The dispersion (standard deviation) of the estimator of neutron flux number


by Scatterer
Tags: estimating, experimental error, neutron scattering, standard deviation, statistcs
Scatterer
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#1
Dec12-12, 04:32 AM
P: 2
Hello people, I think the problem what I have is well known in experimental physics. Hope, somebody can helps me, thanks in advance. Here is:

There is a source of neutrons with a flux of λ neutrons per minute, which you do not know and want to estimate. You open the detector for one minute and it counts N neutrons. The maximum likelihood estimator for λ would be N.
Find the dispersion (or standard deviation) of this estimator. What will it be for the limiting case N=0?

Looks like Poisson distribution, where λ isn't known.
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DrDu
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#2
Dec12-12, 05:32 AM
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Quote Quote by Scatterer View Post

Looks like Poisson distribution, where λ isn't known.
Yes, exactly. What is the standard deviation in terms of lambda for a Poisson distribution?
Scatterer
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#3
Dec12-12, 05:38 AM
P: 2
Standard deviation in terms of lambda is square root from lambda, but my event is different I think, have you any idea?

DrDu
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#4
Dec12-12, 07:27 AM
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P: 3,372

The dispersion (standard deviation) of the estimator of neutron flux number


I think this is the best you can get with just one measurement. To estimate an empirical variance would require at least two measurements.


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