LET: Meetings: Minutes for 2005 September 27

Attending: Representatives from LEPP, FNAL, LBL, and SLAC

Emittance Bumps and Adaptive Alignment: N. Solyak made presentations on these topics (see here and here). He improved the coefficients used in previous mat-LIAR simulations (the bump coefficients didn't result in adequately closed bumps) and studied a system with 2 dispersion bumps and 2 wakefield bumps. The dispersion bumps were generated with correctors, the wakefield bumps used movers for cryomodules. The bumps give good results for the standard misalignments and 2% precision of the beam size measurement. Nikolay has also looked at 5% precision and it also looks okay, he will report on this at a later date.

Adaptive alignment is a technique used to smooth the orbit in an initially-misaligned linac. Nikolay looked at implementing this in mat-LIAR and studying an ILC-like linac (but only 1/3 as long, since the simulation requires a lot of tracking and is computationally intensive). He found that in the presence of significant BPM offsets the emittance growth does not converge to as small a value as one would like; smaller offsets (such as what is obtained with BBA) may help.

Old Business: None.

New Business: The main linac aperture radii are around 35 mm, while the BDS has aperture radii around 10 mm. This has implications for the runaway beam ramp at the end of the linac -- does the kicker need to kick the beam out of a 10 mm or a 35 mm vacuum chamber? The latter is obviously harder! The aperture transition between linac and BDS is a topic that requires further study.

Next Meeting: Tuesday, 11-Oct-2005, 12:30 / 11:30 / 9:30.