1. Vladimir Litvinenko, APEX Workshop 11/02/20006 IBS suppression lattice Mei Bai, Joanne Beebe-Wang, Peter Cameron, Roger Connolly, Angelika Drees, Alexei Fedotov, Wolfram Fischer, George Ganetis, Vladimir Litvinenko, Nikolay Malitsky, Aljosa Marusic, Christoph Montag, George Parzen, Fulvia Pilat, Vadim Ptitsyn, Thomas Roser,Todd Satogata, Steve Tepikian, Dejan Trbojevic, Nick Tsoupas, Jie Wei

2. Vladimir Litvinenko, APEX Workshop 11/02/20006 Content What is IBS suppression lattice? What are potential gains from IBS suppression lattice? What did we tested? What should we test? Conclusions

3. Vladimir Litvinenko, APEX Workshop 11/02/20006 Motivation Increase the Au-x Luminosity Life-time Reduces Back-ground Simplify requirements on Electron Cooling

4. Vladimir Litvinenko, APEX Workshop 11/02/20006 Transverse IBS in RHIC The main contribution to the transverse IBS in RHIC come from the arcs, most of which comprised of FODO cells

5. Vladimir Litvinenko, APEX Workshop 11/02/20006 Relative transverse IBS rate in RHIC Present operating point QxQx QyQy NOTE:  Q x.y are tune advances per one FODO cell

6. Vladimir Litvinenko, APEX Workshop 11/02/20006 Reduction of the IBS rate, i.e. increase of the luminosity lifetime  Q x /cell IBS(0.22)/ IBS(  Q x ) Present operating point NOTE:  Q x are tune advances per FODO cell  Q y = (0.9 or 1 or 1.1)  Q y 90 o 108 o 72 o 126 o 144 o

7. Vladimir Litvinenko, APEX Workshop 11/02/20006 Transverse IBS in RHIC for test lattice

8. Vladimir Litvinenko, APEX Workshop 11/02/20006 Test lattice for IBS suppression S.Tepikian

9. Vladimir Litvinenko, APEX Workshop 11/02/20006 S. Tepikian

10. Vladimir Litvinenko, APEX Workshop 11/02/20006 Transverse IBS in RHIC for test lattice A.Fedotov

11. Vladimir Litvinenko, APEX Workshop 11/02/20006 S. Tepikian

12. Vladimir Litvinenko, APEX Workshop 11/02/20006 Cu101 Ramp Editor Settings T. Satogata

13. Vladimir Litvinenko, APEX Workshop 11/02/20006 Cu101 Beam Experiment, Ramping Vladimir, Steve, Al, Vadim, Nikolay, Mei, NickL, Roger, Dejan, Rob, … T. Satogata

14. Vladimir Litvinenko, APEX Workshop 11/02/20006 Cu101 Beam Study Ramp Items  Circulated beam easily in both rings, injection retuned  Injection emittance is beautiful (6-7 mm mrad), optics okay  Four ramps, using only blue ring (yellow q89 PS not swapped)  Two ramps with Cu101, slow factors 2 and 3, still excursions and quench protection trips on q6 power supplies  Two ramps with Cu102, to lower energy (  =91.4), slow factor 1  Ramp tuning is mainly orbits/tunes, though coupling is an issue  Tunes/chroms in Cu101 now match well with model at injection  Chroms within 2-3 units, tunes within 0.03-0.04  Orbit/coupling corrected at injection, propagation up ramp not good  Dispersions re-measured in both rings at injection, looks okay  Transition never really explored, timing was always wrong and should be dead-reckoned for next study T. Satogata

15. Vladimir Litvinenko, APEX Workshop 11/02/20006 S. Tepikian Went to 31 GeV test

16. Vladimir Litvinenko, APEX Workshop 11/02/20006 S. Tepikian

17. Vladimir Litvinenko, APEX Workshop 11/02/20006 S. Tepikian

18. Vladimir Litvinenko, APEX Workshop 11/02/20006

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20. Vladimir Litvinenko, APEX Workshop 11/02/20006 S. Tepikian 31 GeV test

21. Vladimir Litvinenko, APEX Workshop 11/02/20006 S. Tepikian er

22. Vladimir Litvinenko, APEX Workshop 11/02/20006 Hardware Limitations Power supplies, leads and quenching Current distribution limitations - H & V strings, the tree of shunting PS… Sextupole strength Growth of  t and strength of  t quads Matching with desirable  * - Not needed for the test Dynamic aperture Effects on coupling compensations scheme, diagnostics using specific tune advances, etc….

23. Vladimir Litvinenko, APEX Workshop 11/02/20006 Latest simulations IBS calculation based on exact Martini’s model for dedicated experiment on IBS suppression (RHIC run-7): Au ions, 100 GeV/n e x =15 p mm mrad (95% normalized) e y =10 p mm mrad (95% normalized) RF: 300kV, h=360 to avoid loss from the bucket Several bunch intensities A.Fedotov

24. Vladimir Litvinenko, APEX Workshop 11/02/20006 Simulations: Bunch with intensity N=1e9, red – standard run-7 lattice; blue – 92 deg. phase advance lattice with the same RF voltage; green – 92 deg. lattice with voltage adjusted to have initial bunch length as for run-7 lattice. A.Fedotov

25. Vladimir Litvinenko, APEX Workshop 11/02/20006 Suggestion for the experiment 1.Due to possible fluctuation in IPM measurements, for convincing comparison of various lattices recording of emittance growth over the period of 2 hours or more is desired. 2.Experiment conditions for IBS suppressed lattice should be the same as for typical dedicated IBS experiment: 6 bunches, two for each of 3 different intensities. 3.Higher intensities per bunch are preferred. A.Fedotov

26. Vladimir Litvinenko, APEX Workshop 11/02/20006 Conclusions Already developed lattice (92 o ) promises to reduce transverse IBS by 1/3rd Good injection and reasonable ramp to 31 GeV (cross the  t ) had been tested IBS tests at 31 GeV were indecisive and confusing Examine possibility of further increase in the phase advance with present hardware Two hours measurements: both the base-line and IBS suppression lattice are desirable Requires tests of power supplies before the Run 7 Using both the yellow and the blue is very desirable

27. Vladimir Litvinenko, APEX Workshop 11/02/20006 Go over the IBS