LET: Meetings: Minutes for 2005 July 05

Attending: Representatives from LEPP, FNAL, and SLAC

Brief reports from the laboratories:

Cornell: Jeff is working with a student and examining the impact of beam jitter on the various main linac steering algorithms. Another student is looking at BPM resolution as well as the possibility of using higher-resolution BPMs in some areas and lower resolution in others. They might attempt to study steering with broken BPMs and correctors. A third set of students is making progress using TAO to reproduce earlier studies of the bunch compressor.
FNAL: continuing to study the linac quad spacing configuration (see below).
LBL: Andy has completed the design of the 3rd generation 2-stage bunch compressor for Snowmass, which still needs to be put through the same set of studies as the previous 2 generations. He is working with Jeff and the TAO BC students.
SLAC: Glen is beginning to look at the BDS static tuning problem.

Old Business:

Kirti Ranjan at FNAL reported on work he and N. Solyak have done on the performance of DFS as a function of quad spacing. Unlike 1:1 steering DFS seems to prefer a stronger lattice. There are large emittance spikes in the upstream end of the lattice, and these are more pronounced for weaker lattices. Adding extra BPMs to the front of the weak lattice to manage the launch into the first DFS segment do not help; increasing the initial energy and thus reducing the initial fractional energy spread also does not seem to help. These issues have to be better understood. Kirti and Andy will look at the emittance growth for conditions corresponding to shorter bunches out of the compressor, or longer bunches going into the compressor.
PT at SLAC reported on further studies of the linac vertical arc (for the first set of studies, as well as Andrei Seryi's comments, see here and here, respectively). The non-closure of high order dispersion may introduce some difficulties and needs to be studied further, but other properties (chromatic beta, etc) seem to be fine.

Next Meeting: Tuesday, 19 July 2005, 12:30 / 11:30 / 9:30.