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Summary

Preliminary results: Beam-Beam Transfer Function for Luminosity Optimization P. Cameron, A. Drees, A. Dellapenna,…. Summary. The approach at CESR Radiation damping means they can kick hard Look off resonance The approach at RHIC Excitation power is limited by emittance growth

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Summary

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  1. Preliminary results:Beam-Beam Transfer Function for Luminosity Optimization P. Cameron, A. Drees, A. Dellapenna,… apex bbtf 11Apr07

  2. Summary • The approach at CESR • Radiation damping means they can kick hard • Look off resonance • The approach at RHIC • Excitation power is limited by emittance growth • Excite ‘on resonance’ to enhance the coupling • Results • We observed anti-correlation between ZDC’s and BBTF! • This is not understood, no obvious cause • Higher excitation levels caused emittance growth • No plan to further pursue on-resonance excitation • Future request • 2 hours in 2 weeks to study off-resonance excitation apex bbtf 11Apr07

  3. CESR system apex bbtf 11Apr07

  4. The APEX procedure as originally conceived • Take swept BBTF to find zero phase • Lock BBQ thru the continuous BBTF • Do vernier scan • Compare amplitude of BBTF and vernier scan results • This can be done parasitically early in the run, to get preliminary results? apex bbtf 11Apr07

  5. The APEX procedure as done • Concern with effects of phase shifts due to beam-beam corrupting the ‘tune-tracking’ approach • Solution was • Excite beam in one ring with white noise – more robust, does not require locking BBQ to beam • Do vernier scan • Record data with BTM DAQ for offline analysis • Initial offline analysis is spectral power within a specified tune window apex bbtf 11Apr07

  6. Beam-Beam Transfer Function excite here measure here Beam Transfer Function measure here excite here yellow beam blue beam apex bbtf 11Apr07

  7. Blue beam response to white noise excitation in yellow (both planes), as seen by the ‘back-up’ DAQ (turned out to be un-needed) H V apex bbtf 11Apr07

  8. ZDC signals during the first two position scans apex bbtf 11Apr07

  9. BPM signals during the first position scan apex bbtf 11Apr07

  10. 3D AFE signals during the first position scan apex bbtf 11Apr07

  11. apex bbtf 11Apr07

  12. BTF – yellow excitation BBTF – blue response BBTF – blue response Integral of 3D AFE FFT in the tune window from .215 to .24 during the first position scan apex bbtf 11Apr07

  13. BBTF – blue vert response BBTF – blue horiz response apex bbtf 11Apr07

  14. The vernier scan app for the first position scan apex bbtf 11Apr07

  15. forgot to turn kicker off 1st scan 2nd scan apex bbtf 11Apr07

  16. IPM 1st scan 2nd scan Schottky apex bbtf 11Apr07

  17. 1st scan 2nd scan apex bbtf 11Apr07

  18. apex bbtf 11Apr07

  19. apex bbtf 11Apr07

  20. Summary • The approach at CESR • Radiation damping means they can kick hard • Look off resonance • The approach at RHIC • Excitation power is limited by emittance growth • Excite ‘on resonance’ to enhance the coupling • Results • We observed anti-correlation between ZDC’s and BBTF! • This is not understood, no obvious cause • Higher excitation levels caused emittance growth • No plan to further pursue on-resonance excitation • Future request • 2 hours in 2 weeks to study off-resonance excitation apex bbtf 11Apr07

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