#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 0.237 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

0 2 4 6 8 1 0 1 20 . 0 0

0 . 0 1

0 . 0 2

0 . 0 3

0 . 0 4

0 . 0 5

s m R

56m

0 2 4 6 8 1 0 1 20 . 0

0 . 2

0 . 4

0 . 6

0 . 8

s m T

566

m

ELEGANT model for nominal BURT

INJ DIP-01-04ST1 BPM 01

PRELIMINARY!!

NOT DEBUGGED

ST 1 EBPM 01 12.1479 0.05344141 0.8544566R56 (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 2012. 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 = 0.264• 3272, (Dec 2012). 3

measurements scanning up-down-up in energy – dE/dLC1GS =

0.266,0.277, 0.280

3058

3272

Infer from this that dE/dLC1GS has remained constant over second half of 2012

AR2 R56

0.04 0.03 0.02 0.01 0.01 0.02

10

12

14

16

18

Measure TOA on AR2-BPM-06 vs energyFirst time this has been measured

0.015 0.010 0.005 0.005 0.010 0.015

8

9

10

11

E st im at e S t an d ardE rro r t-S t at ist ic P-V alu e

a 8 .3 6 1 6 9 0 .1 1 9 0 35 70 .2 4 5 9 2 .4 6 0 8 3 10 7

b 56 .5 7 3 7 25 .7 5 5 2 .1 9 6 6 2 0 .0 9 3 0 029c 3434 .5 2 2 0 35 .1 1 .6 8 7 6 4 0 .1 6 6 7 53d 389 368 . 2 6 3 5 74 . 1 .4 7 7 2 6 0 .2 1 3 6 64

Could argue R56 is consistent with zero