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Future activities of the COMPASS polarized target

Learn about the latest developments and upgrades in the COMPASS experiment at Bochum University, including polarized target technology and future activities. Explore topics such as muon and hadron programs, gluon polarization measurement, and open charm lepto-production. Discover the significance of the polarized target materials, magnetic fields, and dynamic nuclear polarization techniques for high-quality data collection. Stay informed about the ongoing beam upgrades and system enhancements for increased statistical accuracy. Exciting breakthroughs await in the field of physics research.

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Future activities of the COMPASS polarized target

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  1. Future activitiesof the COMPASS polarized target N. Doshita University of Bochum, Germany

  2. Contents ・The COMPASS experiment ・The Polarized Target 2002-2004 ・Upgrade for 2006 ~ ・Summary

  3. CERN and COMPASS

  4. The COMPASS experiment Physics data taking started in 2002 • Muon program -Nucleon spin structure --- gluon contribution -Polarized muon beam and polarized nucleon target • Hadron program -Meson spectroscopy -Hadron beam and hydrogen, carbon target

  5. Gluon polarization measurement in the COMPASS Experimentally measurable double spin cross section asymmetry via PGF PB: Beam polarization PT: Target polarization f: Dilution factor N : Number of events : Direction of beam polarization Dilution factor : polarizable nucleon rate in material  : Direction of target polarization Aphys  Gluon polarization (double spin asymmetry) Extraction What kinds of events can be approached to realize PGF ? • Open charm production events • High-PT hadron production events D0, D0* Low statistics

  6. exp A d 1 = exp A f phys 2N P P A B T Requirement of Polarized Target Statistical accuracy -High polarization -High dilution factor -Large target COMPASS polarized target • - Target material 6LiD (high dilution factor), 350g • - Magnetic field 2.5T superconducting magnet • Temperature 60mK and 300mW at 300mK • by dilution refrigerator  Dynamic Nuclear Polarization with Microwave Deuteron polarization more than 50 %

  7. COMPASS polarized target2002 ~ 2004 Still pumping line Magnet: 2.5 T solenoid 0.5 T dipole 3He precooling line µ beam 69 mrad Twin target cells 60 cm + 60 cm Mixing chamber : 6 L

  8. Dilution refrigerator 3He Pumping line Magnet Beam

  9. Upgrade for 2006 ~

  10. 180 mrad Upgrade part 1 Large acceptance - F ~60cm - 30% gain in statistics 2.5T Solenoid, 0.5T Dipole - Solenoid: < 100 ppm homogeneity - ~25 L/hour Liq. He

  11. Upgrade part 2 3 target cells To reduce false asymmetry Large cavity Fit on new magnet talk of Y. Kisselev

  12. Upgraded PT system for 2006 Ready in next spring Data taking: June 14th ~

  13. COMPASS Oxford Danfysik magnet • OD magnet assembly was finished at December 2004 and has been tested in Saclay. • It is almost finished to test the magnet and construct its instruments. • The magnet is being delivered to CERN in the end of this month.

  14. COMPASS OD magnet 1st attempt to get uniform field (June 24th): obtained less than 100 ppm homogeneity now 100 ppm Request is ≤ 100 ppm Target region 130cm

  15. Summary - The COMPASS polarized target has been used since 2002. - The system is upgraded for 2006 ~. - 3 target cells - New large acceptance magnet - New microwave cavity - Expect high statistics and high quality data in 2006

  16. Open charm lepto-production via photo-gluon fusion C D0K- + p+ D0K+ + p- ー C

  17. Upstream Downstream Muon (a) (b) (c) (a) (c) Field Rotation (b) In order to cancel the systematic error • Spectrometer acceptance • Time dependence variation Target material spin direction 33 minutes every 8 hours

  18. Figure of Merit r : density k : packing factor f ‘: effective dilution factor PT : polarization The beam time needed to achieve a certain statistical accuracy is inversely proportional to the FoM. FoM = rk(f ‘PT)2 For the extraction of the real physics Bjorken-x-dependence of dilution factor should be considered.

  19. Electron fast relaxation Electron fast relaxation Electron fast relaxation Electron fast relaxation Dynamic nuclear polarization Paramagnetic centers are needed Spin status Dipolar-dipolar interaction Polarization @2.5T and 0.3K Electron: 99.9% Deuteron: 0.17% Transfer the high electron polarization to deuteron polarization

  20. COMPASS dilution refrigerator 15-20 L/h 3He of 1400 L NTP 4He of 9200 L NTP 3He flow 30-100 mmol/sec 2000 L 13500 m3/h

  21. microwave guide target material microwave stopper microwave cavity 70 mm 1600 mm mixing chamber upstream downstream Calibrated sensors Non-calibrated sensors TTH4: RuO TTH7: speer 220 ohm TTH1: speer 220 ohm TTH6: RuO TTH2: speer 220 ohm Mixing chamber Beam  30mm 600 mm

  22. Microwave system 0.2W needed for both cells Microwave cavity Microwave stopper holes Mixing Chamber 2W due to long waveguide Power control attenuators Power supply Microwave generator 10W output power

  23. NMR System 10 coils can be measured at the same time. NMR coil UT-85 Cable Cu jacket semi-rigid material 6LiD Yale card Liverpool Q-meter PTS 250 Microwave generator scope VME-bus 10 ch ADC 12 bit DC offset subtraction 16 ch ADC 16 bit Splitter ADC/DAC 12 bit 96 ch digital I/O frequency control trigger signal gain selection signal bus extender VME-MXI PC in the control room Windows 2000 data acquisition program (LabVIEW) data storage NI MXI-2 cable

  24. Average polarization in the whole physics runs in 2003 Red : Upstream Green : Downstream

  25. Ethernet module PC CPU PLC (programmable logic controller) System Siemens S7-300, CPU315-2DP with 48 kByte memory intranet Control room • Pressures • Flow rates • Gate valve control • Needle valves control • Interlock (still heater, MW) Touch panel Profibus Pump room Beam area • LN2 trap level control • 4He roots pump • 3He pumps • Cooling water security • room temperature • Air conditioning • Isolation vacuum • LHe valve • Turbo pump control • Diffusion pump • Vertical, horizontal screens Power : 48V UPS, 49 channels are used

  26. Cooling power MC Temperature [mK] 0% DNP 50% Frozen mode 3He flow rate [mmol/sec]

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