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

2. Ralf Engels2 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. September 14, 2007Ralf Engels3 internal experiments – with the circulating beam external experiments – with the extracted beam p, p, d, d with momenta up to 3.7 GeV/c COSY – COoler SYnchrotron

4. September 14, 2007Ralf Engels4 ANKE at COSY Targets Solid strip Cluster jet Polarized internal target PIT ( storage cell or jet ) Magnets D2 – spectrometer magnet D1, D3 – beam bending magnets Detector systems Positive & Negative Forward & Backward Spectator Detectors Spectrometer ANKE

5. September 14, 2007Ralf Engels5 PIT at ANKE 3D CAD drawing of PIT at ANKE Storage cell Polarimeter 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)

6. September 14, 2007Ralf Engels6 Polarized Internal Gas Target Main parts of a PIT: Atomic Beam Source Target gas hydrogen or deuterium H beam intensity (2 hyperfine states) 7.6. 10 16 atoms / s Beam size at the interaction point σ = 2.85 ± 0.42 mm Polarization for hydrogen atoms P Z = 0.89 ± 0.01 P Z = -0.96 ± 0.01 Lamb-Shift Polarimeter Target chamber with Storage Cell ABS and LSP at the laboratory

7. September 14, 2007Ralf Engels7 The Lamb-shift Polarimeter

8. September 14, 2007Ralf Engels8 The Molecules in the ABS jet I H 2 + 2 + + c · I p = 0.029 ± 0.002 Engels et al.; RSI 76, 053305 (2005)

9. September 14, 2007Ralf Engels9 ABS and LSP in the COSY hall December 2004 – transfer to COSY hall (outside of the COSY tunnel) May 2005 – tests after reassembling Setup in the COSY hall 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

10. September 14, 2007Ralf Engels10 PIT installation at ANKE Platform transportation ABS transportation

11. September 14, 2007Ralf Engels11 PIT at ANKE

12. September 14, 2007Ralf Engels12 Magnetic stray field of D2 PIT setup with shielded components at ANKE x y z 90 150 135 6 15 30 25 55 40 26 300 200 550 300 60 100 300 30 33 55 calculated field strength (G) measured field strength (G) permissible field strength for the device given by the producer (G)

13. September 14, 2007Ralf Engels13 Test of the medium-field rf transition unit no ABS beam MFT off (HFS 1 and 2) MFT on (HFS 1 only)

14. September 14, 2007Ralf Engels14 Do we have a zero field crossing ? Magnetic field scan with ANKE at 5.3º using a 3D Hallprobe (Gatchina): B x B y B y |B| Magnetic field along ABS axis I D2 =563 A (~ 0.6 T) I D1D3 =1294.84 A 1.Determine the local Larmor precession frequency ω L 2.The angular velocity of the magnetic field ω B. As long as the ratio R=ω L /ω B is large, the spin of the atom follows the field direction. → no depolarization due to zero crossings ωLωL R=ω L /ω B ωBωB

15. September 14, 2007Ralf Engels15 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. September 14, 2007Ralf Engels16 First Polarization Measurement with the LSP 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! WFT was tuned online at the ANKE target position near the D2 magnet. The measured asymetry was stable during the beam time.

17. September 14, 2007Ralf Engels17 3.7·10 -8 4.0·10 -9 With catcher 3.0·10 -7 4.0·10 -9 Without catcher With ABS jet Without ABS jet ABS beam catcher ~13cm Measured pressures in the target chamber, mbar ABS-jet density, cm -3 integral thickness ~ 1.5. 10 11 cm -2 ABS jet COSY Beam The ABS jet target

18. September 14, 2007Ralf Engels18 Storage cell setup COSY beam XY-tableFrame with storage cell and aperture Target chamber Feeding tube: l = 120 mm, Ø = 10 mm Extraction tube: l = 230 mm, Ø = 10 mm Beam tube : l = 400 mm, 20x20 mm 2 400mm

19. September 14, 2007Ralf Engels19 The COSY beam size at injection with an accelerated beam no target with cluster target (density ~ 10 14 at/cm 2 ) 9x12 mm 16x15 mm 36x16 mm 15 x 15 mm 2

20. September 14, 2007Ralf Engels20 Storage cell: Final setup for the 1. Experiment  Tools for the experiment New storage cell & support (2020390 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. September 14, 2007Ralf Engels21 Cooler stacking with the storage cell 28 stacks followed by 2s electron cooling after 58s acceleration toT p =600 MeV Cooler Stacking allows for higher polarized beam intensities with cell. Without storage cell 2.5·10 10 ions were reached.

22. September 14, 2007Ralf Engels22 Results of the cell tests single injection3.557empty cell 26no cell 80 stacking + electron cooling flattop (600 MeV) after cooling injection empty cell no cell target 9.2º 0º0º Θ ANKE 30 stacking + electron cooling 83 number of stored protons * 10 9 20 30 stacking + electron cooling 1421single injection injection type 30 stacking + electron cooling 9.2º cell with H gas from ABS empty cell 6.4 6 9

23. September 14, 2007Ralf Engels23 Storage cell and stochastically cooled beam Cooling off Cooling on T p = 831 MeV

24. September 14, 2007Ralf Engels24 First Experimental Beam Time Stacking → 120 injection with 10 s e-cooling Flat top → 30 min, to have about 60 % duty time 0 20 50 Time, min

25. September 14, 2007Ralf Engels25 First Experimental Beam Time Stacking → 120 injection with 10 s e-cooling Flat top → 30 min, to have about 2/3 duty time 0 20 50 Time, min Switching on the gas to feed the storage cell Acceleration without gas in the storage cell 7 · 10 9 polarized deuterons in the ring with gas in the target

26. September 14, 2007Ralf Engels26 T d =1.2 GeV, target H ( N 2 ) gas dp→dp dp, → → dp First Double Polarized Experiment: dp →

27. September 14, 2007Ralf Engels27 dp First Double Polarized Experiment: dp → T d =1.2 GeV, target H ( N 2 ) gas dp→(dp sp ) π o quasi-free np→d π o (High & Low branch) High branch Low branch dp, → →

28. September 14, 2007Ralf Engels28 First Polarization Measurement of the Target ANKE preliminary dp, T d =1.2 GeV, polarized H gas quasi-free np→d π o (High & Low branch) = 0.75 ± 0.06 θ d =5 0 -15 0 θ d =15 0 -22 0 θ d =22 0 -28 0 θ d =28 0 -40 0 θ d =155 0 -165 0 θ d =165 0 -170 0 θ d =170 0 -177 0 → quasi-free np → dπ 0 (High and low branch) = 0.79 ± 0.07

29. September 14, 2007Ralf Engels29 Summary of commissioning and first experiment 1. Cell-target thickness for H (hyperfine state 1)~ 2 · 10 13 cm -2 3. ABS jet-target thickness ~ 1.5 · 10 11 cm -2 Tests at ANKE with ABS and storage cell with stacking injection (Nov. 2005) and stochastic cooling (Mar. 2006) 2. A verage luminosity for the storage-cell test ~ 1 · 10 29 cm -2 s -1 4. Hydrogen polarization in the cell ~ 0.79 +/- 0.07 First experiment dp→ppn -Jan./Feb. 2007 →→

30. September 14, 2007Ralf Engels30 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 H 2 /D 2 molecules - Direct Measurements of the Hyperfine levels in the 2S 1/2 /2P 1/2 state → Breit-Rabi diagram →

31. September 14, 2007Ralf Engels31 Far Future: Polarized Fusion