#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 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.

R56 Injector – BC2 GS calibration 1 unit increase in BC2 GS increases beam momentum by MeV

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 INJ-Q06 Changed from 0.7 to 0.8A Nominal BURT INJ-QUAD10 changed from 0.7 to 0.8 Repeat Nominal BURT

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

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

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?

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

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

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

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

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