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Franz,<br>
<br>
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:<br>
<ol>
<li>Avoids additional material in front of the test counter.</li>
<li>The existing counters are already instrumented: no need to find
our own HV supply, cables, discriminators, etc., to set up our own
trigger counters.</li>
<li>The existing counters have a well-known and excellent time
resolution.</li>
<li>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.</li>
<li>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.</li>
</ol>
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.<br>
<br>
-Richard J.<br>
<br>
<br>
On 5/13/2010 4:18 PM, Franz Klein wrote:
<blockquote type="cite" cite="mid:Pine.LNX.4.64.1005131608080.23672@jlabl1.jlab.org">
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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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