Re: slides for review

["George Lolos" <George.Lolos@uregina.ca>]

Hi Elton:

I looked over the slides you have for the BCAL and have the following
comments/questions/suggestions:

1.  On Slide 4, I suggest you list the thickness of 15.5 Xo as the
MINIMUM thickness since for most of the actual photons detected, it will
be significantly larger.

2.  On Slide 5 you quote as the spot size seen by a single readout
system at 15 degrees as 7.5cm/sqrt(12) as 130 ps.  I am confused by this
transformation.  You quote spot size but show timing.  I suspect that
you project the shower path at 15 degrees in six readout cells, you
correct for the number of photosensors (12) and use the actual
propagation time in the fibers to turn it into timing resolution. 
Right?  If yes, perhaps adding a couple of extra lines showing the logic
behind it will make it clearer to them.

3.  On Slide 6, the title should be corrected to read "Considerations".

4. On Slide 8, how does the 650 ps becomes 175 ps for MIP's?  Is the 650
ps the sigma per read-out?  I can't reproduce the 175 ps you show.

5.  On Slide 9, perhaps you should state that the sigma=200 ps is what
we have gotten with the present fiber-PMT combination but we expect to
do significantly better with BCF-20 and SiPM's.

Cheers,

George

>>> Elton Smith <elton@jlab.org> 03/17/08 7:25 AM >>>

Hi George and Zisis,

I have updated some of the slides on tof measurements for the Bcal for
the
upcoming review (GlueX-doc-1001) slides 4-9. Please take a look at them
and provide feedback. In particular, slide 6 is an attempt to justify
the
segmentation in depth. Do you have simulation pictures of a side view of
showers at different incident angles? Or figures that better illustrate
the point?

Thanks, Elton.




Elton Smith
Jefferson Lab MS 12H5
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Newport News, VA 23606
elton@jlab.org
(757) 269-7625
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