EBPM kw achievements Kirsten Hacker

Summary Trombone fiducialization and characterization of hyteresis and backlash Accurate measurements of ACC1 energy changes and gun/laser phase changes with trombone feedback active Scan of coarse signal over larger range

Trombone group delay is 7.62 cm in data sheet Beam moves Distance -d VM moves Trombone moves -d d d d -2d For any beam movement d, The trombone moves 2d => Position = diff +trombone/2 7.62/2 = 3.82 cm BUT, the data only makes sense if you scale the trombone position with something closer to 15 cm because… Trombone Fiducialization

(um) 1.4mm/V Here 10 cm trombone length scaling used between end switches Scale according to signal wavelength NO Scale according to slope YES => multiply poti by 1.14/2 VM changeTrombone 0.95 mm1.35 mm 3 mm3.42 mm 7.2 mm5.79 mm 14.1 mm11.52 mm Doesn’t actually move here! Or here! 76 mm 29.2 mm 28.9 mm 27 mm 28.5 mm 29 mm 27 mm 1.6 mm/V Bump comes from reflection in pickup: changes location with beam position Trombone calibration is not constant over full range

Nevertheless, Measurement is reproducible And accurate with 15 cm trombone scaling PMT monitor EBPM Legend:

BUT! If *something* is jittering a lot, The fine measurement of the monitor cannot correctly calibrate itself and the measurements Are polluted by trombone hysteresis And inaccurate calibrations The situation can be improved through averaging and reducing the sensitivity of the trombone feedback

When the beam is jittering a lot, it is better to use the coarse signal option of the EBPM

Typical parasitic measurements PMT monitor EBPM

Machinedrift22.txt Trombone change at 46 hours Wonderfully invisible EBPMPMTVS EBPM PMT VS Correlation coefficients EBPMPMTVS EBPM PMT VS Drift over one setpoint