1. The Relativistic Heavy Ion Collider high-intensity polarized H - ion source The Relativistic Heavy Ion Collider high-intensity polarized H - ion source A.Zelenski, G.Atoian, D.Raparia, J.Ritter, D.Steski Brookhaven National Laboratory ICIS 2015, August 28, 2015 Optical pumping polarization technique Charge-exchange collisions High-brightness atomic beam source He-ionizer cell Sodium-jet ionizer cell Summary

2. The old RHIC OPPIS based on ECR primary proton source retired after successful operation in Runs 2000-2012. The new source with atomic beam hydrogen injector and He-ionizer was developed in 2010-12 and commissioned for operation in Run-2013. It produces significantly higher brightness primary proton beam which resulted in higher polarized beam intensity and polarization delivered for injection to Linac-Booster-AGS-RHIC accelerator chain. Practically all OPPIS systems were modified (in addition to the ECR- source): a new superconducting solenoid; new He-ionizer cell with a pulsed He-injection and new pulsed electro-magnetic gas valve; beam energy separation system developed for un-polarized residual beam suppression; new vacuum system with turbo-molecular pumps for He-pumping; laser control, diagnostics and transport systems.

3. The RHIC OPPIS upgrade with atomic hydrogen injector, Run-2013-15 BNL - BINP, Novosibisk -INR, Moscow collaboration

4. STAR PHENIX AGS, 24GeV LINAC BOOSTER, 2.5 GeV Pol. H - ion source Spin Rotators Siberian Snakes 200 MeV polarimeter RHIC pC “CNI” polarimeters RHIC Absolute H-jet polarimeter L max = 1.6  10 32 s -1 cm -2 50 < √s < 510 GeV AGS pC “CNI” polarimeter Polarization facilities at RHIC

5. OPPIS LINAC Booster AGS RHIC (2.0-2.5) ∙10 11 p/bunch 1.0 mA x 300us→18∙10 11 polarized H - /pulse. 9.0 ∙10 11 polarized H - /pulse at 200 MeV routinely in Run-15 (2.5-3.0) ∙10 11 protons /pulse at 2.3 GeV ~1.8∙10 11 p/bunch, P~60-65% at 100 GeV P ~ 58% at 255 GeV RHIC Polarized beam in Run 2013-15 It is expected, that use of Electron Lens will allow increase of the bunch intensity to ~2.5∙10 11 p/bunch.

8. What can we learn about “swiss” watches from watches collisions? Actually a lot! In particular, if protons are polarized!

9. Intermediate bozons W ± - can be produced directly in electroweak processes in collisions of polarized proton beams of a 250 GeV energy at RHIC. In this case parity-violation can be as large as 50% and spin-correlation can be used for studies of different flavor quark contribution to the proton spin.

10. SPIN -TRANSFER POLARIZATION IN PROTON-Rb COLLISIONS Rb + H+H+ H+H+ Proton source Proton source Laser-795 nm Optical pumping Rb: NL(Rb) ~10 14 cm -2 Sona transition Sona transition Ionizer cell Ionizer cell H-H- Laser beam is a primary source of angular momentum: 10 W (795 nm) 410 19 h /sec 2 A, H 0 equivalent intensity. Supperconducting solenoid 25 кГс 1.5 kG field Charge-exchange collisions:  ~10 -14 cm 2 Na-jet ionizer cell: NL(Na)~ 310 15 cm -2 Electron to proton polarization transfer ECR-29 GHz Н + source ~50 mA, 2.8keV Rb +

11. Optical Pumping polarization technique. A. Kastler, Nobel prize 1966 5S 1/2 5P 1/2 λ = 795 nm Circularly Polarized light M J = -1/2 M J = +1/2 Spontaneous decays. nL J ~ 100% polarized Rb atoms! 1.56 eV relaxation Optical pumping application is limited by available laser power!? Recent progress in laser technology is very promising for new applications. M J = +1/2 M J = -1/2

12. Pulsed OPPIS with the atomic hydrogen injector at INR, Moscow, 1982-1990. First generation Atomic H 0 injector Helium ionizer cell ~80% ionization efficiency. Lamb-shift polarimeter H - current- 0.4mA H + current- 4.0 mA, P=65%, 1986

13. New generation OPPIS with atomic H 0 injector Atomic H injector He-cell H-H- High-brightness proton beam inside strong 2.5 T solenoid field produced by atomic H beam ionization in the He-gas ionizer cell The proton beam intensity is about 1.0 A !

14. Hydrogen atomic beam ionization efficiency in the He- cell 10 keV 80% H 0 + He → H + + He + e

15. “Fast Atomic Beam Source”, BINP, Novosibirsk, 2012 Plasmatron 4-grid proton extraction system H2 Neutralization cell ~ 3.5 A equivalent H 0 beam FABS produces 200-300 mA equivalent H0 beam intensity Within the Na-jet ionizer acceptance.

