Introduction Main limitations (some of) acceptances & emittances space-charge

1. IS IT POSSIBLE TO INCREASE THE p INTENSITY FOR CNGS BY A FACTOR 2 OR 3 ?R. CAPPI / SL Seminar, 21.03.2002 • Introduction • Main limitations (some of) • acceptances & emittances • space-charge • double batch injection • bunch flattening • 5 turn Continuous Transfer • new 5t CT • List of various schemes • Conclusion

2. Introduction • The talk is a ‘simplified’ summary of the paper:CERN/PS 2001-041 (AE) or CERN/SL 2001-032 • speculations => studies & experiments • all results are PRELIMINARY and generally OPTIMISTIC • the talk will be mainly devoted to PSB-PS issues • I will not talk about collective effects ( except sp. ch.), longit. beam dynamics issues , transition crossing, etc.

3. Introduction: basic limitations • NB: The present scheme is “consistent” • i.e. LINAC, PSB, PS and SPS are all close to their limits, • i.e. there is not a single weak point • Linac2 • Close to its max Ip • PSB • Space charge ~limited • Ek,max limited (1.4GeV) • PS • Acceptance ~limited • Space charge ~limited • 5t Continous Transfer • …. • SPS • Acceptance limited • …. • Common: T & L collective effects, losses, transition, PRF , etc. recent results

4. Acceptance & emittance issues PS acceptance: Ax=60mm, Ay=20mm ex2< 22mm, ey2< 9mm LHC ~ 5 5 Ex2 Experiments Ax limit Ey2 Ay limit Courtesy of R.Steerenberg

5. PSB PS SPS Present scenario & associated problems L2 50 MeV Limit Nt = 3.3 ex< 22 ey< 9 1.4 GeV, h<0.9 DQ x,y~ 0.13 , 0.23 ex= 25 ey= 12 Nt = 3 14 GeV/c; 5t CT ; h=0.8 • NB: in all transparencies: • ex= 4sx2/bx in mm • intensities Nt are in 10^13 p • 3) h is the transfer efficiency • 4) yp is the p flux on target in 10^13p/s X Limit ex= 4.2/3 = 1.4 ey= 2.5 ex< 3 ey< 2 Nt = 4.8 G.Arduini filling time = 1.2s yp = 4.8/6 = 0.8 G = 1

6. Space charge (at low energy in the PS) Self field tune shift: In the PS, to be safe : If : T=1.4 GeV, ex = 22mm, ey = 9mmNt < 4.8 E13 p/p (Kb=8) to reach it WE NEED ADOUBLE BATCH INJECTION NB: the SPS filling time will increase by 1.2 s (or 0.6 s if PSB can pulse 2x faster* ) PS LIMIT *) M.Benedict et al. , undergoing study

7. PSB PS SPS Double batch injection into PS: forecast L2 50 MeV Limit Nt = 2 x 2.4 ex< 22 ey< 9 1.4 GeV; h=1 ex= 21 ey= 9.2 DQ x,y~ 0.21 ; 0.35 Nt = 4.8 => Intensity limit for a PS @ 1.4 GeV 14 GeV/c; old 5t CT;h=0.8 Limit X ex= 3.4/3 = 1.13 ey= 1.4 ex< 3 ey< 2 Nt = 7.7 yp = 7.7/7.2 = 1.07 G = 1.34 yp = 7.7/6.6 = 1.17 if PSB@.6s, G = 1.46

8. Recent results of high intensity double batch injection studies Experiments PS transformer Beam intensity ( E10 p/p) 1st batch 2nd batch Time (ms) Courtesy E. Metral

9. Comparing with LHC “ultimate beam” DQ = 0.20, 0.26 PS transformer Beam intensity ( E10 p/p) Time (ms) Courtesy G.Metral,E. Metral

10. Can we improve space charge limits? • Increase injection energy (e.g. with SPL) • Reduce Ip by ‘bunch flattening’ techniques: • (gain <1.5) time

11. A new bunch flattening technique (*) (*) C.Carli /CERN-PS-2001-073-AE and EPAC2002

12. Bunch flattening in PSB: recent results Final bunch Initial bunch Experiments DQ reduction of ~28% Courtesy C.Carli

13. 5 turn Continuous Transfer It is the way the PS uses to fill the SPS (at 14 GeV/c) CSPS = 11 x CPS PS PS SPS Present system: + it works - it is lossy (~20%) x’ 2 Qx = 6.25 3 1 5 x Extracted beam 4 . TT2 transfo 1 2 3 4 5 ES blade time, 2ms / div

14. Initial state Final state Simulation results Simulation results Proposal for a new 5t CT(*) The principle: • the beam is adiabatically captured into 4 islands of a 4th order resonance properly adjusted with sextupoles and octupoles, ES 2) then the beam is extracted similarly to the present scheme. (*) M.Giovannozzi, R.Cappi ; Phys. Rev. Lett., V.88, i.10

15. n 5t CT: pro / con + it should be less lossy (~5%) + the five beamlets will match the phase space topology better => less betatron mismatch at injection in the SPS=> lower transv. emittance beam to SPS => lower losses => higher intensity - it has to be tested experimentally

16. n5tCT: (x, x’ ) topology qx Courtesy M.Giovannozzi time ~ 30 ms

17. n5tCT: x-x’ measurement results Courtesy M.E.Angoletta, A-S.Muller, M.Martini,…)

18. MAD simulations Courtesy A-S.Muller

19. MAD simulations (suite) Courtesy A-S.Muller

20. PSB PS SPS Expected results from: double batch+ n5tCT L2 50 MeV Nt = 2 x 2.4 ex< 22 ey< 9 1.4 GeV, h=0.9 ex= 21 ey= 9.2 Nt = 4.8 14 GeV/c; new5t CT; h=0.9 ex= 3.4/5 = 0.68 ey= 1.4 ex< 3 ey< 2 RMKS: 10% improvement => h=0.9 =>lower transfer losses, better matching, etc. Nt = 8.6 filling time = 2.4s yp = 8.6/7.2 = 1.19 G = 1.49 yp = 8.6/6.6 = 1.30 if PSB@.6s G = 1.63

21. What about the SPS ? • Single bunch coll. effects: • 8.6E13ppp => 2 E10 p/b [LHC~10 E10; e-cloud > 4 E10 (5ns?)] • Transverse impedance strongly reduced since 2002 => ~OK • Beam loading: • 8.6E13ppp => 0.4 E13/ms [ LHC~0.5 E13p/ms]~OK • better if p=26GeV/c • Transv. & long. Feedbacks • HW modifications? 20=>100 MHz? • octupoles :YES (some e x,y b.u. accepted) ~OK ? • Transition: • now 5% losses, • better if p=26GeV/c • Etc. K.Cornelis, T.Linnecar, E.Schaposnikova,…

22. The various schemes

23. Conclusion • first studies show encouraging results not onlyfor CNGS but for LHC itself and for cleaning up the machines by improving reliability • a gain in p flux of ~1.5 seems feasible though difficult (cost ~0-2MCHF) • a gain of ~2 is maybe possible but will be more expensive(~50MCHF) • a gain of 3 will be VERY expensive ( ~300MCHF) and probably technically unrealistic • we need a.s.a.p. clear priorities to continueat efficient speed.