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First Experiments with the Polarized Internal Gas Target (PIT) at ANKE/COSY

Ralf Engels for the ANKE-Collaboration Institut für Kernphysik, Forschungszentrum Jülich. First Experiments with the Polarized Internal Gas Target (PIT) at ANKE/COSY. Brookhaven September 14, 2007. Outline. Introduction PIT installation Setup overview

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First Experiments with the Polarized Internal Gas Target (PIT) at ANKE/COSY

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  1. Ralf Engels for the ANKE-Collaboration Institut für Kernphysik, Forschungszentrum Jülich First Experiments with the Polarized Internal Gas Target (PIT)at ANKE/COSY Brookhaven September 14, 2007

  2. Ralf Engels Outline Introduction PIT installation Setup overview Transfer to COSY hall and installation at ANKE PIT commissioning Stray fields at ANKE Cell tests at ANKE Target commissioning Results Plans for the future

  3. Ralf Engels COSY – COoler SYnchrotron p, p, d, d with momenta up to 3.7 GeV/c • internal experiments – with the circulating beam • external experiments – with the extracted beam

  4. Ralf Engels ANKE at COSY Magnets • D2 – spectrometer magnet • D1, D3 – beam bending magnets Detector systems • Positive & Negative • Forward & Backward • Spectator Detectors Targets • Solid strip • Cluster jet • Polarized internal target PIT ( storage cell or jet ) Spectrometer ANKE

  5. Ralf Engels PIT at ANKE 3D CAD drawing of PIT at ANKE ABS Technical constraints • Target exchange within a maintenance week • New support bridge, following the movement of D2 magnet • Magnetic shielding of components • of the Atomic Beam Source (ABS) • (D2 Magnet: 1.6 Tesla) Storage cell Polarimeter

  6. Ralf Engels Polarized Internal Gas Target Main parts of a PIT: • Atomic Beam Source • Target gas hydrogenordeuterium • H beam intensity (2 hyperfine states) 7.6 . 1016 atoms / s • Beam size at the interaction point σ = 2.85 ± 0.42 mm • Polarization for hydrogen atoms PZ = 0.89 ± 0.01 PZ = -0.96 ± 0.01 • Lamb-Shift Polarimeter • Target chamber with Storage Cell ABS and LSP at the laboratory

  7. Ralf Engels The Lamb-shift Polarimeter

  8. Ralf Engels The Molecules in the ABS jet I H + = 0.029 ± 0.002 2 I H + c · I p + Engels et al.; RSI 76, 053305 (2005) 2

  9. Ralf Engels ABS and LSP in the COSY hall December 2004– transfer to COSY hall (outside of the COSY tunnel) May 2005 – tests after reassembling • Supports representing D1 and D2 • New support bridge • Platform for all electronic and supply components • Heat exchanger with closed cooling-water circuit June 2005 –setup ready for installation at ANKE Setup in the COSY hall

  10. Ralf Engels PIT installation at ANKE Platform transportation ABS transportation

  11. Ralf Engels PIT at ANKE

  12. Ralf Engels Magnetic stray field of D2 40 26 300 90 150 135 30 33 55 30 25 55 200 550 300 6 15 30 y z x 60 100 300 calculated field strength (G) measured field strength (G) permissible field strength for the device given by the producer(G) PIT setup with shielded components at ANKE

  13. Ralf Engels Test of the medium-field rf transition unit MFT off (HFS 1 and 2) MFT on (HFS 1 only) no ABS beam

  14. Ralf Engels Do we have a zero field crossing ? Magnetic field scan with ANKE at 5.3º using a 3D Hallprobe (Gatchina): Magnetic field along ABS axis • ID2=563 A (~ 0.6 T) • ID1D3=1294.84 A Bx By By |B| Determine the local Larmor precession frequency ωL The angular velocity of the magnetic field ωB. As long as the ratio R=ωL/ωB is large, the spin of the atom follows the field direction. → no depolarization due to zero crossings ωL R=ωL/ωB ωB

  15. Ralf Engels Tuning of the Transition Units • Supporting bridge between D1 and D2 • Additional shielding from the D2 stray fields • Cryopump at the target chamber • Polarimeter ionizer under the target chamber

  16. Ralf Engels First Polarization Measurement with the LSP WFT was tuned online at the ANKE target position near the D2 magnet. The measured asymetry was stable during the beam time. Problems: - The magnetic stray field of the D2 magnet deflected the produced protons. - The quantization axis was rotated by the stray field and the LSP measures only the projection on the horizontal beam line. Next time: More shielding and a rotatable Wien filter to compensate the misalignment of the polarization axis!

