Re: purposefully modifying a distribution to get...?

[Stefan Jeglinski <jeglin@4PI.COM>]

> Is the data removed in a non random manner?

Yes. Since the problem occurs at finite array boundaries, any pulses
removed will be clumped around those boundaries in time. IOW, if an
array is 500 units long, and a pulse is on the order of 15 units
long, one would find, at time 500, 1000, 1500 (etc) enforced
deadspots of up to 30 units wide, depending on exactly how 1 (or 2)
pulses overlapped the boundary.

Of course, the pulse processor itself can enforce dead spots in the
data stream of much larger than 15 units because of pulse pileup,
especially at high count rates, but those deadspots can occur
anywhere.


> e.g. a finite resolving time causes poisson time data to be skewed
> (I wrote this a few days ago, including the error functions)

Are you referring to the thread "counts in an interval"?

>   If I understand your apparatus (pulse pile up is eliminated by removing
> coincidences):  if the pulse height and the arrival times of the
> pulses are independent, I don't think it will matter.   Otherwise
> you PHA will be incorrect.

They are independent in the sense that in any particular interval,
one cannot predict if the pulse will be an "iron" one or a "copper"
one. One can only try to predict (via a Poisson process) that there
will be "a" pulse. Is there a more rigorous definition of
"independent" here?

To return to the dice analogy: if I roll the dice and then flip a
coin to decide whether the keep that datum, this is -roughly-
analogous to what the pulse processor does (-any- particular pulse
may or may not be kept depending on pileup). Whereas I am insisting
on flipping the coin only once every 10 throws (but -always- every
10th throw), to determine whether to throw the 10th, 20th (etc) datum
away.


Stefan Jeglinski