1. Feedback for CESR TA Michael Billing May 17, 2007

2. Stability Measurements from May 1999 Damping Measurements - assumes coherent damping rate of where Single Positron Bunch Chromatic and Radiation Damping –Determined from coherent damping rates vs. current & chromaticity –   = H: 68 sec -1 V: 53 sec -1 –  /  I | Z = H: 5.8x10 -2 sec -1 mA -1 V: 8.3x10 -2 sec -1 mA -1

3. Stability Measurements from May 1999 Instability Thresholds vs Bunch Spacing –Computed Instability Growth Rates Relative H & V Instability Growth Rates –Comparison of H & V Instability Thresholds vs Chromaticity –Measured for 8 ns and 10 ns spaced bunches –Conclusion: H & V Instability Growth Rates within a factor of 2 of each other Conclude: Need ≥15 sec -1 mA -1 damping from Feedback in both transverse planes - longitudinal: no info (5/99)

4. Transverse Feedback Topological Block Diagram –BPM –Position Monitor Signal to Pulse Electronics –Cross Tunnel Wideband Coax Cable –Power Amplifier –Stripline Kicker BPM => pulse Amp Kicker

5. Installed H & V Transverse Feedback Electrical Block Diagram –Presently omits DC suppression circuit (use centered beam) –Relay switches to be added soon

6. Tests of 4 ns Transverse Feedback Positron Feedback –Timed & successfully tested H & V  FB ~ 90 sec -1 mA -1 –Stopped after 21 (1.4 mA) bunches –See onset of longitudinal motion at 18 mA total current (amplitude is limited) --> Growth rate of ~ 2 sec -1 mA -1 Electron Feedback –Timed in & successfully tested H & V with two 4 ns spaced bunches (stopped by CESR hardware failure) Remaining Work for Transverse Feedback –Finish electron test with long train –Formalize the switchover from e+ to e- H Ampl (5 dB /div) Time (1.25 ms /div) 32 mA total excitation damping