  17. Ralf Engels The ABS jet target Without ABS jet With ABS jet Without catcher 4.0·10-9 3.0·10-7 With catcher 4.0·10-9 3.7·10-8 ABS jet Measured pressures in the target chamber, mbar COSY Beam integralthickness ~ 1.5 . 1011 cm-2 ~13cm ABS-jet density, cm-3 ABS beam catcher

  18. Ralf Engels Storage cell setup XY-table Target chamber Frame with storage cell and aperture 400mm COSY beam Feeding tube: l = 120 mm, Ø = 10 mm Extraction tube:l = 230 mm, Ø = 10 mm Beam tube : l = 400 mm, 20x20 mm2

  19. Ralf Engels The COSY beam size at injection 15 x 15 mm2 36x16 mm with an accelerated beam 9x12 mm 16x15 mm with cluster target (density ~ 1014 at/cm2) no target

  20. Ralf Engels Storage cell: Final setup for the 1. Experiment • Tools for the experiment • New storage cell & support (20•20•390 mm) > high target density > unpolarized gas feeding system • LSP below the target chamber > online measurement of the ABS beam polarization • Silicon Tracking Telescope (STT) > measurement of spectator protons nearby the storage cell center

  21. Ralf Engels Cooler stacking with the storage cell 28 stacks followed by • 2s electron cooling • after 58s acceleration toTp=600 MeV Cooler Stacking allows for higher polarized beam intensities with cell. Without storage cell 2.5·1010 ions were reached.

  22. Ralf Engels Results of the cell tests ΘANKE injection type target number of stored protons * 10 9 injection after cooling flattop (600 MeV) 0º single injection no cell 83 21 14 single injection empty cell 7 5 3.5 80 stacking + electron cooling no cell 26 30 stacking + electron cooling empty cell 20 9.2º 30 stacking + electron cooling empty cell 6 cell with H gas from ABS 30 stacking + electron cooling 9.2º 9 6.4

  23. Ralf Engels Storage cell and stochastically cooled beam Cooling off Tp= 831 MeV Cooling on

  24. Ralf Engels First Experimental Beam Time 0 20 50 Time, min Stacking → 120 injection with 10 s e-cooling Flat top→ 30 min, to have about 60 % duty time

  25. Ralf Engels First Experimental Beam Time Acceleration without gas in the storage cell Switching on the gas to feed the storage cell 0 20 50 Time, min Stacking → 120 injection with 10 s e-cooling Flat top→ 30 min, to have about 2/3 duty time 7 · 109 polarized deuterons in the ring with gas in the target

  26. → → → → dp, First Double Polarized Experiment: dp Td=1.2 GeV, target H (N2) gas dp→dp Ralf Engels

  27. First Double Polarized Experiment: dp → → → → dp, Td=1.2 GeV, target H (N2) gas High branch dp→(dpsp)πo quasi-free np→dπo (High & Low branch) Low branch Ralf Engels

  28. First Polarization Measurement of the Target → dp, Td=1.2 GeV, polarized H gas θd=50-150 θd=150-220 θd=220-280 θd=280-400 quasi-free np → dπ0 (High and low branch) <Qy> = 0.79 ± 0.07 quasi-free np→dπo (High & Low branch) <Qy> = 0.75 ± 0.06 θd=1550-1650 θd=1650-1700 θd=1700-1770 ANKE preliminary Ralf Engels

  29. Ralf Engels Summary of commissioning and first experiment • Tests at ANKE with ABS and storage cell with stacking injection (Nov. 2005) and stochastic cooling (Mar. 2006) →→ • First experiment dp→ppn - Jan./Feb. 2007 1.Cell-targetthicknessfor H (hyperfine state 1) ~ 2 · 1013 cm-2 2. Average luminosity for the storage-cell test ~ 1 · 1029 cm-2 s-1 3. ABSjet-targetthickness~ 1.5 · 1011 cm-2 4. Hydrogen polarization in the cell~ 0.79 +/- 0.07

  30. Ralf Engels Plans for the future December '07 – PIT reinstallation: With rotatable Wien filter and better shielding of the LSP Jan./Feb. ’08–Next beam time: d p→ (pp)n at 2.435 – 3.7 GeV/c (5 Weeks) March ’08 – PIT deinstallation ABS and LSP can be used for other experiments: - ISTC project 1860: Nuclear Polarization in H2/D2 molecules - Direct Measurements of the Hyperfine levels in the 2S1/2/2P1/2 state → Breit-Rabi diagram → →

  31. Ralf Engels Far Future: Polarized Fusion

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