The Polarized Internal Target at ANKE: First Results Kirill Grigoryev Institut für Kernphysik, Forschungszentrum Jülich PhD student from Petersburg Nuclear Physic Institute (PNPI), Gatchina, Russia Kyoto October 03, 2006

Kirill SPIN20062 COSY  COoler SYnchrotron internal experiments – with the circulating beam (ANKE, COSY-11, EDDA) external experiments – with the extracted beam (BIG KARL, TOF) with momenta up to 3.7 GeV/c ANKE at COSY Targets Solid strip Cluster jet Polarized gas cell ( polarized gas jet ) Magnets D2 – spectrometer magnet D1, D3 – beam bending magnets Detector systems Positive & Negative Forward & Backward Spectator Detectors Spectrometer ANKE p, p, d, d →

Kirill SPIN20063 Polarized Internal Gas Target Setup at the laboratory  Summer 2003 – Atomic Beam Source is ready for using in experiments PIT main components: ABS H or D H beam intensity (2 HFS) atoms/s Beam size at the IP σ = 2.85 ± 0.42 mm Polarization for hydrogen P Z = 0.89 ± 0.01 P Z =-0.96 ± 0.01 Lamb-Shift Polarimeter Target chamber with Storage Cell Setup at the COSY experimental hall  End of 2004 – Start of the PIT transportation to the COSY experimental hall ABS with infrastructure at the COSY experimental hall  Summer 2005 – After commissioning source is ready for installation at COSY Setup at ANKE at COSY  July 2005 – ABS is installed at the ANKE-experiment area at COSY Work only begins

Kirill SPIN20064 Magnetic Stray Field from D2 Magnet ABS with shielded components at ANKE

Kirill SPIN20065 Test of the Medium-field RF-Transition Unit No dependence of MFT on D2 field  Shielding ok

Kirill SPIN20066 PIT at ANKE Using of the ABS at ANKE jet target with storage cell An additional methods to improve COSY beam Electron coolingStacking at injection Stochastic coolingBeam scraping

Kirill SPIN20067 ABS-jet test with catcher Without ABS jet With ABS jet Without catcher 4.0· ·10 -7 With catcher 4.0· ·10 -8 ABS beam catcher ~13cm Measured pressures in the target chamber, mbar Number of events integral thickness ~ cm -2 ABS Beam COSY Beam

Kirill SPIN20068 Storage cell setup

Kirill SPIN20069 Cooler Stacking with the Storage Cell Θ ANKE beam Number of accelerated protons to 600 MeV no cellempty cellABS H–fed cell 0° electron cooling1.4x x10 9 Stacking + electron cooling 2.6x x °6.0x x stacks with 2s electron cooling acceleration to T p =600 MeV after 58s from cycle start Stored particles in the ring = 6.4 · 10 9 protons H target thickness = 2 · atoms/cm 2 Average luminosity > cm -2 s -1 &

Kirill SPIN Stochastic cooling Cooling off Cooling on T p =831 MeV Length of the cycle = 10 min Minimum energy for stochastic cooling is 831MeV

Kirill SPIN PIT commissioning Cell feeding with Nitrogen helps to obtain background from interactions with the cell wall Clear spot of the events from the cell-target gas pp→dπ + reaction

Kirill SPIN Target polarization from nuclear reaction Used HFS 1 and 2 (only MFT). WFT would provide higher polarization in state 3, but did not work. T p =831 MeV Assuming both polarization P + and P - were equal  P = 0.44±0.03 Theoretically we expect P + =0.85 and P - =-0.27(-0.18)  P = 0.56 (0.51) – HFS1 – HFS2

Kirill SPIN Future plans ongoing – Teflon coating and new cell production Autumn ’06 – studies of nuclear polarization of molecules from recombined polarized H and D atoms use of the ABS in the other project ( ISTC #1861 ) December ’06 – PIT reinstallation with Lamb-shift polarimeter at ANKE January ’07 – First double polarized experiment: dp → (pp)n →→ see talk D. Chiladze

Kirill SPIN Do we have zero field crossings along the ABS axis? 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 due to zero crossings Magnetic field along ABS axis I D2 = 563 A I D1D3 = A Magnetic field scan with ANKE at 5.3º using a 3D Hallprobe (Gatchina):