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CONSTRUCTION AND TEST OF A TRANSVERSE SUPERCONDUCTING HOLDING MAGNET

CONSTRUCTION AND TEST OF A TRANSVERSE SUPERCONDUCTING HOLDING MAGNET. 15th CB Meeting Mainz March 8th, 2010 Henry G. Ortega Spina. CONTENTS. Motivation Frozen Spin Mode Simulation Construction Tests & Results Conclusions & Outlook. MOTIVATION.

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CONSTRUCTION AND TEST OF A TRANSVERSE SUPERCONDUCTING HOLDING MAGNET

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  1. CONSTRUCTION AND TEST OF A TRANSVERSE SUPERCONDUCTING HOLDING MAGNET 15th CB Meeting Mainz March 8th, 2010 Henry G. Ortega Spina

  2. CONTENTS • Motivation • Frozen Spin Mode • Simulation • Construction • Tests & Results • Conclusions & Outlook Henry G. Ortega Spina A2-Collaboration

  3. MOTIVATION • Spin polarized targets needed to complete nuclear physics experiments, in particular to study internal structure of nucleons in detail. • Information about polarization observables inferred from differential cross section of photoproduction. Henry G. Ortega Spina A2-Collaboration

  4. lin lin circ g Beam P P P g g g unpol æ p ö æ p p ö + - ç ÷ ç ÷ Target 0 , , è 2 ø è 4 4 ø æ ö s d S ç ÷ P - - unpol W è d ø P - - H F x P T P - - y P - - G E z Photoproduction of pseudoscalar meson with polarized beam and target Target Beam Henry G. Ortega Spina A2-Collaboration

  5. MOTIVATION MOTIVATION MOTIVATION MOTIVATION • “Internal” superconducting holding magnets for longitudinally and transversally polarized targets. • Design and construct an “internal” superconducting holding coil for transverse polarization. Henry G. Ortega Spina A2-Collaboration

  6. FROZEN SPIN MODE • Frozen Spin Target scheme: cooling down, high magnetic field and optical pumping. • Spins direction chosen beforehand with holding magnets. • “External” holding magnets are very large and provide strong fringe field. • First “internal” holding coil discussed in 1980 (Niinikoski, 1980) and developed in 1992 (Dutz et al., 1995). Henry G. Ortega Spina A2-Collaboration

  7. The Mainz Frozen Spin Target Copper: T=300K  70K HTS: T=70K  4K NbTi: T=4K  1.5K Henry G. Ortega Spina A2-Collaboration

  8. Magnet Microwave system NMR system Henry G. Ortega Spina A2-Collaboration

  9. SIMULATION • “Racetrack” coil: magnetic field highly non-uniform and not appropriated for a cylinder. • “Saddle” coil: winding must fit to the so-called overlapping ellipse or “cosine” shape of current distribution. Henry G. Ortega Spina A2-Collaboration

  10. SIMULATION SIMULATION SIMULATION Ideal case for dipole magnet: 4-layer dipole: N1=N2=138 N3=N4=78 Henry G. Ortega Spina A2-Collaboration

  11. SIMULATION SIMULATION SIMULATION By (G) vs. X (cm) By (G) vs. Y (cm) Henry G. Ortega Spina A2-Collaboration

  12. SIMULATION Henry G. Ortega Spina A2-Collaboration

  13. SIMULATION Henry G. Ortega Spina A2-Collaboration

  14. SIMULATION SIMULATION SIMULATION Henry G. Ortega Spina A2-Collaboration

  15. CONSTRUCTION • Copper/scandium wire with 54 Nb-Ti filaments embedded in it. • Cu:Sc=1.35:1 • Alloy composition: Nb47wt.%Ti • Diameter=0.222mm • It achieves currents up to 50A at 4.2K and 1T. Henry G. Ortega Spina A2-Collaboration

  16. CONSTRUCTION CONSTRUCTION 10cm 17cm Henry G. Ortega Spina A2-Collaboration

  17. Henry G. Ortega Spina A2-Collaboration

  18. Copper holder Insert Cryogenic Hall generator Henry G. Ortega Spina A2-Collaboration

  19. TESTS & RESULTS TESTS & RESULTS • First test in a helium dewar and magnetic field in the centre of the target region. • Field homogeneity could not be analyzed. • Different currents applied and Hall voltage measured with the probe. Henry G. Ortega Spina A2-Collaboration

  20. TESTS & RESULTS TESTS & RESULTS Magnetic field obtained from the Hall voltage (black) with a mean loaded sensitivity of 0.95 mV/kG. Henry G. Ortega Spina A2-Collaboration

  21. TESTS & RESULTS TESTS & RESULTS Henry G. Ortega Spina A2-Collaboration

  22. TESTS & RESULTS TESTS & RESULTS TESTS & RESULTS • Transverse holding coil implemented within the Mainz FST and tested under beam conditions in December (2009) and February (2010). • Stable temperature around 30mK and holding field corresponding to 30A (~0.4T) at 1.5K. • Butanol target polarization greater than 80% and relaxation time of 1000 hours. Henry G. Ortega Spina A2-Collaboration

  23. TESTS & RESULTS TESTS & RESULTS Henry G. Ortega Spina A2-Collaboration

  24. Holding field Positive DNP Negative DNP Henry G. Ortega Spina A2-Collaboration

  25. CONCLUSIONS & OUTLOOK • After many attempts a transverse holding dipole magnet has successfully been constructed. • Magnetic field was measured in the centre of the target cell region. The obtained values were very close to those given by the computer simulation. • The transverse holding coil was implemented in the cryostat of the Mainz FST and satisfactory tested observing no quenches or polarization loss. • New measurements with transverse polarization throughout this year and data analysis in a near future. Henry G. Ortega Spina A2-Collaboration

  26. Jen ĉio!Koran dankon por via atento! Speciala danko al Oleksandr Kostikov

  27. GAUSSMETER GAUSSMETER Lake Shore cryogenic Hall generator HGCA-3020 Operating temperature range: 4.2K-375K Diameter: 6.35mm Active area: 0.8mm Henry G. Ortega Spina A2-Collaboration

  28. ELLIPSE GAP WIDTH Henry G. Ortega Spina A2-Collaboration

  29. FROZEN SPIN MODE FROZEN SPIN MODE • Energy levels of particles with spin are splitted in the presence of an external magnetic field. • Spin polarization is the asymmetry in the populations of the levels. Henry G. Ortega Spina A2-Collaboration

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