Re: "On the Measurement of BCAL Photoelectron Statistics" paper (fwdfrom Zisis)

[Elton Smith <elton@jlab.org>]

---------- Forwarded message ----------
Date: Tue, 23 Oct 2007 08:40:08 -0600
From: Zisis Papandreou <Zisis.Papandreou@uregina.ca>
To: elke@jlab.org, semenov@jlab.org
Cc: halld-cal@jlab.org, richard.t.jones@uconn.edu
Subject: Re: "On the Measurement of BCAL Photoelectron Statistics" paper

Hello Elke:

the MC in GlueX-doc-807 came from Blake, and this was done before
Andrei's arrival at Regina.   The technique is referred to in
GlueX-doc-529 but that document does not include Blake's plots shown in
807.  There is no document that includes these; they are output of the
Regina Standalone Monte Carlo (ReSAM) that Rafael and Blake developed.
It is Geant-3 based.  This is the code that is still used for estimate
parametric behaviour of the BCAL (eg sampling fraction) to be used as
input for HDGEANT.  Blake had run several photon energies (using the
GEANT photon "gun") and several incident angles.  We have all these
plots in several GlueX-doc talks that George and/or I have given in the
last couple of years, and, of course, Blake has them on his computer.

At the meeting this week, George and I will show new information on the
following:
- photoelectron statistics addressing Richard's concern.  This analysis
has been largely completed by Andrei.
- information on the assumed starting point for no. of photons generated
per MeV of energy deposited.  The new effective number is smaller than
the traditional 8000 photons/MeV that manufacturers quote.

Andrei has updated his report on the cosmic muons and I will show his
stuff on Thursday.  We hope to have is report up on the portal as
GlueX-doc-845-v3 very soon, possibly before the meeting.

If these is additional info that you need, please let us know and we'll
get it to you if available.

Cheers for now, Zisis...

>>> Elke-Caroline Aschenauer <elke@jlab.org> 10/22/07 8:07 PM >>>
On Mon, 22 Oct 2007, Elke-Caroline Aschenauer wrote:

sorry, I forgot to mention for muon, so the same studies as in the note
but for muons.

thanks elke


>
> 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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 ( `,_' )+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=
  )    `\                                                  -
 /    '. |                                                  +
 |       `,              Elke-Caroline Aschenauer            =
  \,_  `-/                                                    -
  ,&&&&&V         Jefferson Lab                                +
 ,&&&&&&&&:       HALL-D 12C / F381       121-A Atlantic Avenue =
,&&&&&&&&&&;      Mailstop: 12H5          Hampton, VA 23664      -
|  |&&&&&&&;\     12000 Jefferson Ave                             +
|  |       :_) _  Newport News, VA 23606  Tel.:  001-757-224-1216  =
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   \_    |  |---' Tel.:  001-757-269-5352                             =
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