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Re: "On the Measurement of BCAL Photoelectron Statistics" paper



On Fri, 12 Oct 2007, Andrei Semenov wrote:

Dear Andrei,

I was wondering you could point me to the MC study corresponding to the photon
studies George showed in his talk and note from April
807-v1 	Brief review of the BCAL and SiPM systems

thanks elke



> Date: Fri, 12 Oct 2007 13:33:37 -0400 (EDT)
> From: Andrei Semenov <semenov@jlab.org>
> To: Richard Jones <richard.t.jones@uconn.edu>
> Cc: halld-cal@jlab.org
> Subject: Re: "On the Measurement of BCAL Photoelectron Statistics" paper
>
>
> Richard:
>
> There is a problem in your paper: you assumed that the energy deposition
> in the fibers from MIP muons is close to that from electromagnetic shower.
> I do not think it's quite correct.
>
> From your formula (2), the about 5 MeV energy deposition (from MIP muon in
> the fibers) should have resolution of
>
>  sigma_E = 0.06 * sqrt(0.005) = 0.0042 GeV = 4.2 MeV   (viz., 84% !!!)
>
> Simulation with FLUKA gives about 3.5 times less value (see the
> attachment).
>
> The origin of the difference is that in the case of MIP muon (i.e.,
> cosmics), we just have dE/dx loss but no electromagnetic shower
> (including NO big spread of the deposited energy over the space volume).
>
> So, the most of the "sampling" effects just can not be applied for cosmics
> analysis, that changes the conclusions of the paper a lot.
>
> Thank you,
> Andrei

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