1. The RHIC Optically-Pumped Polarized Ion Source. The OPPIS polarization technique. Sona-transition studies. OPPIS performance in 2006-07 Runs. Pulsed OPPIS development. Anatoli Zelenski, BNL PSTP 2007, Brookhaven National Laboratory

2. Workshop on high –energy spin physics, Protvino, IHEP, September,1983 Workshop on high –energy spin physics, Protvino, IHEP, September,1983 Yaroslav Derbenev “Siberian snake” proposal. A new polarized source technique. Equal intensity for polarized and unpolarized proton beams.

3. STAR PHENIX AGS LINAC BOOSTER Pol. H - ion source Spin Rotators 20% Snake Siberian Snakes 200 MeV polarimeter RHIC pC “CNI” polarimeters RHIC Absolute H-jet polarimeter Design goal - 70% Polarization, L max = 1.6  10 32 s -1 cm -2, 50 < √s < 500 GeV AGS pC “CNI” polarimeter 5% Snake Polarization facilities at RHIC.

4. Optically-Pumped Polarized H - Ion Source at RHIC. RHIC OPPIS produces reliably 0.5-1.0mA (maximum 1.6 mA) polarized H - ion current. Pulse duration 400 us. Polarization at 200 MeV P = 85-90 %. Beam intensity (ion/pulse) routine operation: Source - 10 12 H - /pulse Linac (200MeV) - 5∙10 11 Booster - 2∙10 11, (50% - scraping). AGS - 1.7∙10 11 RHIC - 1.5∙10 11 (p/bunch). The RHIC OPPIS was developed in collaboration with TRIUMF and INR, Moscow.

5. Polarization in the BNL OPPIS vs. Rb vapor thickness. TRIUMF 1999. 1.6 mA H - Current P=90% Pulsed laser 1.6 mA H - Current P=90% Pulsed laser DC laser optical pumping

6. Polarized H - ion current pulse out of 200 MeV linac. Faradey rotation polarization sinal. 500 uA cuurent At 200 MeV. 85-hole ECR Source for the maximum polarization. 400 uS 12·10 11 -polarized H - /pulse.

7. Present LEBT & MEBT Optics box 750 keV MEBT 35 keV LEBT LSP- Lamb shift polarimeter. Faraday rotation polarimeter.

8. Polarized injector, 200 MeV linac and injection lines. OPPIS 200 MeV polarimeter Polarization direction is adjusted vertically in the 750 keV beamline by the solenoidal spin - rotator. 200 MeV linac

9. SPIN -TRANSFER POLARIZATION IN PROTON-Rb COLLISIONS. Rb + H+H+ H+H+ Proton source Laser-795 nm Optical pumping Rb: NL(Rb) ~10 14 cm -2 Sona transition 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 Rb +

10. SCHEMATIC LAYOUT OF THE RHIC OPPIS. 29.2 GHz ECR proton source 29.2 GHz ECR proton source SCS solenoid Probe laser Na-jet Ionizer cell Na-jet Ionizer cell Pumping laser Cryopumps Correction coil Sona-shield Rb-cell SCS -solenoid

11. ECR - primary proton source. 1-quartz liner Ø40 мм; 2- ECR-cavity; 3-three-grid multihole proton extraction system; 4- boron-nitride cups; 5-”Kalrez” O-rings. Longitudinal magnetic field distribution for optimal OPPIS operation. Microwave guide 800 W @ 29.2 GHz Magnetic field in the ECR region 24.5 KG Probe laser window 10 kG

12. Magnetic field maps for Oxford Instr. and Toshiba solenoids. Toshiba solenoid Oxford solenoid Bz -field component at the solenoid axis. Z- RF-power input Rb-cell ECR-grids Sona-transition Correction coil

13. Proton polarization vs. Rb vapor thickness. Long Rb cell A new short Rb cell Rb cell upgrades: A new vacuum chamber. A new cooling system. A new deflecting plates. H + + Rb H 0 - polarized H 2 H 0 - unpolarized

14. Optical pumping of Rb charge-exchange vapor cell. Rb h Proton beam. 28 mm Optical pumping by σ +: Δm J =1 Spontaneous radiation: Δm J =0, 1. m J -1/2 +1/2 Rb pol. Profile. Rb vapor cell. 795 nm

15. A new semiconductor probe laser “Toptica” laser 150 mW at 780 nm for Faraday rotation polarimeter. OPPIS laser system for optical pumping and Faraday rotation polarization measurements. Optical pumping: Cr:LISAF –crystall -795 nm Flash-lamp pumping

16. Faraday rotation polarimeter of Rb vapor. Θp-optical pumping –on. Θ 0 -optical pumping -off. PD1 PD 1 =I 0 sin θ p PD 2 =I 0 cos θ p P Rb = ( θ p - θ 0 )/  θ 0 PD2 Cr:LISAF pumping laser at795 nm Rb-cell λ/2 Linear polarized probe laser beam at 780 nm.

