FINDING THE SINGLES RATE vs. VOLTAGE FOR YOUR PADDLES

 

Most of the tubes used for this project work best in the voltage range of 900-1300 volts. The singles rate will tell you the number of hits your paddle records in ten seconds.  A graph of these rates in combination with the efficiency testing will allow you to determine the best voltage for your photomultiplier tube.

 

1.     Insert a base and hook up one paddle to the electronics.

 

2.     Obtain a digital voltmeter.  Make sure the probes of the voltmeter are insulated and then insert the probes into the test holes of the base.  Using the dial on the base, adjust the voltage to 900 volts using the conversion table below.  (This is a good starting point for these tubes.)

 

3.     Turn the voltage on.

 

4.     You will need to run two or three trials of the singles rates of the muons through one paddle and find the average singles rate at that voltage.

 

5.     After calculating your singles rate, record the value and increase the voltage by 50 volts.

 

6.     Continue this procedure until the rate become so high that your board no longer responds.

 

7.     Prepare a graph of the number of hits vs. voltage.

 

8.     Follow this procedure for the other paddle(s).

 

Actual Voltage

Voltmeter Voltage Reading

 

Actual Voltage

Voltmeter Voltage Reading

900 V

2.31

 

1125 V

2.88

925 V

2.37

 

1150 V

2.95

950 V

2.44

 

1175 V

3.01

975 V

2.50

 

1200 V

3.08

1000 V

2.57

 

1225 V

3.14

1025 V

2.63

 

1250 V

3.21

1050 V

2.70

 

1275 V

3.27

1075 V

2.76

 

1300 V

3.33

1100 V

2.82