Revision as of 15:42, 30 November 2021 by Bruker
- Harp axis calibration does not matter: It only changes the measured emittance but not alpha/beta, and its effect does not depend on the quad in use.
- Adding reasonable quadrupole moments to correctors is not enough to explain the inconsistency. It would need an extra quad with K1 ~ 5.
- At dp/p = 1e-3 (which is higher than what we observe unless the measurement is flawed), seeing significant inconsistencies in the quad scans needs a dispersion of many cm. In y, the only dispersion in this part of the lattice should come from the earth's field; this gives about 8 mm at the harp, much too low to see anything.
For future study
- Provided the BPMs work at all, we can use the 701 and 702 BPMs to better measure the momentum jitter. The CW waveforms give time-domain data in 900-microsecond-long windows with 16384 samples each, i.e., ~ 18 kHz sampling rate, 9 kHz analog bandwidth. More than enough to see all peaks, maybe even a little much to resolve them well. The only problem is, we can only run 100 nanoamps CW into that line. See if that's enough to see anything.
- Current picture of ITVM703: Take video to denoise
- using 703 harp, measure momentum spread vs. something interesting, e.g., buncher amplitude
- sigma values from Harp Fitter, so scaled correctly
- 100 nA avg. beam current
- RM11GSET=2.0, RM12GSET=9.95
- 23:09:25 GSET=34 sigma=0.48 mu=57.38
- 23:15:32 GSET=35 sigma=0.50 mu=55.53
- 23:16:42 GSET=36 sigma=0.56 mu=56.27
- 23:18:04 GSET=37 sigma=0.61 mu=56.20
- 23:19:13 GSET=38 sigma=0.75 mu=57.20
- 23:20:27 GSET=39 sigma=0.98 mu=57.05
- 23:21:42 GSET=33 sigma=0.51 mu=57.89
- 23:22:55 GSET=32 sigma=0.57 mu=57.80
- 23:24:16 GSET=31 sigma=0.63 mu=57.54
- 23:25:32 GSET=30 sigma=0.73 mu=57.53
- 23:26:44 GSET=29 sigma=0.80 mu=57.48 (not Gauss)
- 23:27:50 GSET=28 sigma=1.04 mu=57.01 (not Gauss)
- Ascertain harp data calibration without factor sqrt(2). How to test this?
- AHA! Harp Fitter appears to scale the fitted sigma down by sqrt(2), but the measured raw data are not affected. This means the position is most likely not scaled correctly. Check with Dennis.