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Published byZechariah Johnsey Modified about 1 year ago

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AR1 BPM Calibration (for new electronics) Before any TOA measurements we attempted to look at the BPM calibration (AR2-BPM-03) Turn off quads (Q1,Q2) and sextupole and vertical corrector in first half of AR1. – The beam doesn’t seem to blow up. Then steer with AR1-DIP-01 to calibrate AR2-BPM-03 AR1-OTR2 all AR1 magnets ONAR1-OTR2 with AR1-Q1,Q2, SEXT VCOR-01 OFF

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AR1 BPM Calibration Change in AR1-DIP-01 current predicts poistion change at AR1-BPM-03 L_dipole = 510 mm, = 60°, 0 = L_dipole/60° = 490 mm, z (distance AR1-DIP-01 exit to AR1-BPM-02) = m Thus [ x/ I/I 0 ] predicted = 2.24 m

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AR1 BPM Calibration A nominal calibration is entered 20mm *(((A-P1)+(D-P2))-((B-P2)+(C-P1)))/ ((A-P1)+(B-P2)+(C-P1)+(D-P2))20 Bunch position varies over train (used 5 μsec train arbitrarily) Can look at BPM calibration for each bunch first bunchlast bunch Distribution of calibrations for all the bunches. Varies by about 8%. Expected value is (20% different to measured)

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Additional Info If we plot the calibration factor vs bunch number, rather than just a histogram of calibration values, we see a clear correlation. So this suggests the spread in calibrations is not statistical but systematic. Perhaps the best calibration value to take is around bunch # where the bunch position begins to plateau These bunches also give the best symmetrical range of x positions around x = 0. For the first dipole setting, x ~ - 7 ; for the last dipole setting, x ~ + 9 So if we take to be the measured calibration factor, and the real calibration should be -2240, then the calibration factor in the software should be changed from 20 mm to 23 mm.

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