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Working groups status report on Feedbacks

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Working groups status report on Feedbacks

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  1. Working groups status report on Feedbacks A.Drago, K.Bertsche SuperB Meeting   26-30 January 2000 SLAC

  2. Main Topics • SuperB parameters • Subsystem main list • R & D • Conclusion

  3. Machine parameters • The SuperB machine parameters must be finalized before we can finalize the feedback systems, in particular: • Harmonic number to design b-b-b feedbacks • Bunch / beam current to dimension power and number of feedback systems: this also affects machine impedance (see Krasnyck’ talk) • Transverse / longitudinal damping time (same goal) • Beam vertical emittance to study the impact of feedback system

  4. Subsystem main list • B-b-b longitudinal feedback • B-b-b transverse feedback • Dither feedback • Fast IP feedback • Low level RF • Longitudinal Bunch Position Control • 1D or 2D bunch-by-bunch diagnostics

  5. R & D • Bunch by bunch longitudinal feedback - the present system is based on very old DSP (digital signal processor) that are completely obsolete - a new version (the so called G-Proto or iGp) is based on a FPGA (V-II) that is ~10 years old, it will become obsolete in 2/3 year -a new design is necessary based on last version FPGA - the digital processing unit design is in progress, the system will work at 12/16 bits to have a better dynamic range respect to the old 8 bit systems - the analog front end/back end needs to be re-designed as well for compatibility with digital and due to the obsolescence of some parts - kicker (cavity) and amplifiers are probably ok, but it should be evaluated for working with bunch pattern by 1 (i.e. ~2ns pulse)

  6. R & D • Bunch by bunch transverse feedback - for best use of resources, the digital processing unit should use the same design as the longitudinal unit - attention should be given to the kicker design to maintain low ring impedance in case of multiple feedback installation - kicker response must be adapt for 2ns pulse (bunch space by 1)

  7. R & D • Dither feedback • Dither in x, y, and (probably) y’, similar to existing system • Upgrades to existing system: • Dither at 1-3 kHz • More efficient coil designs to allow lower currents and smaller drivers • Fast corrections (above ~1 Hz) through dither system • Slow corrections (below ~1 Hz) through standard correctors

  8. R & D • Fast IP feedback - it can be implemented in parallel to the dither feedback (in particular on the vertical plane) - it is independent from the transverse feedback but it uses identical hardware with different firmware/software - it can be used bunch by bunch - sensitivity and signal/noise are open questions  need tests and simulations - it is not clear if the kicker should be identical the transverse kicker or different

  9. R & D • Low level RF • necessary • opinion of the experts (Dan Van Winkle / Claudio Rivetta) is that it will soon be obsolete and must be redone using newer FPGAs • needs a Matlab simulator that should be upgraded for the SuperB parameters (C.Rivetta) • new design should be done by experts: e.g. the J.Fox team at SLAC or outsourced to Dimtel (D.Teytelman)

  10. R & D • Longitudinal Bunch Position Control - same as LLRF - Claudio Rivetta has good know how and a good simulator

  11. R & D • 1D or 2D bunch-by-bunch diagnostics • Diagnostics in 1D or 2D, bunch-by-bunch and turn-by-turn, seems necessary for colliding two beams with so small vertical emittance and sigma • Without valid real time tools, it could be impossible to evaluate the wasting of luminosity along the bunch train

  12. Conclusions • We have considered a list of subsystem with similar technological characteristics or with similar goals • All systems need at least some redesign • Unify the technological choices can help to request less design manpower and to simplify the system management