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#3271

#3271. Sat 08-Dec-12 . R56 Injector – BC2 GS calibration. First calibrate BC2 1. Start with beam in centre of screen INJ-5. Read INJ-DIP-01 current and convert to energy using magnet table 2. Increase BC2 gradient a little

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#3271

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  1. #3271 Sat 08-Dec-12

  2. R56 Injector – BC2 GS calibration • First calibrate BC2 • 1. Start with beam in centre of screen INJ-5. Read INJ-DIP-01 current and convert to energy using magnet table • 2. Increase BC2 gradient a little • 3. Bring the beam back to the centre of INJ-5 by increasing INJ-DIP-01. Convert new dipole current to energy using magnet table • 4. Repeat steps 2 to 3 several times so as to check linearity.

  3. R56 Injector – BC2 GS calibration • 1 unit increase in BC2 GS increases beam momentum by 0.237 MeV

  4. Injector Path Length vs Energy • Use ST1-BPM-01, ¾ length stripline • Measure time of signal by 50% level of peak Relative path length (mm) vs fractional momentum change

  5. R56 Injector Refine • Try to measure R56 for each setting. Restrict data to parabolic section around dp/p = 0 “R56” varies considerably !! 5 to 136 mm

  6. Analysis of nominal injector ELEGANT model for nominal BURT • Just take parabolic part of data for nominal BURT Relative path length (mm) vs fractional momentum change PRELIMINARY!! NOT DEBUGGED R56 (m) T566 (m) ST1 BPM 01 INJ DIP-01-04

  7. Analysis of nominal injector • Agreement between model and measurement not too exciting. • But, as the measurements show, injector path length quite sensitive to quad values (and thus quad degaussing). • Also, in simulation, if I change INJ-QUAD-05 from 1.53 A to 1.63 A and INJ-QUAD-10 from 0.70 A to 0.75 A, I get R56 ~ 0.02 m and T566 ~ 1.20 m • Also, more complications, could R51, R52 play a part? if booster exit trajectory is changed as BC2 gradient changes?

  8. Dispersion Around Machine • Nominal set up, in which AR1-SEXT-01 is ON. • Note relatively small dispersion at AR1 exit and AR2 entrance

  9. Dispersion Around Machine • With AR1-SEXT-01 off to see how this affects things • Note relatively large dispersion at AR1 exit and AR2 entrance

  10. Dispersion Measurement Issues • LC1 GS calibration was last measured carefully on #3058 at end of July 2012. Yuri measured LC1 GS on the shift after ours. Q. Any difference? A. Not significantly (see next slide). • There isunresolved uncertainty in the BPM calibrations which also affects the dispersion value.

  11. LC1 GS Calibration 3058 • 3058, (July 2012). dE/dLC1GS = 0.264 • 3272, (Dec 2012). 3 measurements scanning up-down-up in energy • dE/dLC1GS = 0.266,0.277, 0.280 Infer from this that dE/dLC1GS has remained constant over second half of 2012 3272

  12. AR2 R56 Measure TOA on AR2-BPM-06 vs energy First time this has been measured Could argue R56 is consistent with zero

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