Re: UPV region - photon detection (fwd)

[Elke-Caroline Aschenauer <elke@jlab.org>]

FYI

---------- Forwarded message ----------
Date: Tue, 16 Oct 2007 09:28:54 -0400
From: Matthew Shepherd <mashephe@indiana.edu>
To: Elton Smith <elton@jlab.org>
Cc: Alex Dzierba <dzierba@indiana.edu>, Paul Eugenio <eugenio@fsu.edu>,
     George.Lolos@uregina.ca, Zisis Papandreou <zisis@uregina.ca>,
     Elke Aschenauer <elke@jlab.org>, Curtis Meyer <cmeyer@ernest.phys.cmu.edu>,
     Richard Jones <richard.t.jones@uconn.edu>
Subject: Re: UPV region - photon detection


Hi Elton,

I'm not quite sure I see your geometry.  Do your wedges sit entirely
inside the BCAL, both in z and r?

This sounds similar to something Beni and I were talking about over
the summer.  I was thinking of a ring of wedges that would sit just
inside of the BCAL and downstream from the last FDC package.  The
inner surface of these wedges is cut at the angle from the target and
the thickness in z would be equivalent to ~15 radiation lengths or so
-- enough to contain a shower.

The ring has two advantages:

- It minimizes showers that clip the corner of the BCAL and spray
into the FCAL.
- It also collects conversions in the last FDC ring.

The big disadvantage would be that it might require a change to the
cabling scheme of the FDC.  Ideally one wants this ring to be pressed
right up against BCAL so the two work in unison as a single
calorimeter.  The FDC cables would complicate this.

Readout would need some work.  Downstream end readout is tricky
because of the taper.  Upstream end readout creates a gap between the
FDC and the wedge that is not so desirable.

Maybe we should spend some time at the collaboration meeting next
week to toss around some of these design ideas. If we come up with
something we like we should probably make the plunge and try to build
a GEANT model of it.  I think our neutral particle reconstruction
framework might be in good enough shape to be able to examine how
some of these gap sealing detectors might work.  (We're also at a
stage where we are starting to be able to understand the physics
implications of leaving the gap just as it is currently.)

-Matt


On Oct 16, 2007, at 9:12 AM, Elton Smith wrote:

>
> Hi all,
>
> One possibility for covering the gap between the bcal and the fcal
> would
> be to build wedge-shaped calorimeters about 25 cm long with the 5.3 cm
> base upstream and perpendicular to incident photons.  These wedges
> would
> be located at the downstream end of the barrel creating an inside ring
> that would collect photons that would otherwise clip the corner of the
> bcal.  The way to read this out would have to be upstream (i.e.
> photons
> would be incident through the readout, likely SiPMs).  In order to
> contain
> the showers as much as possible, the calorimeter should have a small
> Moller radius. A practical solution might be be to machine them out
> of the
> same scint-fiber-lead matrix used for the barrel.
>
> Comments/suggestions?
>
> Cheers, Elton.
>
>
>
>
>
>
>
> Elton Smith
> Jefferson Lab MS 12H5
> 12000 Jefferson Ave
> Suite # 16
> Newport News, VA 23606
> elton@jlab.org
> (757) 269-7625
>
> On Mon, 15 Oct 2007, Alex Dzierba wrote:
>
>> Dear Paul, George, et al
>>
>> Please see the attached note - your comments/suggestion most welcome.
>> I believe, based on these simulations and given the dearth of
>> manpower,
>> that we might want to review the cost/benefit of  instrumenting both
>> the current gap between UPV and BCAL and the the UPV region.
>>
>> Perhaps we can discuss at a future phone conference?
>>
>> Alex
>> --
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> Alex R. Dzierba
>> Chancellor's Professor of Physics (Emeritus)
>> Department of Physics / Indiana U / Bloomington IN 47405 /
>> 812-855-9421
>> JLab Visiting Fellow
>> Jefferson Lab / 12000 Jefferson Ave / Newport News, VA 23606 /
>> 757-269-7577
>> Home Phone: 812-825-4063  Cell:  812-327-1881  Fax: 866-541-1263
>> http://dustbunny.physics.indiana.edu/~dzierba/
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>