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Institut für Kernphysik

Institut für Kernphysik. Frozen Spin Target. 1.- Polarised Target Operation 2.- Short Term Plans 3.- Modifications 4.- Long term plans . 17 th Crystal Ball Meeting Mainz, February 28th, 2011 Andreas Thomas. Operation. Cryostat. Movable Crystal Ball 4 p - Photon Detector.

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Institut für Kernphysik

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  1. Institut für Kernphysik Frozen Spin Target 1.- Polarised Target Operation 2.- Short Term Plans 3.- Modifications 4.- Long term plans 17th Crystal Ball Meeting Mainz, February 28th, 2011 Andreas Thomas

  2. Operation Cryostat Movable Crystal Ball 4p- Photon Detector Movable 5Tesla Polarising Magnet First Beam with Transverse Polarisation started 15th December 2009. In 2010 we had more than 2000 hours beam on this target.

  3. Cryostat Performance T=24mK T=27mK T=29mK Dt=40h Temperature stability: DT ~ +- 0.2mKelvin (one day) (typical one week measurement period).

  4. Frozen Spin Target  Relaxationtime 26 mK, 0.44T Relaxation time of butanol at 60 mK depending on the applied magnetic field

  5. Target material CH3 CH3 CH3 CH3 N O Saturated electrons of target material not polarized (Pauli principle) Radicals in material by chemical or radiative doping Free electrons Dilution factor (fButanol=10/74) determines quality of target material. We have 9*1022 pol. Protons per cm2 in our 2cm long target cell. 2cm Butanol Tempo

  6. 30mm C4H10O – 60% Vacuum 3He/4He – 6% Filling factor ~ 60%  H. Ortega Spina

  7. Degree of Polarisation Soldering of the NMR coil (target material has to be kept under liq. Nitrogen) and installation into the cryostat. X-ray picture with Beamspot and NMR coil from last week.

  8. NMR System for Polarisation measurement B=0T B=2.5T

  9. Typical NMR Signals Enhanced Signal at 70% Polarisation after spin rotation Thermal Equilibrium-Signal 0.5% Polarisation 2.5Tesla,1Kelvin

  10. Temperature measurement AVS Picowatt Resistance Bridge ! Systematic error for all asymmetries!

  11. Target material • Density and species of the radicals • are very important for: • maximum degree of polarization • polarization build up times • relaxation times • Trityl-Radikal D-Butanol [Gerhard Reicherz, PT Ruhr-Universität Bochum, Next talk] Highest Deuteron polarisation due to new doping material with narrow ESR from Bochum.

  12. Deuteron NMR Signals

  13. Short term plans • Proposal: • Beam for 3 weeks in April (proton target optimized for ph and h) • Beam for 2 weeks in May (deuteron target broad band at 1557MeV) • Dismounting Cryostat after final test (TE-calibration, filling factor…) • Mounting of EPTagger. • Mounting of liquid hydrogen target (cell length 3cm or 5cm or 10cm?). • Test beamtime end of summer/fall.

  14. Modifications: Magnet Technology DNP at 200mK and 2.5T with 70GHz microwaves. Frozen spin target (25mKelvin, 0.6T). Secondary particles punch through holding coil. All directions of polarization. Transverse (Saddle coil) and Longitudinal (Solenoid) Internal Holding Field (1.2K, 0.6T)

  15. High Field 1T Threshold Production Transverse Field

  16. Modifications: Internal PolarisingCoil Problem is the required field homogeniety of 10-E4. Notched solenoid. 3d finite element calculation, optimisation and precise production needed. DNP at 200mK and 2.5T with 70GHz microwaves. 10Layer coil at 50A. Secondary particles punch through holding coil. Higher momentum threshold.

  17. New Coil with 10 layer (2.5Tesla) in Mainz mechanical workshop.

  18. Modifications: ActivePolarised Target Vacuum 3He/4He – 6%  Talk S.Schrauf

  19. Long term plans • Change from transverse to longitudinal polarisation. • Internal polarising coil for high luminosity and precission experiments. • Active polarised target for treshhold experiments.

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