Difference between revisions of "PePPO NaI PositronDetector 4 JLab"
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Elapsed Time:6317 seconds | Elapsed Time:6317 seconds | ||
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| + | ===Run 1983=== | ||
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| + | Start a run using Co-60 | ||
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| + | The 1 MeV gammas appear near channel 500 like the Na-22 source. Perhaps I am not amplifying the PMT output enough to see the 0.511 gammas. | ||
==Gain== | ==Gain== | ||
Revision as of 15:37, 24 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
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.
Run 1982
Overnight Cosmic Run
Start Time : March 23: 16:01:47
End Time: March 24: 09:41:31
Elapsed Time:6317 seconds
Run 1983
Start a run using Co-60
The 1 MeV gammas appear near channel 500 like the Na-22 source. Perhaps I am not amplifying the PMT output enough to see the 0.511 gammas.
Gain
Linearity
Readout
F250
JLab's F250 flash ADC will be used to measure the NaI output