1. News from eRHIC and advanced cooling schemes for high energy hadron beams Vladimir N. Litvinenko for BNL’S eRHIC team and CAD’s AP group Inputs on Physics from BNL EIC task force, E.-C.Aschenauer, T.Ulrich A.Cadwell, A.Deshpande, R.Ent, W.Gurin, T.Horn, H.Kowalsky, M.Lamont, T.W.Ludlam, R.Milner, B.Surrow, S.Vigdor, R.Venugopalan, W.Vogelsang Inputs on LHC and LHeC from F.Zimmerman, R.Thomas, O.Brüning Brookhaven National Laboratory, Upton, NY, USA, Stony Brook University, Stony Brook, NY, USA Center for Accelerator Science and Education V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

2. Content News from eRHIC Updates on coherent e-cooling How it can be applied for LHC/LHeC Conclusions 2 V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

3. eRHIC Scope -QCD Factory e-e- e+e+ p Unpolarized and polarized leptons 4-20 (30) GeV Polarized light ions (He 3 ) 215 GeV/u Light ions (d,Si,Cu) Heavy ions (Au,U) 50-100 (130) GeV/u Polarized protons 25  50-250 (325) GeV Electron accelerator RHIC 70% beam polarization goal Positrons at low intensities Center mass energy range: 15-200 GeV e-e- 3 V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

4. 2007 Choosing the focus: ERL or ring for electrons? Two main design options for eRHIC: –Ring-ring: –Linac-ring: RHIC Electron storage ring RHIC Electron linear accelerator Natural staging strategy ✔ L x 10 4 V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

5. MeRHIC is a single IP coolider 4 GeV e x 250 GeV p – 100 GeV/u Au 2 x 60 m SRF linac 3 passes, 1.3 GeV/pass STAR PHENIX 3 pass 4 GeV ERL Polarized e-gun Beam dump MeRHIC detector 5 V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

6. 4 GeV e x 250 GeV p or 100 GeV/u Au 120m SRF linac 3 passes, 1.3 GeV/pass 6 STAR PHENIX 3 pass 4 GeV ERL Polarized e-gun Beam dump M/eRHIC detector MeRHIC V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

7. Integrated low-X IR design, β *=25 to50 cm p, Au e Solenoid, 4 T 1T, 3m dipole 1T, 3m dipole First machine elements 20 m from IP 40 m to detect particles scattered at small angles To provide effective SR protection: -soft bend (~0.05T) is used for final bending of electron beam © J.Bebee-Wang 40 m Soft dipole Soft dipole MeRHIC IR L=3x10 33 © E. Aschenauer V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

8. eSTAR ePHENIX Staging all-in tunnel eRHIC: energy of electron beam is increasing from 5 GeV to 30 GeV by building-up the linacs 2 SRF linac 1 -> 5 GeV per pass 4 (6) passes 4 to 6 vertically separated recirculating passes. # of passes will be chosen to optimize eRHIC cost Coherent e-cooler 5 mm 20 GeV e-beam 16 GeV e-beam 12 GeV e-beam 8 GeV e-beam Common vacuum chamber Gap 5 mm total 0.3 T for 30 GeV eRHIC detector injector RHIC: 325 GeV p or 130 GeV/u Au The most cost effective design V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

9. eRHIC eRHIC loop magnets: LDRD project Small gap provides for low current, low power consumption magnets -> low cost eRHIC Dipole prototype is under tests Quad and vacuum chamber are in advanced stage 25 cm Gap 5 mm total 0.3 T for 30 GeV 5 mm 20 GeV e-beam 16 GeV e-beam 12 GeV e-beam 8 GeV e-beam Common vacuum chamber ©, G. Mahler, W. Meng, A. Jain, P. He, Y.Hao V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

10. ARC 1.27 m beam high 30 GeV e + ring 30 GeV ERL 6 passes HE ERL passes LE ERL passes 30 GeV 25 GeV 20 GeV 15 GeV 10 GeV 5 GeV V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

