken a photo by oscilloscope.
Hiroyuki Harada

5. The measurement for it in IR
Rate of decrease for signal by cable (PMT-before FEM) is 20%. Thus the discriminator’s threshold values, which 30, 60, 200, and 1000 mV, must be set more lower value than them of general measurement.
Air Flow -> On
HV of all channels -> On
Hiroyuki Harada

6. Standard of good or bad PMTs
Scale -> 10mVΩ, 4ns, Threshold -> -10mV, Participant -> 10s
Good
bad
Raise time about 4ns?
High rates about 1000 Hz on Th60mV?
Broad pulse?
Discharge pulse?
Hiroyuki Harada

7. Real data
Hiroyuki Harada

8. Final check list Did you measure under rate of decrease of cables?
Did you measure the same condition, which Air Flow – on and HV of all channels – on, in case at IR?
Did you take a respectively photo by oscilloscope?
Did you update the data xls file on back page? Then, Did you link the photo?
Did you compare with a data before measurement?
Hiroyuki Harada