Accelerator Physics Meeting 12/15/00

Present: J. Wei, S.H. Kim, M. Doleans, Weishi Wan,
D.O Jeon, Sarah Cousineau, J. Galambos,Paul Chu, Eugene Tanke,
Bob Gluckstern, Alexei Fedotov, Slava Danilov

Jie welcomed Eugene Tanke to the group. He noted that Ingo Hoffmann will be 
visiting from April to July 2001 (at BNL and ORNL). 

The ASAC meeting in Feb. requires imediate work, as well as input
to the project office for upcoming decisions on budget cutting measures.
In particular decisions need to be made by Jan. 8, 2001 on the need 
for sextupoles, HEBT cavities, ground breaks, and HEBT/RTBT
line BPMs/trim quads. The path to providing input on these issuse was 
discussed. Most important is the sextupole and corrector issuses. In order
to get input by the above dates, a somewhat simplified approach will be
taken that does not necessarily include all effects simultaneously.

First, from an assumed linac input distribution (with some 
residual beam in gap) a painted ring emittance will be constructed.
Then for a set of different linac energies (J Galambos will provide) 
corresponding to 12, 15, 18 and 21 high beta cryo-modules) the following
effects will be analyzed.
The space charge tune shift effect (and tune spread) will be analyzed
by Jeff and Weshi. The chromaticity shift (from dp/p) will be independently
looked at. The effect of fring field tune shift is expected to 
be small compared to the other effects looked at, so it will not be 
included. The FOM will be beam loss. Anything on a 4th order
resonance will be assumed to be lost. Slava will look at the dp/p 
requirement for stability. In order to calculate the accetable beam 
intensity (hence SNS power) for a given energy a 10 kW limit
of power on the primary collimator will be taken (200 pi-mm-mrad).

The EMQ study will be undertaken by E. Tanke using trace-3D. The object will
be to 1st determine the lieklyhood of detecting a beam envelope oscillation
from some injection mismatch, given the SNS proposed wire-scanner locations
and expected resolutions. Then, will the proposed DTL EMQ trim quads be
able to affect the envelope oscillations.