Re: draft document on using FM pmts for Bcal readout

["Christina Kourkoumeli" <hkourkou@phys.uoa.gr>]

Dear Elton and all,
I read your recent document on the FM read out.Let me make a few comments
since I will be unable to participate in Monday's meeting (I will be in
Bern for the ATLAS week).
Let first remind everybody that we have two 2" ones and we have performed
mesurements with them at 0.5T.The measurements (doc 712) show that if the
field lines are at about 45 degrees to the tube's axis,then there is NO
loss of gain (contrary to the 50%) which you quote in your first
paragraph.
Second point: 1x1 segmentation for the outer layers will be fine with a 2'
tube. Actually if one chooses a finer one then probably the measurement
will be dominated by statistical fluctuations on the too few photons out
there (see doc 731). Moreover, with the 1x1 segmntation the cost is not
prohibitive.
A final remark:these tubes are so robust thet they were used for the AMS
space experiment.
                       Cheers,
                      Christine
 >
> Dear collaborators,
>
> I have posted a draft document as GlueX-doc-1077. It still needs quite a
> bit of work, but has some figures and a table with initial results of
> light guide collection efficiencies which can be used to guide some
> discussions.
>
> Cheers, Elton.
>
> Elton Smith
> Jefferson Lab MS 12H5
> 12000 Jefferson Ave
> Suite # 16
> Newport News, VA 23606
> elton@jlab.org
> (757) 269-7625
> (757) 269-6331 fax
>