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Prototyping in the SPS using pickups equipped with LHC electronics
Meeting held on Friday 6-07-2001 - reported by Mike Lamont
Present : A. Butterworth, M. Lamont, Lars Jensen, Jean-Jacques Gras,
Rhodri Jones, Hermann Schmickler, Joerg Wenninger, Thijs Wijnands, Pedro Ribeiro
Agenda :
Prototyping in the SPS using pickups equipped with LHC electronics
Minutes :
Prototyping global orbit control on the SPS machine network
Thijs presented the results of his and Joerg's investigations: "Prototyping
global orbit control on the SPS machine network". Slides here.
Among the points covered in his presentation were:
- Origins of orbit distortions in the LHC
- Basics of orbit correction and advantages of SVD
- Speed of SVD correction on various platforms (between 20 & 83 ms, 500
BPMs, 300 correctors, number of eigenvalues not quoted). Impact of choice
of OS depended on time scale required of correction.
- Choice of Protocol: UDP or TCP. Choice should be transparent for BI.
- Synchronization of acquisition & actuation - questions...
- A brief look at the dynamics of closed loop control
Results to be published in an SL note soon.
I also note:
- 2 to 3 ms for the network (native ATM),
- Effect of random delay (within limits) should be included in the dynamics
model.
- Effects of different time constants in power converters (warm & cold),
(different loading of power converters involved) should be considered.
- Optics errors originating outside a closed bump do not effect the optics
of the bump.
Installation of additional pickups in SPS
Rhodri & Joerg reporting:
- 6 possible areas near IR5, between 514 and 522. Covers at least one betatron
oscillation, plus varying degrees of dispersion.
- Good for Gianluigi's request for 2 pickups with which to reconstruct phase
space.
- Minimum number of pickups required: minimum 4, maximum 6, no more than 6.
Lots of corrector power. Possibly only one plane equipped.
- Final confirmation with Claude Fischer & Gianluigi required.
- BPM design care of JJ Papis - should only take a few hours work
- Cables to front-end electronics placed outside tunnel (access required).
- Cards to be ordered from Triumph (2nd prototype)
Meet in 2 weeks to finalise proposal, for presentation to SLTC mid-August.