[G8b_run] Fwd: g8b TOF paddles

[Franz Klein]

Brian,
I remember that a lot of TOF counters could not be properly calibrated, 
meaning the resulting 'mass' spectra were washed out. That should show up 
in these spectra on the TOF calibration page. I understand that this is a 
blow for multi-particle channels, unfortunately it is not sufficient to 
simply use the corresponding hit-based track because the resolution for 
those is not that great (besides, your probability plot (p.4) is not flat: 
are you working on corrections and/or did you include the TOF=0 events?).
For other channels the missing TOF counters were accounted for in the 
acceptance calculation.

We have similar problems with TOF calibrations in g9a, where we figured 
out the difficulties afterwards and let the students cut on those counters 
in their analysis programs.

Greetings
Franz

ps. any progress with DC alignment for g9b?

On Sun, 24 Jul 2011, Eugene Pasyuk wrote:

> From Brian.
>
> -------- Original Message --------
> Subject: 	g8b TOF paddles
> Date: 	Sun, 24 Jul 2011 22:29:47 -0400
> From: 	Brian Vernarsky <soulish at gmail.com>
> To: 	Eugene Pasyuk <pasyuk at jlab.org>
>
>
>
> Eugene, I have been subscribed to g8b_run but for some reason it will
> not let me send messages.  I have written this up to send to the list
> could you please forward it for me?  Thanks, Brian
>
> Hi all,
>
> I have recently started looking at g8b, the omega channel, and noticed
> that I am losing half of my signal to events that have at least one
> particle that hit a TOF paddle that was marked as bad in the cooking.
> The bad paddles are detailed on the g8b TOF calibration page as can be
> seen here: http://www.jlab.org/Hall-B/secure/g8b/TOF_CALIB/g8b_TOFcalib.html.
>
> I don't know much about the TOF calibration or the rationale behind
> excluding these paddles beyond what is on that webpage, but given that
> the paddles did record events, as can be seen in ced, it seems like it
> would be very beneficial to recook the data to recover these otherwise
> completely fine events, especially because it means we could almost
> double the statistics in certain topologies, omega being the only one
> I've actually looked into.
>
> I have written up a pdf showing the problem and showing some events
> that are lost due to this problem in ced to show that a particle was
> in fact detected and that we could perhaps recover the event.  You can
> find it at the following location:
>
> https://www.andrew.cmu.edu/~bvernars/g8_tof_prob.pdf
>
> Again let me say that I don't know anything about the TOF calibration
> that goes into the cooking and so if there are valid reasons for all
> these paddles to be excluded please let me know and I'll be happy to
> include that info into the Monte Carlo.  But if it possible to recover
> some of these lost events it seems worthwhile to look into it.
>
> Thanks for your time,
>
> Cheers,
>
> Brian
>
>

===============================================================
                   Franz J. Klein, Associate Professor
                   CUA, Department of Physics
                   Washington, DC 20064
   office: Hannan Hall 206          phone: 202-319-6190
   or: Jefferson Lab,CC F-243       phone: 757-269-6672
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