Difference between revisions of "PePPO NaI PositronDetector 4 JLab"

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Let's lower the gain of the Phillips 777 amplifier so the 511 peak is around channel 500.  This way the 1 MeV photons may come on scale.
 
Let's lower the gain of the Phillips 777 amplifier so the 511 peak is around channel 500.  This way the 1 MeV photons may come on scale.
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[[File:NaI_ADC1_R1979-R1980.png | 200 px]]
  
 
==Gain==
 
==Gain==

Revision as of 23:55, 23 March 2011

Detector setup for a NaI positron detector for PePPO

NaI detector

The PMT is powered by a HV supply which should have a DC ripple less than 200 mV peak-to-peak at 3kV/3mA. A DC ripple will change the gain of the PMT and cause the energy resolution to deteriorate.

The Linearity of the detector system is another way to reduce the energy resolution. The measured PMT output should be linear with the input signal when the gain is constant. This linearity can be measured using 2 radiation sources.


Input HV: +1085 V

Input Current: 2.362 mA


Running CODA: Running CODA

Measurements Using V792 QDC

Run 1979

Start Time : March 23:12:30:26

End Time: March 23: 13:10:47

Elapsed time: 2421 seconds

1979 NaI 1185Volts.png 1979 NaI ADCHist 1185.png

Run 1980

Remove Na-22 source from top of NaI crystal.

Start Time : March 23:13:11:23

End Time: March 23: 15:56:40

Elapsed Time:6317 seconds

Let's lower the gain of the Phillips 777 amplifier so the 511 peak is around channel 500. This way the 1 MeV photons may come on scale.


NaI ADC1 R1979-R1980.png

Gain

Linearity

Readout

F250

JLab's F250 flash ADC will be used to measure the NaI output

Na-22 source tests

Positrons#Experiments