11. Linac SS 1.27 m beam high e + ring 200 m ERL Linac V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

12. eRHIC Linac Design 703.75 MHz 1.6 m long Drift 1.5 m long to Dump E max Total linac length depend on energy All cold: no warm-to-cold transition Based on BNL SRF cavity with fully suppressed HOMs Critical for high current multi-pass ERL ©I. Ben Zvi ©George Mahler Injection Energy of electron beam is increased in stages by increasing the length of the linacs V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

13. TBBU stability (©E. Pozdeyev) Excitation process of transverse HOM eRHIC HOMs based on R. Calaga’s simulations and on recent measurements 70 dipole HOM’s to 2.7 GHz in each cavity Polarization either 0 or 90° 6 different random seeds HOM Frequency spread 0-0.001 F (GHz)R/Q (Ω)Q(R/Q)Q 0.889257.26003.4e4 0.891657.27504.3e4 1.77733.470842.4e4 1.77743.471672.4e4 1.78271.798991.7e4 1.78281.789671.5e4 1.78475.142002.1e4 1.78485.142002.1e4 Threshold significantly exceeds the beam current, especially for the scaled gradient solution. Simulated BBU threshold (GBBU) vs. HOM frequency spread. 50 mA

14. © I. Ben Zvi R&D ERL Test-bed for eRHIC technology

15. eRHIC – Geometry high-lumi IR with β *=5 cm, l*=4.5 m and 10 mrad crossing angle Q5 D5 Q4 90.08703 m 10 mrad 4.432 mrad 0.32878 m 3.6745 mrad 60.0559 m 10 20 30 0.25573 m 25.5735 m © D.Trbojevic V.N. Litvinenko, ABP Forum, CERN, April 9, 2010 30 GeV e - 325 GeV p Or 125 GeV/u ions Vertical scale is increased 100 fold

16. © D.Trbojevic V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

17. eRHIC – Geometry of low-x IR with β *=25 cm, l*=15 m and 10 mrad crossing angle 0.448 m Q5 D5 Q4 90.0 m 10 mrad 0.328 m 3.67 mrad 60.0 m 10 20 30 0.255 m 25.5 m V.N. Litvinenko, ABP Forum, CERN, April 9, 2010 © D.Trbojevic Vertical scale is increased 100 fold 30 GeV e - 325 GeV p Or 125 GeV/u ions

18. Quads for β *=5 cm © B.Parker

19. eRHIC IR1 p /Ae Energy (max), GeV325/13020 Number of bunches166 74 nsec Bunch intensity (u), 10 11 2.00.24 Bunch charge, nC324 Beam current, mA420 50 Normalized emittance, 1e-6 m, 95% for p / rms for e 1.225 Polarization, %7080 rms bunch length, cm4.90.2 β *, cm25 Luminosity, cm -2 s -1 2.8x 10 33 Luminosity for 30 GeV e-beam operation will be at 20% level eRHIC IR2 p /Ae 325/13020 166 74 nsec 2.00.24 324 420 50 1.225 7080 4.90.2 55 1.4 x 10 34 Luminosity in eRHIC V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

20. Suppression of kink instability Nonlinear force model with Hourglass effect With rms proton energy spread =1e-3 By chromaticity:  ~ +4 Recent studies proved our early assumption (ZDR Appendix A) that using simple feed-back on electron beam suppress kink instability completely for all eRHIC parameter ranges © Y. Hao By feedback RHIC ERL IP BPM Feedback kicker

21. V.N. Litvinenko, ABP Forum, CERN, April 9, 2010 Key ingredients: RHIC with all its species ERL technology 50 mA polarized electron gun Coherent electron cooling Crab-crossing High gradient SM magnets

22. * the Gatling gun is the first successful machine gun, invented by Dr. Richard Jordan Gatling. ©J.Skaritka © E.Tsentalovich, MIT Main technical challenge is 50 mA CW polarized gun: we are building two versions Single large size cathode Gatling gun V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

23. Coherent Electron Cooling (CeC) Amplifier of the e-beam modulation in an FEL with gain G FEL ~10 2 -10 3 vhvh 2 R D// FEL 2 R D  FEL EzEz E0E0 E < E 0 E > E 0 Modulator Kicker Dispersion section ( for hadrons) Electrons Hadrons l2l2 l1l1 High gain FEL (for electrons) EhEh E < E h E > E h Dispersion At a half of plasma oscillation Debay radii Density V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

