[Halld] Run update and plan for the next days

[Alexandre Deur]

A correction to my email below: for the high current test in Hall A, it was (evidently) microA, not nA.

Thank you,
 
Alexandre Deur, Hall D Run Coordinator.
 
RC cell: 757-383-5542
Office Phone: 757-269-7526

----- Original Message -----
> From: "Alexandre Deur" <deurpam at jlab.org>
> To: "halld" <halld at jlab.org>
> Sent: Thursday, December 17, 2015 4:32:49 PM
> Subject: [Halld] Run update and plan for the next days

> Dear Collaborators,
> 
> Accelerator has been delivering beam to Hall D for a few days, although
> intermittently. We first got some beam on Monday, Dec. 14th. This was the first
> 12 GeV beam in Hall D, an important Accelerator milestone. After calibrating
> the ions chambers protecting our tagger equipment, we checked the beam quality.
> Radiation levels are about 5 times higher than what was seen with the 10.5 GeV
> last year. It is believed that this comes from a beam halo. However, these
> levels are acceptable for the type of works we will be doing during this period
> of commissioning. On the other hand, the beam position jitter is good: Hovanes
> wrote a program to provide an online analysis of the profiler data and the fast
> Fourier transform shows a x-jitter below 100 micron and a y-jitter of about 400
> micron. Later on Monday, Eugene and Nathan optimised the beam position for
> maximum photon transition to the Hall. Following this, Alex Somov started to
> set-up the pair spectrometer trigger and we took data w!
> ith the PS together with the microscope, hodoscope and TRD (Lubomir and Sergey's
> transmission radiation detector). Alex Somov and Nathan then did some hodoscope
> High Voltage scans. Meanwhile, Sergey took and analysed TRD data and those look
> good.
> 
> Tuesday and Wednesday, we did not get the beam. RF separation to allow
> multi-hall operation was being commissioned. In addition, accelerator went on
> to achieve another milestone: high current 11 GeV beam to Hall A for several
> hours (~70 nA, 800 kW). The power of the RF separating cavity turned out to not
> be enough to separate the A and D beams so the beam transport was modified in
> order to facilitate the separation. This was successfully done. However, a fast
> shutdown system fault prevented to run with CW beam. This fault was fixed this
> morning and multi-hall operation should be now possible.
> 
> Meanwhile, the Hall D fast feedback commissioning, which was planned to start as
> soon as good beam is established in Hall D, had to be postponed to Thursday
> because of software problems.
> 
> Today, Thursday 17th, we got the beam back early in the morning. But it was
> intermittent (for owl shift, we got in total 50 min of beam in packages of few
> minutes). The electron beam is also scrapping somewhere. The lower beam quality
> was traced back to the change of beam transport done in order to allow RF
> separation. After this optic change, the beam transport matching in the Hall D
> line had not been done. The rematching was done this morning.
> During the morning and beginning of afternoon, Alex Somov worked on the main
> detector trigger while accelerator started to commission the nA BPM. In the
> same time, radiation monitor data at different current and radiator thickness
> were also taken by Mark Ito and Eric in order to assess the beam quality.
> 
> The nA BPM commissioning quickly ran into software issues. Since the person
> responsible for it is busy with the (higher priority) commissioning of the fast
> feedback, we will most likely not be able to continue the nA BPM commissioning
> during the Fall 15 run.
> 
> We are now starting the fast feedback commissioning. Its first phase should last
> until 6-7pm. Then, accelerator will try to provide beam to Hall A and D. If
> this fails, Hall A will get the beam tonight, with the understanding that Hall
> D runs this week end. If the separation is successful, Alex Somov will finish
> the main detector trigger setup. Then Sergey Furletov will start studying the
> DAQ performance. If we have time, we will take pi0 calibration data tonight. We
> will continue with the same program tomorrow, with in addition some bias
> voltage study for the microscope.
> 
> Thank you,
> 
> Alexandre Deur, Hall D Run Coordinator.
> 
> RC cell: 757-383-5542
> Office Phone: 757-269-7526
> 
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