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calorimeter document
Dear all,
I have not read every line, but I would like to share some high level
observations with you.
Cheers elke
1. Introduction.
Alex i think it would be nice if possible to replace the colored plots in
fig 2 with the ones you did today for your talk with the bar at the side
showing the relations between the colors.
2. BCAL + Appendix
I see no mentioning of electronics at all. Neither TDC nor FADC.
Should there not be at least a small paragraph on what requirements on
resolution and dynamic range we have to the electronics?
No mentioning of assembly or so, this is different to the FCal section.
It is okay to do this, but looks a bit strange. We could refer to the
pre-brief material drawings on the BCal assembly.
SiPMTs:
=======
what ever we write the test should not immediately suggest to the reader
that we are still far away from a final solution especially this is a 100%
design review. This opinion can be easily created reading this some of the
sections from the report testing this first arrays. I think we have to
check this again carefully.
Carl, some of the remarks made in your talk by Elton, George and me should
maybe incorporated in the write-up. I think the plots from Elton showing the
trade off between dark current and pde to reach the desired low energy
threshold should appear somewhere.
One more remark of caution here. Regina and JLab have a agreement of
disclosure with Sensl are we allowed to show all we are showing in this
report taking into account this disclosure agreement? Just something to
think about.
3. Fcal:
okay here I don't know the version on the www is the last one. but don't
we want to show rates for the inner blocks? Maybe even a plot showing the
difference between the old FDC material and the new one.
For the FCAl we mention electronics and holding structures.
4. Simulation.
section 2.1: does noise not also influence your lower photon threshold.
It is not mention not a super big deal but important. In the
worst case say just say still under study.
section 2.2: just a remark the current SiPMTs would not allow a
100ns gate width. Actually if the plots from Elton on pde
vs dark rate appear in the document, it would be good to check
the current thresholds are close to the numbers from
this study. I think they are.
section 3.4
I think it would be helpful to label the peaks to show which one comes
from which part in the detector. I like a lot the plots on photon
conversion beni does always z vs r. they give an idea where the problem
areas are. I would include one in addition to figure 10.
section 3:
I think it would be really nice to have a summary table showing the energy
and time resolution you get fro the simulations of both calorimeters and
compare it with the once we get from beam and cosmic tests.
section 4:
fig 12 and 13 show the combination of all photons in an event to either
give a pi0 or a eta. You show also the chi^2 for the fit confidence level.
Does the result for the chi^2 not depend strongly on your assumptions for
the constrained mass fit. I think it would be good to list which
constrains have been assumed and what happens if you vary them.
One more question how are this plots looking if you just assume that the
single photon energies are the same in some error.
Is it obvious why the background shapes for the different pi0 and eta
combinations (FCAL, FCAL+BCAL, and BCAL) change?
section 4.2
I have to ask unfortunately the same question again I asked already during
the collab meeting.
Pythia generates everything which is can be produced by a 9 GeV photon.
It has no signal events in. Now you run your generator which is able to
generate exotic waves, with all their special properties.
You mix this to event classes with some ration like 10:1 Pythia to exotic
or 1:1 or ....
than you run your analysis and see you find your exotic wave. If yes
wonderful if not you can set a limit on your sensitivity.
Why are you allowed to remove signal like events from the Pythia
background. In real life / data you can not tell what are signal events
and what comes from QCD photo-production (I don't want to say exotics
are not QCD).
The section describing the eta-pi0 analysis on page 18
bottom and page 19 is a bit dense to really follow in detail. As it is
a very important analysis a bit more explanation would be helpful. I can
explain in more detail on the phone or ... what i think would be needed.
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