Commissioning of the Polarized Internal Gas Target (PIT) of ANKE at COSY Ralf Engels Institut für Kernphysik, Forschungszentrum Jülich Tbilisi September 4, 2006 CGSWHP'06 Ralf Engels 1
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 CGSWHP'06 Ralf Engels 2
COSY COoler SYnchrotron r r p, p, d, d with momenta up to 3.7 GeV/c internal experiments with the circulating beam (ANKE, COSY-11, EDDA) external experiments with the extracted beam (BIG KARL, TOF) CGSWHP'06 Ralf Engels 3
ANKE PIT at ANKE at COSY Magnets D2 spectrometer magnet D1, D3 beam bending magnets Technical constraints Detector systems Target Positive exchange & Negative within a Forward maintenance & Backward week Spectator Detectors New support bridge, following Targets the movement of D2 magnet Solid strip Magnetic shielding of components Cluster jet of the Atomic Beam Source (ABS) Polarized gas cell ( polarized gas jet ) ABS Storage cell Polarimeter 3D CAD drawing of PIT at ANKE Spectrometer ANKE CGSWHP'06 Ralf Engels 4
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 (HFS 1) P Z = -0.96 ± 0.01 (HFS 3) Lamb-Shift Polarimeter Storage cell in a test chamber ABS and LSP at the laboratory CGSWHP'06 Ralf Engels 5
ABS and LSP in the COSY hall December 2004 transfer to COSY hall (outside of the COSY tunnel) May 2005 tests after reassembling Platform for all electronic and supply components Heat exchanger with closed cooling-water circuit New support bridge Supports representing D1 and D2 June 2005 setup ready for installation at ANKE Setup in the COSY hall CGSWHP'06 Ralf Engels 6
PIT installation at ANKE Platform transportation ABS transportation CGSWHP'06 Ralf Engels 7
PIT at ANKE CGSWHP'06 Ralf Engels 8
Magnetic stray field of D2 40 26 300 90 150 135 30 25 55 30 33 55 200 550 300 x y z 6 15 30 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 CGSWHP'06 Ralf Engels 9
3. 0E- 07 2. 5E- 07 2. 0E- 07 1. 5E- 07 1. 0E- 07 5. 0E- 08 0. 0E+00 Test of the medium-field rf transition unit 3.0 Pressure in the target chamber, e-7 mbar. 2.5 2.0 1.5 1.0 0.5 0.0 0 200 400 600 800 1000 1200 1400 D2 current, A 0 T field strength in the D2 gap 1.58 T H beam OFF H beam ON, states 1 + 2 H beam ON, state 1 only CGSWHP'06 Ralf Engels 10
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 I D2 =563 A I D1D3 =1294.84 A B x B y B y B 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 ω L R=ω L /ω B ω B CGSWHP'06 Ralf Engels 11
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 mm 2 CGSWHP'06 Ralf Engels 12
Cooler stacking into the storage cell 28 stacks followed by 2s electron cooling after 58s acceleration tot p =600 MeV Cooler Stacking at COSY with ANKE is possible. Without storage cell with micropulsing to simulate the lower polarized source intensity, 2.5 10 10 were reached. CGSWHP'06 Ralf Engels 13
Results of the cell tests number of stored protons * 10 9 Θ ANKE injection type target injection after cooling flattop (600 MeV) 0º single injection no cell 83 21 14 single injection empty cell 7 5 3 80 stacking + electron cooling no cell 26 30 stacking + electron cooling empty cell 20 9.2º 30 stacking + electron cooling cell with H gas from ABS 9 6 CGSWHP'06 Ralf Engels 14
Storage cell and stochastically cooled beam Cooling off T p =831 MeV Cooling on CGSWHP'06 Ralf Engels 15
Use of the ABS jet Measured pressures in the target chamber, mbar Without catcher With catcher Without ABS jet 4.0 10-9 4.0 10-9 With ABS jet 3.0 10-7 3.7 10-8 Cosy beam ABS beam ABS-jet density, cm -3 integral thickness ~ 1.5. 10 11 cm -2 ~13cm ABS beam catcher CGSWHP'06 Ralf Engels 16
Summary of commissioning PIT transfer to COSY hall - December 2004 Cell test at ANKE - February 2005 PIT installation at ANKE - June 2005 PIT commissioning - Summer 05 Spring 06 Tests at ANKE with ABS and storage cell with stacking injection (Nov. 2005) and stochastic cooling (Mar. 2006) 1. Cell-target thickness for H (HFS 1 only) ~ 10 13 cm -2 2. Average luminosity for the storage-cell test ~ 10 29 cm -2 s -1 3. ABS jet-target thickness ~ 1.5. 10 11 cm -2 CGSWHP'06 Ralf Engels 17
Plans for the nearer future going on new cell production with Teflon coating Autumn 06 studies of nuclear polarization of molecules from recombined polarized H and D atoms ( use of the ABS in the ISTC project ) December 06 PIT reinstallation with Lamb-shift polarimeter at ANKE January 07 First experiment: pd (pp)n with STT Far future, parallel to ANKE measurements: Polarized Fusion with ABS and LSP! CGSWHP'06 Ralf Engels 18