16. FABS 4-grid spherical Ion Optical System 3-5 A of proton beam At 6-8 keV energy 1820 holes, 1.0 mm in diameter

17. FABS and neutralizer cell.

18. Neutral hydrogen beam intensity profile at 250 cm distance from the source. FWHM ~ 20 mm

19. Residual un-polarized H 0 beam component suppression by the energy separation H + (70%) H 0 (6.5 keV) H 0 (2.5 keV) -4.0 kV-4.1 kV H 0 (6.5keV) He-ionizer cell Rb -cell H 0 (30%) Deceleration H 0 + He → H + + He + e -2-3 kV+0.1kV

20. He-ionizer cell and 3-grid energy separation system. He-pulsed valve 3-grid beam deceleration system

21. “Electro-magnetic” valve operation principle. Force to the conducting plate in the (high ~ 3 T) magnetic field. For I=100 A, L=5 cm, F=15 N). I B F

22. New OPPIS with atomic H 0 injector layout, 2013 Rb-cell H+H+ H0H0 H+H+ H0H0 H-H- H2HeRbNa CP1 Na-jet cell Atomic H injector He-ionizer cell Neutralizer H 2 -cell TMP1 Rb-cell Sona transition

23. H - yield vs. H0 beam energy.

24. Sodium-jet ionizer cell Reservoir– operational temperature. Tres. ~500 о С. Nozzle – Tn ~500 о С. Collector- Na-vapor condensation: Tcoll.~120 о С Trap- return line. T ~ 120 – 180 о С. Transversal vapor flow in the N-jet cell. Reduces sodium vapor losses for 3-4 orders of magnitude, which allow the cell aperture increase up to 3.0 cm. Transversal vapor flow in the N-jet cell. Reduces sodium vapor losses for 3-4 orders of magnitude, which allow the cell aperture increase up to 3.0 cm. Nozzle 500deg.C Collector ~150 deg.C Reservoir ~500 deg.C NL ~2·10 15 atoms/cm 2 L ~ 2-3 cm

25. H - beam acceleration to 35 keV at the exit of Na-jet ionizer cell Na-jet cell is isolated and biased to – 32 keV. The H - beam is accelerated in a two-stage acceleration system. -32 kV H - 35 keV 39 keV -28 keV-15 keV 3 keV 7 kev H0H0

26. H - beam acceleration to 35 keV at the exit of Na-jet ionizer cell. Na-jet cell is isolated and biased to – 32 keV. The H - beam is accelerated in a two-stage acceleration system. -32 kV H - 35 keV -28 keV-15 keV

27. Low Energy Beam Transport line. Variable collimator In DB2 to improve Energy resolution. Lamb Shift Polarimeter FC4 35.0 keV FC-Tk1, 750keV OPPIS 23.7 deg bender RFQ

28. Energy separation of decelerated (“polarized”) H - ion beam in LEBT. 31.5 kV 31.5 + (7.5 – 4.0) = 35 keV 1400/30=47

29. 06 Dec, 2013 Note#31,page75 BeamEnergy=6.5keV; IONZ=220A; Polarized H - current at 750 keV energy (after RFQ) vs. Rb-cell temperature NL~10×10 13 atoms/cm 2 Rb cell temperature, deg. C 1.0 mA × 300 us =18×10 11 ions/pulse 12uA

30. Polarized H - current-1.05 mA, after RFQ 750 keV Rb-98º 100 us/div 200 uA/div

31. Rb-90, 200 MeV, T9-620uA 600 µA × 400 µs →14.4 ∙10 11 protons/pulse

32. Polarization (at 200 MeV) vs. SCS magnetic field in He and Rb-cells Magnetic field,kG

33. Source intensity and polarization. Rb-cell thickness-NL 4.5 5.5 7.5 10.4 Linac Current, μA 500 560 680 750 Booster Input ×10 11 9.0 10.0 12.213.5 Pol. %, at 200 MeV 84 83 80.5 78 Reliable long-term ∙operation of the source was demonstrated. Very high suppression of un-polarized beam component was demonstrated. Small beam emittance (after collimation for energy separation) and high transmission to 200 MeV. Rb-cell thickness,NL ×10 13 atoms/cm 2

34. H - beam current and polarization at 200 MeV vs. Rb vapor thickness Rb-vapor thickness –nL –atoms/cm 2 H - ion beam current (mA) Polarization in 200 MeV polarimeter

35. Equal 12 deg and 16 deg polarization numbers Polarization at 200 MeV -85.2%

36. Long-term polarization stability, April 14-23, 2014 86%

37. Polarization in AGS, 23 GeV

39. Polarization measurements at 255 GeV in H-jet polarimeter, Run-2013, April-25-30 < ~ 62% in collisions

40. High intensity polarized proton sources makes feasible the high luminosity RHIC operation to study:  spin proton structure,  fundamental tests of QCD and electro- weak interaction.

41. Summary The old RHIC OPPIS based on ECR primary proton source was retired after successful operation in Runs 2000-2012. The new source with atomic beam hydrogen injector and He- ionizer was developed in 2010-12 and commissioned for operation in Run-2013. It produces significantly higher brightness primary proton beam which resulted in higher polarized beam intensity and polarization delivered for injection to Linac-Booster-AGS-RHIC accelerator chain. Practically all OPPIS systems were modified (in addition to the ECR-source): a new superconducting solenoid; new He- ionizer cell with a pulsed He-injection and new pulsed electro- dynamic gas valve; beam energy separation system developed for un-polarized residual beam suppression; new vacuum system with turbo-molecular pumps for He-pumping; laser control, diagnostics and transport systems.