17. 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

18. 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 H 0 – 3 keV

19. Bz-field component in the Sona-transition region. Sona-shield Soft steel cylinder Mu-metal incert. Na-jet - dBz/dZ<< 0.2 G/cm Correction Coil Multiple charge-exchange: H 0 H - H 0 H -

20. SONA-TRANSITION. Polarization transfer from electrons to protons. Sona- transition ECR-zone Correction coil Steel plate

21. Calculated magnetic field profiles in the Sona transition region. Sona - shield Correction coil currents correspond to polarization oscillation peaks. B r = r/2 ∙dB z /dZ, ω L ∙B∙t= 2 π ∙28∙10 9 B r ∙t ~ 2 π π - flip

22. Polarization oscillations in the Sona-transition, Run - 07. 85% Polarization at 200 MeV vs. Correction Coil current 50 A After Sona-transition upgrade, Run 07 Simulations and field measurements. A new diam. 4.0” Sona-shield A new Correction Coil Optimized positions for shield and CC

23. Polarization in the Lamb-shift polarimeter.

24. Correction coil scan. 12 mm collimator Ionizer -250 A, 1.8 kG Correction coil scan. 12 mm collimator Ionizer -250 A, 1.8 kG

25. Polarization vs. ionizer solenoid current with the 12mm collimator. Maximum polarization from the correction coil scans, collim. -12 mm. 160 A ↔1.16 kG, 81.6% (95.9%) 200 A ↔1.45 kG, 84.9% (97.0%) 250 A ↔1.81 kG, 88.1% (98.1%) Maximum polarization from the correction coil scans, collim. -12 mm. 160 A ↔1.16 kG, 81.6% (95.9%) 200 A ↔1.45 kG, 84.9% (97.0%) 250 A ↔1.81 kG, 88.1% (98.1%) Theoretical limit 23 mm collimator. 200 A ↔1.45 kG, 82.5% (97.0%) 250 A ↔1.81 kG, 84.5% (98.1%) A new ionizer solenoid: 250 A ↔1.98 kG, 90.0% (98.4%) 23 mm collimator. 200 A ↔1.45 kG, 82.5% (97.0%) 250 A ↔1.81 kG, 84.5% (98.1%) A new ionizer solenoid: 250 A ↔1.98 kG, 90.0% (98.4%) Theoretical limit

26. Bz-field component in the Sona-transition region. Sona-shield Soft steel cylinder Mu-metal incert. Na-jet - dBz/dZ<< 0.2 G/cm Correction Coil Multiple charge-exchange: H 0 H - H 0 H -

27. Depolarization caused by incomplete hyperfine coupling breakdown in the ionizer magnetic field (E ioniz ). P = P 0 (1 + x /√1 +x 2 )/2 X = B / Bc, Bc = 507 G – critical field. x 12345 B, G5081016152320302538 P, %85.494.797.498.599.0 ΔE n, π∙mm∙mrad 0.8 0.29 1.6 0.58 2.4 0.87 3.2 1.15 4.0 1.44 R=1.0 cm R=0.6 cm ΔE n –normalized emittance growth associated with charge exchange in the magnetic field.

28. 85% Polarization measurements in 200 MeV polarimeter.

29. Polarization measurements at 200 MeV.

30. 91.2+/-1.5%

31. Polarization measurements in RHIC at 100 GeV.

32. BNL OPPIS reliably delivered polarized H - ion beam (P= 82-86%) in the 2006 run for the RHIC spin program. A beam intensity greatly exceeds RHIC bunch intensity limit, which allowed strong beam collimation in the Booster, to reduce longitudinal and transverse beam emittances. 85-90% polarization was achieved at further Sona-transition optimization and ionizer magnetic field increase in Run 07. OPPIS operation in Runs 2006-07 Further improvements: A higher brightness primary proton beam is required for high intensity source with the smaller diameter collimated beam in Sona-transition and ionizer (which is necessary for high polarization).

