[Bteam] BTeam notes and agenda, 2011-02-16

[Todd Satogata]

BTeam --

Here are the notes from last week and the moderately long agenda for this week. As usual, 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-2011-02-16


    1 2011-02-16 Wed 14:00 BTeam Meeting Agenda


      1.1 Optics-on-Call Report: Shahid/Geoff => Todd/Jay

At last at least a moderately quiet week, though with some position parity issues to be worked out for Hall C/Qweak. This included an investigation of injector match through the injector chicane into NL, which seems to still be questionable.


        1.1.1 DONE Check quad ranges/procedure for injector match multiharp

Arne questioned last week: Does multiharp have good quad ranges for match? Need to collect multiharp data and return to injector match procedure. This includes getting hardware for harps back in working order. RonL notes that harp repair wants an injector access. This was checked and adjusted during below Tue 2011-02-15 studies by Jay.


        1.1.2 DONE Check injector skew quad scaling and setup

Yves noted last week that we should check skew quads, particularly whether they were scaled properly for 6.3 MeV and lemi work. This was likely done as part of check and measurement to 100 keV during 2011-02-15 Tue beam studies by Yves.


      1.2 Beam Studies Report


        1.2.1 DONE Multiharp, injector optics match into NL: Jay

Data and attempt at rematch acquired 2011-02-15 Tue, but rematch seemed to make conditions worse.


        1.2.2 DONE Measure injector transport across capture, 1/4: Yves

ATLis 9622 <http://cebaf.jlab.org/atlis/task/9622>: Some data acquired 2011-02-15 Tue. Do we need more data for the downstream section of the injector?


        1.2.3 New injector optics review: Alex

Alex will briefly review the high points (including dispersion through the chicane, and modified optics for diagnostics) of the injector optics installed 2011-02-03 Thu.


        1.2.4 DONE Injector model: Arne

Elegant baseline should now match machine settings. Jay: Are these values consistent with those used by matchElengant?

    * TODO Check consistency. If not, make consistent and achieve consensus.


      1.3 APEL Hall Liason Comments


      1.4 Beam Studies Planning and Discussion


        1.4.1 TODO Raytrace/Multiharp in HallC/Qweak: Jay/Ryan/MikeT

Investigate optics/transport of response to modulation coils at 3C08/10 and FFB coils at 3C04/06/07. Requires beam to hall C and may disrupt beam to other halls depending on where the the measurement is launched.


        1.4.2 TODO Bunch length measurement: Alicia/Reza

Need to check harp status before measurement. Both 130 kV normal and backphase bunch length measurements should be performed before 6 month SAD. 4D00 spectrometer PS was reinstalled 2011-02-10 Thu.


        1.4.3 TODO Parity quality improvements from injector coupling: Yves

ATLis 8346 <http://cebaf.jlab.org/atlis/task/8346>: Some concern that parity quality is marginal for Qweak. A measurement and retune, such as this ATLis from Yves, is fairly invasive. Can be checked in ~10min with 30Hz PZT; this is a backup plan in case PZT/other injector measurements are inconclusive.


        1.4.4 TODO LOCO Model Calibration Tests: Yves/Ryan/MikeT (~2h)

ATLis 10700 <http://cebaf.jlab.org/atlis/task/10700>: Measured, but BPM problems in center of arc. 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.


        1.4.5 TODO RayTrace in ARC3: Ryan/MikeT (~30min)

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


      1.5 AOB?


        1.5.1 TODO Injector configuration documentation: Reza

Document proper operational injector configuration (6.3 MeV energy, crested within 5 degrees, etc): Reza et al


        1.5.2 TODO Plan 1-pass A/C split, B offline (probably) for Feb 25 (Yves/Jay)

What resources/beam time do we need to be prepared?

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


    2 2011-02-09 Wed 14:00 BTeam Meeting Agenda


      2.1 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.

Alex: Thursday optics was particularly productive (see below). 2h into optics work, spots improved/reproduced. Also modified model for existing 6.3 MeV injector rather than old 5 MeV, and Jay prepped new GSETs for cavities to include end-field effects. Geoff: Do we have good procedures? Alex believes we're in good shape there.


        2.1.1 TODO Arne: Does multiharp have good quad ranges for match? Need to

collect multiharp data and return to injector match procedure. This includes getting hardware for harps back in working order. RonL notes that harp repair wants an injector access.


        2.1.2 TODO Yves: notes that we should check skew quads, particularly

whether they were scaled properly for 6.3 MeV and lemi work.


      2.2 Beam Studies Report


        2.2.1 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.


        2.2.2 DONE Injector model: Freyberger

See above: elegant baseline should now match machine settings. Jay: Are these values consistent with those used by matchElengant?

    * TODO Check consistency. If not, achieve consensus.


      2.3 Beam Studies Planning and Discussion


        2.3.1 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.

Do we expect bunch length measurement to work at 130 kV? Reza says yes, but this requires desk time and some operations time. This is a priority to get working before the 6 month SAD since we also return with the gun at 130kV. Temperature stabilization may also have helped stabilize this effort, but picture and procedure -- it was the beam and stability that were bad.

Backphase bunch length measurement at 130kV is also a priority before the 6 month SAD. We have not yet checked the harps necessary for this measurement, should check those at first opportunity. This at 4D00, requires spectrometer PS back in, which should be done 2011-02-10 Thu AM along with change back to longitudinal polarization for Qweak.


        2.3.2 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. Can be checked in ~10min with 30Hz PZT, should still work.


        2.3.3 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.


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

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


      2.4 AOB?


        2.4.1 TODO: Document proper operational injector configuration (6.3 MeV

energy, crested within 5 degrees, etc): Reza et al


        2.4.2 Jay: C Compton scintillator adjacent to beamline noise spikes,

per elog entry. 100s intervals, per elog entry last night. Compton photon detector also modified, so comparisons to previous expectations difficult. Hall C will perform access to switch back to old detector electronics.


        2.4.3 TODO Add hall liason reports to BTeam agenda (Todd)


        2.4.4 TODO Add MikeS to list (BSY/Recombiner measurements) (Todd)


        2.4.5 TODO Plan 1-pass A/C split, B offline (probably) for Feb 25 (Yves/Jay)


        2.4.6 Update on path length (Tief): annual thermal cycle, machine bigger

in summer, smaller in winter, so doglegs take up slack more in winter than summer. 12 GeV heat loading will dominate arcs, about half of total machine length. Concrete has dirt/water outside, and will have heating resistors on walls. Calculations for 1C temp change is about 3.5 degrees of RF phase. (3.5deg/C) Surrogate meas was to raise water temperature, saw about 2F~1C temp rise at surface of concrete; pathlength changed about 6deg cumulative around machine. After dogleg compensation, they got 
a number closer to 5.5deg, all from east arc (minus arc 9), or about 1.5deg/C/arc. This about half of what one would expect from the naive/simple thermal argument. Questions about whether we saturated the temperature rise; also only did half the planned temp rise because of caution about hoses. Measurement was same order of magnitude, hence concrete heating contribution to pathlength is a plausible mechanism. Observation of pathlength change is also consistent with similar pathlength change in 
all east arcs.

Multiyear pathlength drift drives possible need for additional pathlength compensation. We've exhausted previous capabilities, which is why we need to take up slack now in arc orbit pathlength changes.

Consensus seems to be that we should increase dogleg capability by momentum change for 12 GeV plus taking up arc slack -- nearly. The open question is whether the upper bound of the cooling water heating test is the additional dogleg capability that is needed.

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

Date: 2011/02/16 10:24:41

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