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Re: Calorimeter Review and Monitoring/Calibration
Hi Elke and Christina:
To what extent we worry about gain stability depends on what exactly we
expect the calibration/monitoring system to provide. If we want it to
provide us PRIMARILY with a diagnostic tool that all read-out cells are
operational and their relative timing remains as is (no major shifts),
then light output stability of any of the two systems Athens is pursuing
is not a critical issue. The gain of the SiPM's or PMT's can actually
be checked with data, for example with the prolific rho to pipi decay,
cosmics and perhaps some other channel. In such a scenario, LED's can
serve well as long as they do exhibit some reasonable stability as not
to alarm us on line if we notice a significant shift in gain of a few
PMT's/SiPM's. The only reasonable location, in my opinion, for the
LED's is for them to be secured on the light guides, all with the same
geometry for their respective light guides and on a flat surface. Both
the inner and outer layer light guides have such surfaces for small
LED's. Coupling on the WC is a no-no because minor variations in
location between units can have a significant effect on light reaching
the sensor and, in addition, we don't want to affect the index of
refraction of the WC-air interface.
If, on the other hand, absolute gain monitoring is a priority, the laser
system is an easier system to monitor relative to an absolute source,
for example an Am source embedded in a NaI-Scintillator system. The
laser system is also more robust in the long term because it's only one
source to replace.
Just my thoughts,
George
>>> Elke-Caroline Aschenauer <elke@jlab.org> 02/14/08 7:57 PM >>>
On Thu, 14 Feb 2008, Elke-Caroline Aschenauer wrote:
Dear Christina,
I looked through the slides in a bit more detail.
One question coming always up with all this calibration and gain
monitoring systems.
How stable are they. Do you have already some idea on the stability of
the
systems, like drifts per day or ....
Even if you measure "only" relative gain drifts, some reference
detectors are needed, did you already select some technology. In HERMES
we actually used 2 different types, just as a small reference
A gain monitoring system with Nd:YAG Laser for the Photomultipliers of
the HERMES experiment
H.Tanaka et al
Nucl. Instrum. and Meth. A 515 (2003) 725
The other question which might come up, where do we want to couple the
light in, in the photomultipliers / sipmts or in the scifi / lead-glass
or
in both. I know for the BCal we talked about coupling the light into the
winston cones.
I was just thinking one or 2 slides if at all possible on how the system
might be integrated into the detector layouts might be nice. But if
there
is no clear concept yet also fine, it is work in progress, so we have
not
to be 100% complete.
cheers elke
> Date: Thu, 14 Feb 2008 14:18:43 -0500 (EST)
> From: Elke-Caroline Aschenauer <elke@jlab.org>
> To: Christina Kourkoumeli <hkourkou@phys.uoa.gr>
> Cc: Alex Dzierba <dzierba@indiana.edu>, halld-cal@jlab.org
> Subject: Re: Calorimeter Review and Monitoring/Calibration
>
> On Thu, 14 Feb 2008, Christina Kourkoumeli wrote:
>
> Dear Christine,
>
> I just wanted to answer quickly, first of all thank you very very much
for
> the slides. I will go through them in a bit more detail tonight and
send
> you remarks if I have any.
>
> George, please don't include them in your talk, the slides are thought
as
> backup if we get questions. Such we are consitent with the FCal talk.
>
> One small remarks we will not print backup slides, apart from we get
an
> explicit request to do so.
>
> Cheers and thanks to everyboody
> elke
>
>
> > Date: Thu, 14 Feb 2008 15:39:11 +0200 (EET)
> > From: Christina Kourkoumeli <hkourkou@phys.uoa.gr>
> > To: Elke-Caroline Aschenauer <elke@jlab.org>
> > Cc: Alex Dzierba <dzierba@indiana.edu>, halld-cal@jlab.org
> > Subject: Re: Calorimeter Review and Monitoring/Calibration
> >
> > Dear all,
> > please find attached a few slides about the calibration+monitoring
system.
> > Good luck with the review,
> > Christine
> > > On Wed, 13 Feb 2008, Alex Dzierba wrote:
> > >
> > > Dear Alex,
> > >
> > > I know and I have asked Christina to generate slides on the
calibration
> > > system we are currently studying, so we can use them if the
question
> > > comes up. Beni will prepare a slide as backup addressing showing
the
> > > calibration system of radphi and E852, this show we have even 2
solutions
> > > for the FCal if the common system for FCal, Bcal and Tof would not
work.
> > >
> > > cheers elke
> > >
> > >
> > >
> > >> Date: Wed, 13 Feb 2008 08:32:59 -0500
> > >> From: Alex Dzierba <dzierba@indiana.edu>
> > >> To: halld-cal@jlab.org
> > >> Subject: Calorimeter Review and Monitoring/Calibration
> > >>
> > >> Hi All
> > >>
> > >> I just realized that neither the Calorimeter CDR document nor
> > >> the BCAL/FCAL talks address the issue of monitoring and
calibration.
> > >> This is a natural question for the reviewers to ask and we should
> > >> address it.
> > >>
> > >> 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://www.dzre.com/alex
> > >> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > >>
> > >
> > > ( `,_' )+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=
> > > ) `\ -
> > > / '. | +
> > > | `, Elke-Caroline Aschenauer =
> > > \,_ `-/ -
> > > ,&&&&&V Jefferson Lab +
> > > ,&&&&&&&&: HALL-D 12C / F381 121-A Atlantic Avenue =
> > > ,&&&&&&&&&&; Suite 8 Hampton, VA 23664 -
> > > | |&&&&&&&;\ 12000 Jefferson Ave
+
> > > | | :_) _ Newport News, VA 23606 Tel.: 001-757-224-1216
=
> > > | | ;--' | Mail: elke@jlab.org Mobil: 001-757-256-5224
-
> > > '--' `-.--. |
+
> > > \_ | |---' Tel.: 001-757-269-5352
=
> > > `-._\__/ Fax.: 001-757-269-6331
-
> > >
+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+
> > >
> > >
> >
>
> ( `,_' )+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=
> ) `\ -
> / '. | +
> | `, Elke-Caroline Aschenauer =
> \,_ `-/ -
> ,&&&&&V Jefferson Lab +
> ,&&&&&&&&: HALL-D 12C / F381 121-A Atlantic Avenue =
> ,&&&&&&&&&&; Suite 8 Hampton, VA 23664 -
> | |&&&&&&&;\ 12000 Jefferson Ave +
> | | :_) _ Newport News, VA 23606 Tel.: 001-757-224-1216 =
> | | ;--' | Mail: elke@jlab.org Mobil: 001-757-256-5224 -
> '--' `-.--. | +
> \_ | |---' Tel.: 001-757-269-5352
=
> `-._\__/ Fax.: 001-757-269-6331
-
>
+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+
>
>
( `,_' )+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=
) `\ -
/ '. | +
| `, Elke-Caroline Aschenauer =
\,_ `-/ -
,&&&&&V Jefferson Lab +
,&&&&&&&&: HALL-D 12C / F381 121-A Atlantic Avenue =
,&&&&&&&&&&; Suite 8 Hampton, VA 23664 -
| |&&&&&&&;\ 12000 Jefferson Ave +
| | :_) _ Newport News, VA 23606 Tel.: 001-757-224-1216 =
| | ;--' | Mail: elke@jlab.org Mobil: 001-757-256-5224 -
'--' `-.--. | +
\_ | |---' Tel.: 001-757-269-5352 =
`-._\__/ Fax.: 001-757-269-6331 -
+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+