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Re: SiPM fiber test



> Hi All,
> it occurred to me that there is another correction one has to apply in
> order to get
> the mean number of photo electrons caused by electrons from a Sr90
> source when
> using a SiPM. I have put a draft  of a document I am writing about the
> fiber tests
> I do here at Jlab on the doc dtabase 1234-v1 where in section 2.2 I
> describe the results
> when I also use a SiPM.
>
> The spectrum of the SIPM with no Sr90 source can be viewed as random
> triggers, noise in the trigger PM
> and when a cosmic is going through the fiber. Both cases are independent
> of the Sr90 source trigger. That
> is the reason why I think one has to subtract the normalized background
> spectrum (normalized to time) from
> the Sr90 spectrum as Andrei did. But the resulting spectrum is still a
> convolution of the the Sr90 electron event with the
> dark rate of the SiPM which is to first order the background spectrum
> and hence on has to subtract the mean
> of the background Poisson distribution from the Sr90 source Poisson
> distribution.


YOU HAVE FORGOTTEN TO PUT ANOTHER "AS ANDREI DID" AFTER THIS SENTENCE TOO  :)



>
> After subtracting the background spectrum (no Sr90 source) from the main
> Sr90
> source spectrum the remaining spectrum is still a convolution of two
> Poisson distributions.
> Namely one from the light produced by the electrons from the Sr90 source
> and the other from
> the dark rate of the SiPM. Therefore, after extracting the mean number
> of photo electrons from the
> background corrected spectrum one has to subtract from this the mean
> number of photo electrons
> as obtained from the background spectrum alone.
>
>
> cheers,
> Beni
>
> --
> ***********************************************************
> Benedikt Zihlmann
> TJNAF
> HallD 12C/ F350
> Suite 8
> 12000 Jefferson Av.
> Newport News VA, 23606
>
> tel: 757 269 5310
> fax: 757 269 6331                zihlmann@jlab.org
> ***********************************************************
>
>