33. Proton “cannon” of the atomic H injector. The source produced 3 A ! pulsed proton current at 5.0 keV. ~20-50 mA H - current. P=75-80% ~10 mA, P  90%. ~ 300 mA unpolarized H - ion current. Ion Optical System with “geometrical focusing”.

34. OPPIS with the “Fast Atomic Beam Source” layout. He –ionizer cell serves as a proton source in the high magnetic field. H0H0 H2 neutralizer cell Rb cell Proton source

35. Pulsed OPPIS at TRIUMF, 1999. Atomic H injector. Beam energy, keV2.03.04.0 H - ion current, mA5.08.014.0 Proton current, mA16.050.0 Polarization, %55± 542± 530 ±5

36. Beam intensity and polarization in the pulsed OPPIS, TRIUMF 1999. Beam energy, keV2.03.04.0 H - ion current, mA5.08.014.0 Proton current, mA16.050.0 Polarization, %55± 542± 530 ±5 10 kG 25 kG

37. OPPIS with the “Fast Atomic Hydrogen Source” (Towards 100% polarization in OPPIS). Higher polarization is also expected with the fast atomic beam source due to: a) elimination of neutralization in residual hydrogen; b) better Sona-transition efficiency for the smaller ~ 1.5 cm diameter beam; c) use of higher ionizer field (up to 3.0 kG), while still keeping the beam emittance below 2.0 π mm∙mrad, because of the smaller beam – 1.5 cm diameter. All these factors combined will further increase polarization in the pulsed OPPIS to: over 90% and the source intensity to over 10 mA. ( A new superconducting solenoid is required). The ECR-source replacement with an atomic hydrogen injector will provide the high intensity and high polarization beam for polarized RHIC luminosity upgrade and for future eRHIC facilities.

38. Polarized beams in RHIC. OPPIS LINAC Booster AGS RHIC 1.5-1.7 p/bunch, P ~65-70% 10∙10 11 (maximum 40∙10 11 ) polarized H - /pulse, P =85% 5∙10 11 polarized H - /pulse at 200 MeV, P=85% 2∙10 11 polarized protons /pulse at 2.3 GeV Maximum RHIC bunch intensity ~1.5 10 11 p/bunch Polarization - 65%.

39. Depolarization in the Sona-transition (E Sona ). W m J m I m F ½ ½ 1 ½ -½ 0 -½ -½ -1 -½ ½ 0 -½ m J m I ½ -½ F=0 F=1 0 Bs<<B R ~ R (dB/dZ) << 2 G/cm – limitation on Bz gradient and beam B Z =0 size at the zero crossing point (diabatic crossing).

40. Depolarization factors in the OPPIS. Depol. Factor ProcessEstimate P Rb Rb polarization0.98 - 0.99 SRb polarization spatial distribution0.97 - 0.98 B H2 Proton neutralization in residual gas.0.94 - 0.97 E LS Depolarization due to spin-orbital interaction.0.98 - 0.98 E S Sona-transition efficiency0.96 - 0.99 E ioniz. Incomplete hyperfine interaction breaking in the ionizer magnetic field. 0.95 - 0.98 MPolarization dilution by molecular hydrogen ions in the ECR source. 1.00 –1.00 Total: 0.82 - 0.90 (0.9/0.8) 4 ~1.6 P = P Rb ∙ S ∙ B H2 ∙ E LS ∙ E Sona ∙ E ion ∙ M ~ 85-90%

41. Sona-transition upgrades. A new 4.0” diameter Sona- shield, with mu-metal insert, to reduce field gradient at the shield entrance. A new smaller diameter Correction Coil to localize field spread. Ionizer solenoid moved for 1.0 “ further from Sona shield. Smaller diameter collimators: 20mm, 15 mm, 12 mm. Steel plate at the SCS to reduce the field propagation. Longitudinal deflecting plates ?!.

42. OPPIS Lamb-shift polarimeter. He-ionizer cell Na-cell, spin-filter and L  detector are placed inside the vacuum chamber.

43. Proton Lamb-shift polarimeter. H - → H + → H(2S) B=575 G L  –photons 121.6 nm. H(2S)