Revision as of 09:23, 23 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.
- Can the LLRF frame interval be changed? The sampling time looks fine, 200 Hz bandwidth is reasonable
- The dispersion at 703 can be measured directly (though there's not really any reason to assume it's different from theory):
- Vary momentum, steer back with dipole. This determines delta p as a function of delta GSET around the operating point without any effects from edge focusing (constant path length through the field).
- Then, apply a well-known delta p to move the beam off-center and measure the displacement with viewer and harp.
- Make sure 700 quads are at zero field! Consider degaussing, measure with probe
- Repeat MDLM504 degaussing test, measure profile w/ harp + viewer at 601, maybe 603, and 703.
- Measure FPS of recorded video for accurate time axis calibration