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Shielding charged particle beams

Klaus Dehmelt 2019 Workshop on Polarized Sources, Targets, and Polarimetry Sep-23-2019. Shielding charged particle beams. why shielding charged particle beams. All EIC detector concepts based on solenoids. why shielding charged particle beams.

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Shielding charged particle beams

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  1. Klaus Dehmelt 2019 Workshop on Polarized Sources, Targets, and Polarimetry Sep-23-2019 Shielding charged particle beams

  2. why shielding charged particle beams All EIC detector concepts based on solenoids K. Dehmelt

  3. why shielding charged particle beams • Momentum measurement  charged final state particles’ curvature in magnetic field • , typically solenoid magnets • Forward measurements loose bending power • Solution: introduce , e.g., dipole magnet • Drawback:  beam deflection  beam depolarization • Shield charged particle beams K. Dehmelt

  4. shield charged particle beams • How to shield? • Compensate magnetic field lines in the region of interest • E.g., magnetic flux exclusion tube F. Martin et al., Nuclear Instruments and Methods Volume 103, Issue 3, 15 September 1972, Pages 503-514 K. Dehmelt

  5. shield charged particle beams • How to shield? • Compensate magnetic field lines in the region of interest • E.g., magnetic flux exclusion tube  superconducting • Distorts outside magnetic flux F. Martin et al., Nuclear Instruments and Methods Volume 103, Issue 3, 15 September 1972, Pages 503-514 K. Dehmelt

  6. shield charged particle beams • How to shield? • Ideal shield: ‘switch off’ magnetic interaction of magnetic material with existing magnetic fields without modifying them • Antimagnet: conceals magnetic response of volume under consideration without altering external magnetic fields  magnetic cloaking • Superconductors (SC) and isotropic magnetic materials K. Dehmelt

  7. concept magnetic field cloak SC Ferro-magnet magnetic cloak R1 R2 FedorGömöryet al.., Science 335, 1466 (2012),DOI: 10.1126/science.1218316 K. Dehmelt

  8. experimental realization Place cloak cylinder in magnetic field K. Dehmelt

  9. experimental realization manufacturing FM with customized mr dependent on fractional mass fm manufacturing SC with ReBCO “tape” K. Dehmelt

  10. experimental realization • Test setups with prototypes • Tandem Van de Graaf Facility (BNL)  shielding ion beams from magnetic dipole field • Helmholtz coil  measure permeability of FM cylinder + test cloaking at low magnetic fields • ANL-MRI up to 4 T  measure permeability of FM cylinder + test cloaking at magnetic fields up to 0.5 T K. Dehmelt

  11. experimental realization • Test setups with prototype constructions • 1 m long -- 2-layer HTS shield • 4.5 inches long -- 4-layer HTS shield • 4.5 inches long -- 45-layer HTS shield • 4.5 inches long -- 4-layer HTS cloak • 4.5 inches long -- 45-layer HTS cloak K. Dehmelt

  12. experimental realization • Test setups with prototype constructions • 1 m long -- 2-layer HTS shield Two double layer HTS wrapped around top/bottom of SS-tube K. Dehmelt

  13. experimental realization • Test setups with prototype constructions • 4.5 inches long -- 45-layer HTS shield Lamination: die-and-mandrel setup in oven K. Dehmelt

  14. experimental realization • Test setups with prototype constructions • 4.5 inches long -- 45-layer HTS cloak Manufactured FM shell and assembly around SC K. Dehmelt

  15. tandem van de graaf facility 1 m long -- 2-layer HTS shield  extends magnet K. Dehmelt

  16. tandem van de graaf facility • Structural imperfections + trapped background fields offset of 0.1 mT K. Dehmelt

  17. tandem van de graaf facility Beam ()deflection K. Dehmelt

  18. Helmholtz coil setup • High field stability – up to 50 mT K. Dehmelt

  19. Helmholtz coil setup • 4.5 inches long -- 4-/45-layer SC shield • Measurements along axis of shields K. Dehmelt

  20. Helmholtz coil setup • 4.5 inches long -- 4-layer SC shield/cloak(mr=2.43) K. Dehmelt

  21. Helmholtz coil setup • 4.5 inches long -- 4-layer SC shield/cloak(mr=2.43) K. Dehmelt

  22. Helmholtz coil setup • 4.5 inches long -- 4-/45-layer SC shield/cloak(mr=2.43) • 45-layer SC + cloak  imperfections K. Dehmelt

  23. anl-mri • Commercial MRI magnet, Bmax =4 T, operated up to 0.5 T • Hall probe table • Cloak box in LN2-bath K. Dehmelt

  24. anl-mri • 4.5 inches long -- 45-layer SC shield/cloak(mr=2.43) • mr effectively reduced due to higher fields K. Dehmelt

  25. anl-mri • 4.5 inches long -- 45-layer SC shield/cloak(mr=2.43) shield cloak K. Dehmelt

  26. conclusion • Demonstrated that BT can be cloaked up to 0.5 T • Promising device for shielding charged particle beams • Need to optimize manufacturing processes • Need careful study for optimal parameters • Reconsider SC at LHe temperature  extend to higher BT cloaking • Perform transformation optics and maybe use only room-temperature materials  meta-materials K. Dehmelt

  27. supporting slides • SC critical fields Bc1 / Bc2 : development of flux vortices  shielding time dependent v-d-G setup ANL-MRI K. Dehmelt

  28. supporting slides • Magnetic permeability (mr): influential factors Fill factor, empirical solution K. Dehmelt

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