crab cavity meeting
CERN, 3 December 2007
participants: R. Calaga, U. Dorda, M. Giovannozzi, Y.-P. Sun, R. Tomas, F. Zimmermann
(1) Crab-Cavity
Scenarios, Rogelio Tomas
Vertical crab cavities are attrative.
Small radius at 800 MZ: 17.25 cm
1 cavity per beam
separation between beams 19.4 cm
4 cm radius beam pipe where beams are separate
cavity shape can be adjusted
beta<0.5 km
horizontal crab cavity in IR4
beam1-beam2 separation in IR4: 40 cm
beta<300 m at present
Masamitsu is developing high-beta option which could have larger beta
need free space of ~10 m length
Rama: only 1 prototype if AES is building one;
issues with noise, only one beam, may improve experiment only for one experiment
phase 0: Testing
1 hor. CC in IR4, 0.7 sigma at 1 sigma_z
OR
1 or 2 vertical CCs in IR5
in the case of a single common cavity,
coupling between beams via the cavity could be a problem;
LOM damping not required
damp only
can be installed anywhere
010 fundamental-mode cavity is automatically smaller than the higher-order cavity
spoke-like cavity
phase 1:
global, delta CO~1.6 sigma_z at 1 sigma_z
can one increase cleaning efficiency at higher (i.e. 8) sigma?
phase 2:...
AES work is for prototype used in phase 0,
which can/will be the conventional type.
Rama presented flower shape 010 design (and spoke cavity scheme)
(2) LHC optics
results & crab-cavity simulations, Yi-Peng Sun
excellent summary of paper by Chao and Hoffstaetter
comments:
Figure 9 + 4 in contradiction to conclusion?
apply these formulae to LHC tunes and LHC parameters?
determine sideband strength by FFT of tracking data for crossing angle only, crossing angle and crab cavity, and crab cavity only; perhaps also for 400 and 800 MHz