[Halld-tagger] beam time in Hall B

[Richard Jones]

Franz,

Thank you for this update on the Hall B scheduling decision timeline.  
We will get our request in to the Hall B management within a couple of 
weeks.  With regard to our use of the tagger T-counters, the advantages 
of using those over setting up our own are the following:

   1. Avoids additional material in front of the test counter.
   2. The existing counters are already instrumented: no need to find
      our own HV supply, cables, discriminators, etc., to set up our own
      trigger counters.
   3. The existing counters have a well-known and excellent time resolution.
   4. The existing readout has a built-in left-right coincidence which
      gets rid of singles and has a well-known efficiency.  Setting up
      our own would require finding a pair of counters, timing them in
      and plateauing the counters -- not a problem if we need to do it.
   5. The T-counters have full coverage, so we do not need to be
      concerned with alignment with our device.  The tagger-OR is
      already configured in a tree that allows us to select an
      appropriate segment of the focal plane from which to pull out our
      trigger signal, or simply to use the OR of the lower 1/3 of the
      focal plane, etc.

In short, it would save us time and effort.  None of the above would be 
enough to argue to delay the run, if it were decided that running sooner 
would be more convenient for the manpower.

-Richard J.


On 5/13/2010 4:18 PM, Franz Klein wrote:
> Richard,
> there are 2 readiness reviews coming up at the end of this months:
> May 26: HDice target
> May 27: Two-Photon Exchange
>
> As I mentioned before, I don 't see the HDice target at the stage that it
> can be scheduled this fall: Primex will come first!
> Primex will use the (smaller) high-energy T-counters only. That means we
> could get output signals from T-counters 20 to 61 if we wanted.
> I have not fully understood your intention for using the CLAS T-counters
> for trigger purpose. Isn't it better to have a small counter close to the
> fibers?
> I guess that we can talk about the beamtest in some detail by early June.
>
> Greetings
> Franz
> ===============================================================
>                     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: 757-269-6671
> ---------------------------------------------------------------
>    

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