Abstracts Brochure - CERN

THPCH — Poster Session 29-Jun-06 16:00 - 18:00
new system and some advantages of multiple PID loops in the eigenvector space versus a single PID loop working
on the raw orbit error.
Design and Testing of Gproto Bunch-by-bunch Signal Processor
A prototype programmable bunch-by-bunch
signal acquisition and processing channel
with multiple applications in storage rings
has been developed at SLAC. The processing
channel supports up to 5120 bunches with
D. Teytelman, R. Akre, J.D. Fox, A. Krasnykh, C.H. Rivetta, D. Van
Winkle (SLAC) A. Drago (INFN/LNF) J.W. Flanagan, T. Naito, M.
Tobiyama (KEK)
bunch spacings as close as 1.9 ns. The prototype has been tested and operated in five storage rings: SPEAR-3, DAFNE,
PEP-II, KEKB, and ATF damping ring. The testing included such applications as transverse and longitudinal coupledbunch
instability control, bunch-by-bunch luminosity monitoring, and injection diagnostic. In this contribution the
prototype design will be described and its operation will be illustrated with the data measured at the abovementioned
accelerators.
Design and Simulation of the ILC Intra-train Orbit and Luminosity Feedback Systems
To maintain luminosity to within a few percent
of the design at the International Linear G.R. White, G.R. White (JAI) D. Schulte (CERN) N.J. Walker (DESY)
Collider (ILC), beam stability at the IP needs
to be maintained at the sub-nanometre level. To achieve the beam stability required in the presence of ground motion,
multiple feedback systems are required. The baseline design calls for a 5-Hz system to control the orbit in the Linac
and Beam Delivery System (BDS) and an intra-train system to address high-frequency ground motion and mechanical
disturbances which cause orbit distortions at the IP between pulses enough to completely destroy the luminosity.
Details of the slower feedback systems have been addressed elsewhere*. The detailed design and simulation of the
intra-train feedback systems are described here. This system controls the vertical position and angle at the IP such that
luminosity is maximised. The system brings the beams into collision based on BPM-derived information from the
initial bunches of the train. It then tunes the IP collision parameters (both position and angle) based on a fast (bunchby-bunch)
luminosity signal from the BeamCal. The system is implemented in fast digital FPGA logic, designed using
Matlab’s Simulink.
*A. Seryi et al. "Issues of Stability and Ground Motion in ILC", Nanobeam 2005.**G. White et al. "Multi-Bunch
Simulations of the ILC for Luminosity Performance Studies", PAC2005.
Summary of Coupling, Tune, and Chromaticity Feedback Results during RHIC Run 6, and
Possible Implications for LHC Commissioning
Efforts to implement tune feedback during
the acceleration ramp in RHIC have been
hampered by the effect of large betatron coupling,
as well as by the large dynamic range
P. Cameron, A. Della Penna, L.T. Hoff, Y. Luo, A. Marusic, V. Ptitsyn,
C. Schultheiss (BNL) M. Gasior, O.R. Jones (CERN)
required by transition crossing with ion beams. Both problems have been addressed, the first by implementation
of continuous measurement of coupling using the phase-locked tune meter, and the second by the development of
the direct diode detection analog front end. Performance with these improvements will be evaluated during the
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