24. Possible layout in RHIC IP of CeC driven by a single linac for RHIC and eRHIC Gun 1 Gun 2 Beam dump 1 Beam dump 2 ERL dual-way electron linac 2 Standard eRHIC modules E p, GeV  E e, MeV 100106.5854.46 250266.45136.15 325346.38177.00 Modulator for Blue Modulator for Yellow FEL for Blue FEL for Yellow Kicker for BlueKicker for Yellow V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

25. IBS in RHIC for eRHIC, 250 GeV, N p =2. 10 11 Beta-cool,  A.Fedotov This allows a)keep the luminosity as it is b)reduce polarized beam current down to 50 mA (10 mA for e-I) c)increase electron beam energy to 20 GeV (30 GeV for e-I) d)increase luminosity by reducing  * from 25 cm down to 5 cm Dynamics: Takes 12 mins to reach stationary point Gains from coherent e-cooling: Coherent Electron Cooling vs. IBS V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

26. Layout for Coherent Electron Cooling proof-of-principle experiment in RHIC IR Collaboration is opened for all interested labs/people DX 19.6 m Modulator, 4 m Wiggler 7m Kicker, 3 m 20 MeV SRF linac Beam dump Parameter Species in RHICAu ions, 40 GeV/u Electron energy21.8 MeV Charge per bunch1 nC Train5 bunches Rep-rate78.3 kHz e-beam current0.39 mA e-beam power8.5 kW 26 V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

27. Polarizing Hadron Beams with Coherent Electron Cooling New LDRD proposal at BNL: VL & V.Ptitsyn Modulator Kicker Delay for hadrons Electrons Hadrons l2l2 High gain FEL (for electrons) HW1 left helicity HW2 right helicity Modulation of the electron beam density around a hadron is caused by value of spin component along the longitudinal axis, z. Hardons with spin projection onto z-axis will attract electrons while traveling through helical wiggler with left helicity and repel them in the helical wiggler with right helicity. The high gain FEL amplify the imprinted modulation. Hadrons with z-component of spin will have an energy kick proportional to the value and the sigh if the projection. Placing the kicker in spin dispersion will result in reduction of z- component of the spin and in the increase of the vertical one. This process will polarize the hadron beam

28. Polarizing Hadron Beams with Coherent Electron Cooling It is very provocative proposal and requires very high gain FELs for attaining reasonable spin-cooling times – no time to go into many details For LHC this technique could an unique opportunity to operate with polarized hadrons in RHIC, bringing polarization of proton beams close to 100% would provide for a nearly eight-fold boost of the observables and could be of critical for solving long-standing proton spin crisis The methods can be used for polarizing other hadrons, such as deuterons – polarization of which is considered to be impossible in RHIC, He3 and other ions The technique can open a unique possibility of getting polarized antiprotons V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

29. Coherent-electron-Cooling would provide following for linac-ring LHeC Smaller proton beam emittance down to 0.2 mm mrad Can provide shorted bunches down to 1 cm (if needed) Allows to reduce electron beam current 20-fold to achieve of e-p luminosity above 10 34 level with 60 GeV electrons and 7 TeV protons V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

30. Sample of CeC for LHeC LHCCooling time Circumference26658.883mFull bunch0.346hrs Main ParametersCeCLocal176.27sec Modulator Length70mLength of the system153.70m Kicker length35mFEL length48.70m Peak current, e100.0AFEL gain length3.08m Amplification1000.00 Wavelength10nmFEL formulaTRUE w 5cmChecksTRUE FEL bandwidth0.02 I will use conservative 0.8 hrs cooling time V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

31. Evolution of beam in LHC at 7 TeV (assuming nominal LHC bunch intensity 1.15e11 p/bunch and 40% of CeC cooling capability) IBS rates in LHC from Table 2.2 Stationary solution for τ CeC = 0.8 hrs J.LeDuff, "Single and Multiple Touschek effects", Proceedings of CERN Accelerator School, Rhodes, Greece, 20 September - 1 October, 1993, Editor: S.Turner, CERN 95-06, 22 November 1995, Vol. II, p. 573 V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

