[Bteam] BTeam notes and agenda, 2011-02-09

Wed Feb 9 12:36:00 EST 2011

BTeam --

Now that we're back to steady operations in CEBAF, we should concentrate on our strategic interests for the remainder of the run. There is not that much more time before the 6 month SAD, and we should develop our prioritized lists and study plans to learn what we need to learn before then. Machine-based optics/magnet measurements are foremost on my mind; other topics include motivations for diagnostic improvements. Please bring your ideas and priorities to the meeting this afternoon, and/or send 
them to me, and we'll develop our plans for BTeam for the remainder of this run. See you there, and thanks!

-Todd

  BTeam-2011-02-09

    1 2011-02-09 Wed 14:00 BTeam Meeting Agenda

      1.1 Optics-on-Call Report: Balsa/Alex => Shahid/Geoff

Yet another eventful week with a lot of operations diagnosis concentrating on the injector. On Friday we fixed the recent machine woes with a reduction of GSET on the 0L03-2 cavity in the injector to reduce fluttering PASKR (phase loop effort RMS). We have since been able to return to stable running conditions for Halls B/C, and with the addition of Hall A this week, we should be able to return to beam studies that do not involve immediate firefighting to keep the operational program on track.

      1.2 Beam Studies Report

        1.2.1 DONE Injector optics: Bogacz

Alex implemented a different injector optics last week, which also improved injector performance and reduced some trips in the middle of the injector chicane where beam sizes had previously been high. These optics should now be much closer to the design optics, as we also put these optics into the elegant design baseline.

        1.2.2 DONE Injector model: Freyberger

See above: elegant baseline should now match machine settings.

      1.3 Beam Studies Planning and Discussion

        1.3.1 TODO Bunch length measurement: Hofler/Kazimi

Lack of reliable bunch length measurements seemed to be a challenge during the diagnosis of the 0L03-2 problem. The most recent measurements did not seem correct. Perhaps we should make sure that this measurement is now reliable and understood. There is still a beam tail on the 1A SLM but there is no strong drive to change the injector or try to fix this based on experiment feedback and Compton/halo backgrounds.

        1.3.2 TODO ? Parity quality improvements from injector coupling: Roblin

ATLis 8346 <http://cebaf.jlab.org/atlis/task/8346>: Some concern that parity quality is marginal for Qweak. We should check that the injector skew correctors were scaled properly for the gun HV/energy changes during our optics fixes on 2011-02-03, and, if not, perhaps scaling them will improve Qweak parity quality with little impact. A measurement and retune, such as this ATLis from Yves, is fairly invasive.

        1.3.3 TODO ? LOCO Model Calibration Tests: Roblin (~2h)

ATLis 10700 <http://cebaf.jlab.org/atlis/task/10700>: Measured, but BPM problems in center of arc. Yves reported last week. Have some analysis upstream and downstream of affected mux, but should restore good BPM behavior and remeasure. Being worked on, will not ask for more time until sorted out. Noisy BPMs were vertical? Tief investigating, noted horizontal noise.

        1.3.4 TODO ? RayTrace in ARC3: Bodenstein (~30min)

ATLis 10708 <http://cebaf.jlab.org/atlis/task/10708>: See above, should redo with LOCO model remeasurement.

      1.4 AOB?

======================================================================

    2 2011-02-02 Wed 14:00 BTeam Meeting Agenda

      2.1 Optics-on-Call Report: Byung/Yves => Balsa/Alex

This has been a very eventful week with serious struggles to get high current operations back to hall C (1) and parity quality beam back to hall B (5) yet again. Optics have investigated injector optics and assisted with an observation of asymmetric quad settings in the injector chicane. Restoration of injector chicane quad symmetry helped restore high current beam operations on Mon 1/31 before it was again lost during gun HV=>130kV on Tue 2/1.

The majority of the BTeam meeting this week will focus on ideas for diagnosing the Hall C high current problem and restoring high current operations to Hall C. We are committed to moving forward with the 130 kV injector gun HV.

Upon restoration of routine high intensity operations, Hall C will likely want a spin dance (or mini-spin dance) and Compton cleanup, but these are second order compared to the first order problem of restoring reliable high-quality high-intensity beam.

        2.1.1 TODO Injector optics: Bogacz

Alex has different injector optics to discuss, and believes that the injector chicane quadrupole change on Monday is perhaps only the start of needed injector optics changes. (see hand notes)

      2.2 Beam Studies Report

        2.2.1 DONE? 5s Motion In Injector From Polling: Suleiman/Higgins (~1h)

ATLis 10739 <https://cebaf.jlab.org/atlis/task/10739>: Done AM Wed 2011-01-26, confirmed polling/vert motion correlation. Polling left off after study. Was originally observed about 1y ago. Seems to be someting within controls, as all polled items are downstream of first observed BPM 5s motion. Still noting 1s intermittent motion. Vector voltmeters entirely disconnected on 2011-02-01.

      2.3 Beam Studies Planning and Discussion

        2.3.1 TODO Injector optics: Bogacz

Alex has different injector optics to discuss, and believes that the injector chicane quadrupole change on Monday is perhaps only the start of needed injector optics changes. (see hand notes)

        2.3.2 TODO Injector model: Freyberger

The injector model is far from design and not correct right now, complicating comparisons to "design". How do we establish a good baseline injector model for the present machine configuration?

Discussion of Alex's talk seems to address this question as well.

        2.3.3 TODO Bunch length measurement: Hofler/Kazimi

Part of our problem is related to anomalous beam profiles as far back as Inj and arc 1 SLMs. Inj SLM is round, whereas design has a 1:3 x:y size ratio. Arc 1 SLM has two low energy tails that rotate with NL gang and individual cavity phases. NL individual cavity phasing did not improve this profile. This seems to suggest a bunch length issue.

Joe suggested that we calibrate the Hall C slit and close it up a bit to improve Hall C beam quality. This may tell us something about upstream timing/bunch length but may also make us more sensitive to upstream changes.

      2.4 Bunch length team meeting report: Kazimi/Hofler

    * DONE : Bunch length group meeting (Reza, Alicia, Tief)
      Can we make bunch length phase configurations SW config files? Done, very informally; discussed need for assembling tools. Can measure real-time bunch length with running 1-2 deg off crest in compensating directions in both linacs, assuming we can get back to that setup with high energy. Will discuss further.

      2.5 12GeV Pathlength Requirements Status: Tiefenback

        2.5.1 TODO Need conclusions document.

In process.

      2.6 AOB?

Author: Todd Satogata <satogata at Todd-Satogatas-MacBook-Pro.local> <mailto:satogata at Todd-Satogatas-MacBook-Pro.local>

Date: 2011/02/09 12:32:15

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