Accelerator Physics Group Meeting

09/12/01

Present: J. Wei, J. Galambos, S. Henderson, D. Jeon, S. Aleksandrov, 
S. Kim, M. Doleans, S. Cousineau

The main focus of the meeting was on the upcoming ASAC meeting. concern was 
expressed over the present end-to-end simulations that show considerable 
halo developement, whn the beam is tracked through the MEBT. Inclusion of 
jitter will result in excessive foil miss.

A question on the longitudinal stability of the beam n the ring arose. 
Numerical simulations by Holems and Woody show the beam should be stable 
to well above the SNS operating point, but a simple application of a 
Tigner / Chou handbook formula indicates otherwise. This will be pursued, and 
Holmes will add longitudinal simulations in his talk.

S. Henderson noted that the impedance from the extraction kickers and from 
the resistive wall is greater than that from the injection bump magnets, so 
effort should concertrate on the former. Recent analysis indicates that the 
closed orbit instability identified by S. Danilov should not be a problem,
as the max. injection kicker impedance amplitude is at too high
a frequency to be of a concern.

J. Galambos discussed the application programing infrastructure developement. 
A new approach is being taken with the lead of C. Allen and ORNL. 

D. Jeon discussed the matching study for the DTL/CCL, assuming mismatches 
into the DTL and quad errors. Comments included suggestions to use smaller 
quad errors (<< 20%)  and mismatch errors (< 30%), look for algorithms that 
converge fater than 100 iteration. This should greatly help the situation.