32. Layout for ERL based LHC Hadrons – 1.15e11 per bunch – Cooled by CeC Electron – Accelerated in the ERL - 60 GeV – Polarized electron beam current - 8 mA Number of passes – 3 AC power consumption – 100 MW Crab-crossing β *=12 cm L = 2. 10 34 cm -2 sec -1 R=700m 10 GeV linac 0.5 GeV ERL-injector Dump Gun V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

33. Conclusions We focused again of all-in-the-tunnel staging of eRHIC In addition to previous solid design of low-X IR, we had developed high luminosity IR with L >10 34 using advances in the SM quad technology and in the crab-crossing We aggressively pursue development of polarized Gatling gun and develop specific plans for testing Coherent Electron Cooling at RHIC Using eRHIC-style ERL and CeC for 60 GeV x 7 TeV LHeC promises providing L >10 34 with power consumption below 100 MW and modest size of facility V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

34. Back-up V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

35. LHeC V.N. Litvinenko, ABP Forum, CERN, April 9, 2010 Radius,  CryoRF mainRF SRMagnetsTotalPasses 500.00 MW 2 x 7.5 GeV linacs18.5616.6760.25499.484 2 x10 GeV linacs24.7522.2246.08396.053 2 x 15 GeV linacs37.1333.3332.402104.862 30 GeV linac, dogbone37.1333.3348.173121.63DGBN LHC protons Energy7TeV  _p 7.46E+03 N_p1.70E+11 No Cooling Emittance, norm3.75mm mrad Emittance5.03E-01nm rad Allowable tune shift0.01 Maximum # of e3.07E+11 Rep-rate2.00E+07Hz I max9.84E-01A Realistic0.008A N real2.50E+09 Room for improvement1.23E+02 ** 0.12m  7.58E-10m^2 L/h1.12E+33 With cooling Emittance, norm0.2mm mrad Emittance2.68E-02nm rad Allowable tune shift0.01 Maximum # of e1.64E+10 Rep-rate2.00E+07Hz I max5.25E-02A Beam current0.008A N real2.50E+09 Room for improvement6.56E+00 ** 0.12m  4.04E-11m^2 L/h2.10E+34

36. V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

38. ©Dejan Trbojevic Integrated high-Q IR design, β *=5cm First quadrupole is 4.5 m from IP Plan to use newly commissioned (last month!) LARP SC quads with 200 T/m gradient Nb 3 Sn May be used for luminosity hungry experiments Will work with the Alan Caldwell detector Or a JLab type one L=1.4x10 34 V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

39. Additional advantage of linac-ring – removing systematic errors It is built-in feature of the linac-ring eRHIC: we can arbitrary select polarization of individual bunches a)In RHIC this is already implemented by injection scheme (ion source) for protons b)In eRHIC ERL electron polarization is reversible by switching helicity of the laser photons protons electrons It is impossible in ring-ring EIC © D. Lowenstein V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

40. Disruption for eRHIC Optimization β*= 1m Emittance: 1nm-rad β*= 0.2m Emittance: 5nm-rad V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

41. e-Beam Disruption – used bunches are discarded protons e MeRHIC eRHIC ©Y. Hao

42. Incorporating eSTAR and ePHENIX Without changing DX-D0 both the energy and luminosity will be low in electron-hadron collisions Parallel operation of hadron-hadron and electron-hadron collisions does not allow cooling of hadron beam, hence 10-fold lower luminosity for e-p and e-A Sequential operation of RHIC as a hadron collider and as an electron- hadron collider allows to have both full energy and full luminosities in al modes of operation, including coherent electron cooling Coherent Electron Cooling would provide 10-fold increases in e-p amd e-A luminosities (and 6-fold increase in polarized p-p luminosity) We have designs of two IR: low-x (L~3. 10 33 ) and high-lumi (L~2. 10 34 ) We suggest using crossing angle and ±5 mrad crab-cavities to have identical energy-independent geometry of IRs and no synchrotron radiation in detectors V.N. Litvinenko, ABP Forum, CERN, April 9, 2010