[Halld-tagger] Fwd: [New Logentry] To-do list for photon beam working group in Spring 2015 run

[Ken Livingston]

Hi Richard,
Thanks for sending that information.
Re. the polarized photon beam (item 3 on your list). I've been working 
with Hovanes (and latterly Paul Mattione) to get the slow controls in 
place. The plan with beam is approximately as follows:

Assuming stable beam is available before I arrive in Jlab (18th Arpil), 
we'll do some initial setup remotely on a VNC session + skpye. This 
would be done on an ad hoc basis in hours of UK daytime mon-friday, 
fitting in with other tests and priorities - enough to get one crystal 
aligned and demostrate that we have a working coherent brem setup. I 
would then do more some rigorous systematic studies of scanning and 
debugging of the tools for running and setting up coherent brem during 
my 4 night shifts 19-22 April. The tagger / microscope scalers are 
certainly needed for all of this. PS scalers would be desireable, since 
they'd let us see what get's through the collimator, as opposed to what 
hits the tagger.  Main triggers / PS triggers can be run during any of 
this time, but are not needed for the coherent brem setup. (Once it's 
set up, it would be good to run with the main trigger and demonstrate 
that we can get an asymmetry in a physics reaction)

The original plan had be to start this yesterday. It seems that the beam 
"may appear" on April 11th. Call me a pessemist, but I think there's a 
fair chance that we won't have a stable beam for doing the diamond 
studies until about the 18th, which coincides with my shift period. I'm 
happy to compromise / scale down expectations, depending on how much 
beam we actually get, and how this can be fitted in with the other 
planned activities. We'll just have to wait and see.

Regards,
Ken


On 01/04/15 23:12, Richard Jones wrote:
>
>
>   To-do list for photon beam working group in Spring 2015 run
>   <https://logbooks.jlab.org/entry/3331498>
>
> Lognumber 3331498 <https://logbooks.jlab.org/entry/3331498>. Submitted 
> by jonesrt <https://logbooks.jlab.org/user/jonesrt> on Wed, 04/01/2015 
> - 18:01.
>
> Logbooks: 	HDLOG <https://logbooks.jlab.org/book/hdlog>
> Tags: 	Beamline <https://logbooks.jlab.org/tag/beamline>
>
> Here is a short summary of the useful things that we would like to do 
> during this run if and when we get beam. It is a short list for a 
> short run. I can break it out into more pieces and add more details if 
> desired.
>
>  1. Collect an order of magnitude more statistics with the PS trigger
>     than we did in Fall 2014. At present, this means that we cannot be
>     taking main detector triggers at the same time. Perhaps moving
>     Alex Somov's trigger studies upstream of this may allow him to
>     introduce a new capability to run the two triggers simultaneously.
>     Under optimal beam conditions at 5.5 GeV, with the radiator
>     thickness and beam current adjusted to give a PS trigger rate of
>     600 Hz we estimate that our goal for this item would be reached in
>     6 hours of beam.
>  2. Vbias scans of the tagger microscope. For this, we do not need
>     dedicated triggers, but any beam with a radiator in would do. This
>     would be good to do during a period of trigger studies or
>     something like that where having the microscope partially disabled
>     would not interfere with the program goals. Each scan should take
>     about 30 minutes of beam, and we would like to request 3 such
>     periods initially. Given that it is only 30 minutes, it might be
>     reasonable to request the option of coming back again once these
>     data have been analyzed for one or two more scans near the end of
>     the run.
>  3. Engineering run with diamond radiators. Ken Livingston has
>     requested 3 shifts for initial setup and alignment, which probably
>     should not be back-to-back. Once the diamond is aligned, we would
>     like to take data with the PS trigger. Taking these data during a
>     period with stable beam will be a priority. A total of 10M
>     triggers with the diamond radiator and the PS trigger would be the
>     request. These could substitute for the 10M triggers in item 1, so
>     if all goes well we could get substantial overlap between item 3
>     and 1.
>
> Richard Jones
>
>
>
>
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-- 
=======================================================
Ken Livingston

Dept. of Physics & Astronomy,        Tel: +44 141 330 6428
University of Glasgow,               Fax: +44 141 330 5889
Glasgow G12 8QQ.
Scotland. UK.
=======================================================