M
mook Johnson
I'm working with a PMT in pule counting mode. NAI scintillator is connected
to the PMT.
I set the discriminator level to 60kEV with plenty of dynamic range above
that.
I'm measuring background counts at around 90 CPS long term average. We are
applying a Cs source that raises teh count rate to about 700CPS long term
average.
What the user wants to do is measure the background at 1sample/sec for 45
seconds then measure a 1 sample/second with the source for 45 seconds.
Subtract the mean of those two for use elseware.
the problem is that when the measurement is repeated there is a fairly wide
spread in the two averages taken.
What I would like to know is how to calculate the spread in the two
averages. given the same source is used and the background levels are the
same(no sources running around).
to the PMT.
I set the discriminator level to 60kEV with plenty of dynamic range above
that.
I'm measuring background counts at around 90 CPS long term average. We are
applying a Cs source that raises teh count rate to about 700CPS long term
average.
What the user wants to do is measure the background at 1sample/sec for 45
seconds then measure a 1 sample/second with the source for 45 seconds.
Subtract the mean of those two for use elseware.
the problem is that when the measurement is repeated there is a fairly wide
spread in the two averages taken.
What I would like to know is how to calculate the spread in the two
averages. given the same source is used and the background levels are the
same(no sources running around).