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Brief summary of run #10 (23-25 September) and plan for the rest of commissioning

Brief summary of run #10 (23-25 September) and plan for the rest of commissioning. Shinji Machida o n behalf of the beam commissioning team ASTeC /STFC/RAL 27 September 2010. Aims. Understand rf system Phase with respect to beam Vector sum voltage

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Brief summary of run #10 (23-25 September) and plan for the rest of commissioning

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  1. Brief summary of run #10 (23-25 September) and plan for the rest of commissioning Shinji Machida on behalf of the beam commissioning team ASTeC/STFC/RAL 27 September 2010

  2. Aims • Understand rf system • Phase with respect to beam • Vector sum voltage • Time of flight with +2 mm shifted lattice. • Closed orbit measurement and its correction. • Understand “improvement” by QD27.

  3. rf system (1)vector sum • When all cavities have the “same” phase • Observed syn period is 20 turns instead of 14. • A beam sees only a half of rf voltage, 0.5 MV. • When 10 cavities have the “same” phase and 9 cavities have the opposite phase • Observed syn period is 43 turns instead of 61. • A beam sees twice as much voltage, 0.11 MV. • Individual phase has to be set by using a beam.

  4. rf system (2)phase with respect to a beam • Global phase moves with respect to a beam once we use “sweep rf” button. • Necessary after trip. • Make it hard to determine individual cavity phase by single cavity excitation.

  5. rf system (3)measurement of individual phase • With all cavity turned on with 10 acc. and 9 dec. phase, change phase of only one cavity. • Can find zero crossing of the cavity. • Difficult to distinguish rising or falling edge. • Change individual cavity phase and monitor rf voltage of the cavity (Yuri). • Beam loading tells thephaseof crest. • Although it is tedious to find crest phase of the all cavities, it is the only promising way to determine individual rf phase.

  6. Lattice • With all the quadrupole +2 mm shifted outside, time of flight increased as expected. • There is enough aperture with 20.5 MeV/c equivalent momentum and the nominal QD/QF ratio. • Shifted quadrupole lattice helps to match rf frequency range (+1.5, -4 MHz) to ToF. • Issue is whether we still have enough move for COD correction. QD has +/- 2.6 mm move only.

  7. COD measurement and correction (1)method • Total 12 BPM cables are available. • 12H or V signalsatonetime. • Switch off the machine 3 times to measure the whole 42 cell BPM for horizontal COD measurement and another 3 switch off for vertical. • Seems the only way at least before shutdown.

  8. COD measurement and correction (2)preliminary result • Both horizontal and vertical COD at BPM between QD and QF are measured. • One set with QD27 with the same current as the rest. Another set with QD27 with 10% more current. • Preliminary results show COD of more than +/- 6 mm in horizontal.

  9. COD measurement and correction (3)correction • Attempt to correct horizontal COD. • David analyzing the data.

  10. Next step (1)main issues • Toward the demonstration of acceleration, two major (may be more) problems to be fixed. • Set individual cavity phase to maximum vector sum. • Correct closed orbit distortion. • Fixlattice for the demonstration. • 14.5 MeV/c is the minimum momentum? • Need quadrupole shift for the matching of ToF?

  11. Beam time (1) • Run #1: 20-23 June 2010 • Run #2: 12-15 July 2010 • Run #3: 27-29 July 2010 • Run #4: 3-6 August 2010 end of 4 sector • Run #5: 13-15 August 2010 full ring • Run #6: 18-24 August 2010rf commissioning • Run #7: 30 August – 2 September 2010rf available • Run #8: 7-10 September • Run #9: 15-18 September • Run #10: 24-26 September • Run #11: 2-3 October • Run #12: 10-13 October

  12. Beam time (2) • Run #11: Saturday 2 – Sunday 3 October • Both Shift 2 and 3 • Mark’s data taking in tomography section on 2 October. • rf on 2 October, but no rf on 3 October. • May have additional shift(s) on 4 October. • Run #12: Sunday 10 – Wednesday 13 October • Shift 2 and 3 on 10 October. • Shift 3 only from 11 to 13 October, but shift 2 may become available. • May have additional shift(s) on 14 October. • 6 to 8 days before shutdown in the middle of October.

  13. Next step (2)lattice for the demonstration • Probably not a good idea to shift quadrupole to make injection easier and to match ToF. • At least +/- 1 mm translation should be reserved for COD correction. • 1.301 GHz rf synchronizes with revolution frequency of 18.5 MeV/c lattice with QD/QF=205/196 A. • Is it possible to inject 14.5 MeV/c equiv. or lower beam without quadrupole translation? • Need to lower QF current?

  14. Next step (3)individual phase measurement • Measure individual cavity phase at the next shift with rf. • Beam loading measurement seems to work. • May need one or two shifts to measure the phase of 19 cavities and measure vector sum. • Main subject of 2 October.

  15. Next step (4)COD correction • Analyze measured COD and calculate individual quadrupole shift for correction. • May need several correction algorism. • Measurement of response matrix if necessary. • Main subject of 3 October.

  16. Next step (5)plan for the final week • With 18.5 MeV/c equiv. beam and QD/QF=205/196 A lattice, • Correct COD. • Scan global rf phase for capturing in a bucket and deceleration in serpentine channel. • Measure tune vs turn for plausible case. • With 14.5 MeV/c (or less) equiv. beam, • Measure and correct COD • Scan global rf phase for acceleration in serpentine channel.

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