Summary Notes of the SSWG meeting on the 29/10/2002

Present: G. Arduini, T. Bohl, H. Burkhardt (secretary), K. Cornelis 
(chairman), B. Dehning, W.Hofle, L. Jensen, T. Linnecar, F. Roncarolo,
J. Tuckmantel.

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Agenda :

Topic : transverse emittance conservation.

1) Studies on instabilities and tunes,   G. Arduini

2) Studies with the damper W. Hofle  -  postponed

3) space charge tune shift,   H. Burkhardt

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1) G.A. showed observations in the transverse plane, see transparencies
attached. The working point 0.185/0.13 is confirmed. High chromaticity 
of the order of xi = 0.6 - 0.7 is used for horizontal stability at the 
beginning of the ramp. It was observed, that coupling can also help.
There is a strong energy dependence. Growth at higher energies is much 
slower, still a damper is needed at 450 GeV.
Nominal LHC parameters can be obtained for 3 batches and marginally 
with the fourth batch.
Due to a bug in the low level software of the rotational wire scanners, 
emittance measurements before mid october were too high by about 30 %.
Beam phase space reconstruction observations were shown and may give 
additional input for the understanding of the electron cloud 
instability.

2) Studies with the damper -- postponed to the next meeting in two 
weeks.

3) H.B. showed preliminary results on space charge for high intensity 
(1.2e11) single bunches at 14 GeV/c in the SPS (see transparency).
The space charge tune shift (spreads) calculated from the bunch 
parameters reached about -0.2 vertically and -0.16 horizontally.
Lifetimes were very poor for low (< 0.1) and high (> 0.45) tunes, but 
reasonable for tunes around 0.25.


The next meeting is foreseen in two weeks with observations in the 
longitudinal coordinate as main topic.