Accelerator Physics Meeting 12/8/00

Present: J. Wei, S.H. Kim, M. Doleans, Weishi Wan,
D.O Jeon, Sarah Cousineau, J. Galambos,Paul Chu

Jie Wei noted that Norbert Holtkamp is coming to SNS in Feb. 01,
and will be replacing Bob Kustom. He also discussed the group staffing
and noted that the position of the senior linac leader is still open.
The participation of the partner labs during commisioning 
is being discussed. There are cuts in their previously planned 
participation levels. He discussed the status of the 
ongoing DOE review. There are hard questions being asked on th project
as well as the AP group level. The questions are technical as well
as budget. A theme of the questions centers on the importance 
of the beam energy and the impact of lowering it.

J. Galambos discuused the new server (NT and Linux) structure. The top
level is reduced to 4 directories. Personal work should not
be kept here, but whe a task is finished, the technical aspects of 
the work (input, output files etc.) are encourgaed to be put there. 

The PAC 01 paper topics were discussed. Each person proposed a topic
to write an absract on. (Galambos, Chu - application programing, Wei - ring
injection, Kim, Doleans - HOM analysis, 
Jeon - ring space charge comparison, Cousineau - BIG kicker.)

Jie Wei noted that there was a propoasal to put solenoid windings on
the ring vaccum pipe to inhibit the electrom motion (and hence the 
e-p instability). The technical practicalities of this proposalare being
investigated.

M. Doleans showed the progress in the off-axis, off-angle particle motion
in the cavity fields. There is a negligible impact for particles starting
near the cavity axis. The impact is larger (but still small) for particles
starting ~ 5 mm off axis. The impact on emittance blowup is being 
investigated.




reviewed the status of the upcoming DOE review, and noted 
the need to maintain calm despite apparent turmoil. There are large
cuts in line item and operation budgets (e.g. ring crane, the HEBT
cavities). He noted the need to keep a consistent set of parameters.
Jie reviewed his trip to Sacalay, noting that there is a movement to 
initiate a design of a multi-purpose facility there
(independent of ESS). They are considering starting
from the SNS ring design as opposed to the ESS ring. They are strong 
on the linac, but weak on the ring design. They want to creat a CDR by 
03. There was an e-p R&D review, despite its budget being cut. LBNL
is doing 3-D electrostatic modeling of the electrons,
PPPL doing Vlasov modeling of the ions (minus ring physics). The 
proposal is to continue the LBNL work and get input from previous 
SNS work. 

John Galambos discussed the ICANS workshop and his KEK-JAERI trip.
At ICANS there was strong accelerator representation from the 
JKJ team. They are aggressivly pursuing a spallation source of the same
power level as the SNS, and with a similar schedule. They are strong
on he linac (well along R&D at both KEK and JAERI), but lag behind
SNS in the ring effort. The 3 GeV ring design is being done at JAERI.

Dong O discussed the linac code benchmarking meeting at LANL. L. Young
presented differences in results from parmila and parmela, a baseline
device to be used in comparisons was discussd and the idea
of inputing differnces in the offaxis field (calculated externally).

Paul and Sarah dicussed the latest space charge results at IUCF. The
new chopper was installed resulting in clean injection and storing of
muti-turn injection. Results were shown indicating clean looking
profiles.

Slava disussed the excited state H_o state work. There is an uncertainty
in the state lifetimes, resulting in a  small window of acceptable field 
level for the injection dipole.


Sang ho discussed Q_ext calculations for the fundamental coupler. 6 pass
bands are done. The process is more difficult for the HOM coupler. Field
maps have been sent to JLab. Marc is looking at the cavity misalignement
impacts (e.g. from tilts of cavities). The HOM coupler positioning work
is continuing. A joint ORNL / Jb tech note is being prepared. 

Sasha discussed a MEBT commisioning algorithm that will adjust quad 
strengths to match observed profiles with predicted profiles. A MathCad
program is running, and differnet minimization schemes explored for
robustness.

Weishi Wan discussed the global coordinate status. Some additional
information has been given to the conventional facility people.He noted
that FNAL does not see jitter in their linac.