1. BIW 2006 Simultaneous Tune and Coupling Feedback during RHIC Run 6 Peter Cameron

2. BIW 2006

3. Acknowledgements Tom Shea – the foundation and foresight Mike Harrison, Steve Peggs, Alex Ratti –US LHC Accelerator Research Program RHIC HF Instrumentation –Earlier efforts BNL C-AD Instrumentation – Tom Russo et al –The present effort

4. BIW 2006 Outline System Architecture Direct Diode Detection (3D) AFE Eigenmodes, set and measured tunes,… Coupling and de-coupling –essential for tune feedback Ramping with and w/o feedbacks 3D AFE ‘Beam Noise’ Susceptibility Plans

5. BIW 2006

7. 10nm

8. BIW 2006 eigenmodes rotated wrt horizontal and vertical planes due to coupling. special case general case

9. BIW 2006 Set and Measured Tunes Measured tunes –The ‘eigenvalues’ – physical observables –Rotated from H and V by coupling Set tunes –What tune would be in the absence of coupling –dQ min – forbidden zone complicates tune control without feedback breaks feedback –can be calculated with knowledge of coupling

10. BIW 2006 Set and Measured Tunes set measured

11. BIW 2006 tune feedback would break here

12. BIW 2006 Manual Decoupling Skew chrom 0 Chrom measurement

13. BIW 2006 dQ min <.001

14. BIW 2006

15. Coupling Echoes ½ synchrotron period 1 sec Coupling coefficient ‘C’ 0.02

16. BIW 2006 Outline System Architecture Direct Diode Detection (3D) AFE Eigenmodes, set and measured tunes,… Coupling and de-coupling –essential for tune feedback Ramping with and w/o feedbacks 3D AFE ‘Beam Noise’ Susceptibility Plans

17. BIW 2006 First Ramp with Feedbacks

18. BIW 2006 First Ramp with Feedbacks 2

19. BIW 2006 Last Blue Ramp with Feedbacks

20. BIW 2006 Next Ramp with Feedbacks Off

21. BIW 2006 Beam Noise Steve Peggs – “declare Victory” Peter Cameron – “Mission Accomplished” One messy little detail –3D AFE sensitivity to ‘beam noise’ –No free lunch

22. BIW 2006 3D AFE ‘beam noise’ Beautiful when looking at amplitude –Very sensitive ~10nm –Resistant to dynamic range problems (bunch length, beam offset,…) But, when you put it in a phase loop…. Possible sources –Beam loss –High frequencies - longitudinal ‘hot spots’ –Low frequencies quadrupole cryostat vibrations mains harmonics –Instabilities (weak – not noticed by anything except 3D AFE) –Long range beam-beam

23. BIW 2006 Immediate plans Further investigation of ‘beam noise’, and how to cope with this Chromaticity measurement and feedback Movement of the system into the CERN architecture – DAB board

24. BIW 2006Conclusions World’s first implementation of simultaneous tune and coupling feedback is successful The door remains open for simultaneous tune, coupling and chromaticity feedback at LHC

25. BIW 2006 Back-up slides

26. BIW 2006 3D on the Ramp - 1 Jan 05 dominant spacing is 180Hz 60Hz onset 60Hz end IPM every 100 turns (780 Hz)

27. BIW 2006 Transverse instability Not fixed by chrom Frequently present at a level not detectable by anything other than BBQ Upper half of sideband

28. BIW 2006 Summary of Chromaticity tt tt vert horiz +5 -5 dp/p of +/-10 -4 gives ~+/-100  radial modulation (RHIC&LHC) -5 +5 Q' ramp 6380 ramp 6382 ramp 6381 in RHIC modulation is at 1Hz chrom - good results under sequencer control