Date May 18, 2000
Attendees M. Doleans,  S. Danilov, J. Galambos, J. Holmes, D. Jeon, S. Kim,  
J. Wei
 
J. Wei reviewed the proposed accelerator physics staffing plan. The staffing  
level in 2006 is proposed to be 17 + 2 post-docs + 1 secretary. This includes 
6 ring team staff, 6 linac/FE team staff, 2.5 application team staff, and 2.5 
software team staff. 

J. Galambos presented initial results from a corrector / BPM study for the 
DTL. Using between 8 and 5 correctors per tank, 2 BPMs per tank, and the 
nominal linac error distributions, most of the error induced beam 
displacement and aperture filling can be corrected. Corrector strengths 
less than ~ 1000 gauss-cm are required. Sensitivities to the number of 
correctors and their placement are underway. 

Jeff Holmes discussed work simulating the PSR beam. He is looking at the 
impact of the longitudinal bunch factor evolution during injection and its 
effect on pushing the tune towards the nu_y=2 resonance. A spectral analysis 
of the beam moment oscillations indicate at 2nd order beam oscillation at 
nu_y = 4.

Jeff Holmes and S. Danilov are working on the longitudinal impedance, trying 
to benchmark the model in ORBIT with an analytic case and with J. McLaughlin. 

Slava Daniolov is concerned about instabilities in the SNS ring, in 
particular from the extraction kicker and from the RF cavity impedances. 
He is modeling the extraction kicker with MAFIA. The low frequency results 
are similar to measurements from Lambertson, and high frequency results are 
close to measurements from J. G. Wang. He feels that these results are 
probably OK within a factor of 2. The electron catcher design is still a 
problem in that it is difficult to find the location catcher which works for 
all conditions expected in the SNS (i.e. different injection energies). 
Electron incident energies range from a few eV (secondary) to 500 KeV 
(from the stripped injected H-) and the catcher is expected to be hot. 

D. Jeon is studying the HOM theory from JLab papers.  Regarding the 
comparison of linac models, results from Ji Qiang of LANL indicate that the 
Scheff model produces different results from a detailed 3-D space charge 
model for bunch aspect ratios > 3, due to differences in the treatment of 
the radial variations. There is a need to compare parmila and the more 
detailed 3-D model.

Sang ho Kim and Marc Doleans have started HOM with Superfish.