[Halld-tagger] photon beam working group

[Hovane Egiyan]

Hi Richard,

I attached  pictures of the Hall B downstream alcove from 2011 beam test 
run in Hall B taken from
the preliminary report at the collaboration meeting in May of 2011 (page 
8 in Jones et al ,  GlueX-doc-1759).
The black box after the big flange with red HV cables is an identical 
twin of the beam profiler that
Elton's commissioning list included today. The Hall D active collimator 
at that time was riding on top of the
total absorption counter's translation table within a meter downstream 
from the beam profiler.
This beam profiler was present on the photon beamline just upstream of 
the active collimator the whole time during the test.
And that is in addition to the main CLAS target far upstream which must 
have been a few % of a radiation length.
Based on UConn analyses, the active collimator worked well in these 
conditions. Could you explain
why you are sure that the active collimator worked well in Hall B and it 
will not work in Hall D if there is
an identical profiler in the beamline upstream of it?

Hovanes


 From Elton's bullets with, I believe, your underlined comments:
1. Require profile monitor to be installed and operational -- _where? 
(cannot be upstream of active collimator)
_....
7. Compare with response of active collimator -- _cannot be done with 
profile monitor installed




_

On 11/11/2013 11:17 AM, Richard Jones wrote:
> Hello all,
>
> The photon beam working group meeting is taking place this morning at 
> 11:30EST.  A draft agenda has been placed on the wiki.  Please change 
> as needed.
>
> -Richard J.
>
>
> _______________________________________________
> Halld-tagger mailing list
> Halld-tagger at jlab.org
> https://mailman.jlab.org/mailman/listinfo/halld-tagger

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