[Bteam] notes from today's meeting

[Arne Freyberger]

  B-team Meeting Notes


    1 2009-11-18 Wed 14:00 Agenda--Notes

Realtime notes, no post-mortem editing or spin applied.


      1.1 Hall-A Compton and Accelerator issues ALL

Status report/discussion from Alex on Compton polarimeter and from 
Optics/Inj team on present status of the machine.

    * present signal to noise
    * discriminating between beam quality issues and physics issues
    * Open discussion of path forward
    * Summary
      Presently there is a low energy background. Hypothesis it is from
      synchrotron radiation.

      Photon detector collimator has been changed for PREX, so a compton
      at 6GeV with this collimator has never been previously established.

      Might be better to commission compton at lower energy.

      Compton works reasonably well at low current, but at high current
      the PMT cannot handle the low energy background.

      No real way to discriminate between physics related background
      (synchrotron radiation) and beam quality issues.

      There is a DAQ issue, something about old DAQ (which has a 3%
      error) but can operate at high current. The new DAQ was designed
      to achieve 1% error, but does not work at high current.

      Shielding and its effectiveness.

      New collimator will arrive next week, 2inches of Pb same aperture
      as previous collimator used for 5.9 GeV run.

      There has not been any optics tuning in the A line proper.

      Is the vacuum the source? No progress in improving the vacuum.
      Should the vacuum be purposefully degraded to see if the
      background gets worse.

      Dithering coils and modulation system is working.


      1.2 Hall-B beam size issues ALL

There has been some loss time due to establishing the required beam size 
?_x ,?_y < 150 ? m at the B target. Discussion and development of a 
trouble shooting guide for OPS

    * Summary
      Two different analysis routines, Halls and Accelerator, give
      different results.

      What is the source of the double hump? Would like to explore the
      source of the double hump by varying injector parameters.

      Double peaking should appear in all PMTs. Can this be programmed
      into the GUI to display all the data.

      Operations would like to see improvements to the harp analyzer, so
      that what OPS sees is the same as what the Halls are using.

      Operations needs more guidance on how to resolve this problem.

      Use an EPICS RECORD to pick the PMT that is used for the harp
      analysis.

      Perform scans at lower current.


      1.3 Viewer limited BPMs Tief

Proposal to adjust the timing of the viewer limited beam pulse so that 
the BPMs work during viewer limited mode.

    * Summary
      Viewer limited pulse is 10 ? s

      This will require better timing on BPMs?

      Delay viewer limited pulse.

      Take it up next week.


      1.4 FY10 projects ALL

Any thoughts on what Bteam wants to accomplish in FY10. There are two 
downs in FY10, Jan/Feb Winter down and the July/Aug Summer down.

    * Continue/complete BSY diagnostic suite?
          o viewers in front of dumplettes
          o move more harps?
    * Open to ideas
          o halo detector in BSY
          o finish the matching algorithm. Prove that our present
            diagnostics and software provide a good match which is
            verified by downstream harps.
          o Continue/finish ODR R&D in Hall-A
          o get undulator from Darsburry and put in a chicane. Can tune
            to different energies, so in the linac one can measure beam
            size of all five passes. Need a meter at the end of linac in
            12 GeV and a new vacuum chamber in the BCOM.
          o Replace 5 MeV dipole. Retain -12.5, -30 degree ports, and
            +12.5 or +30 degree ports. Magnet, vacuum chamber, power
            supplies. Horizontal gap is XXX? Does ISU have such a
            magnet? What are the field requirements? What are the space
            limitations?


      1.5 Optics-on-call

Outgoing
    Mike Spata, Geoff Krafft 
Incoming
    Alex Bogacz 

    * Program
          o Production running in A and B
          o Possible Compton optimization
          o Thaw the turkey

Date: 2009-11-18 15:45:00 EST

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-- 
Arne Freyberger
Director Operations Department
Jefferson Lab           Phone: (757) 269-6268
12000 Jefferson Avenue  Pager: (757) 584-6268
Newport News, VA 23606  Email:  freyberg at jlab.org

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