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Electrostatic deflector development

Electrostatic deflector development. 28.03.2019 I Kirill Grigoryev on behalf of the JEDI collaboration. Outline. Electric Dipole Moment Storage rings for EDM measurement Laboratory tests with small prototypes Large deflectors development Conclusion and outlook. -q. +q. p. -. +. d.

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Electrostatic deflector development

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  1. Electrostatic deflector development 28.03.2019 I Kirill Grigoryev on behalf of the JEDI collaboration

  2. Outline Electric Dipole Moment Storage rings for EDM measurement Laboratory tests with small prototypes Large deflectors development Conclusion and outlook

  3. -q +q p - + d Electric Dipole Moment Definition : p = d · q Example : permanent EDM of H2O molecule p ~ 6 · 10-30 C·m ~ 4 · 10-9 e·cm

  4. no EDM (d = 0) Charge symmetricNOT Charge symmetric d aligned with spin EDMs: Discrete Symmetries Permanent EDMs violate P and T symmetry Assuming CPT to hold - CP violated also

  5. General case The spin motion for relativistic particles in electromagnetic fields is determined by the Thomas-BMT equation Ω : angular precession frequency d : electric dipole moment G : anomalous magnetic moment γ : Lorentz factor Ideal case Inject particles with spin pointing towards momentum direction „Frozen Spin“: without EDM spin stays aligned to momentum EDM couples to electric bending fields Slow buildup of EDM related vertical polarization Large electric fields (E = 17 MV/m at 2cm for 30m radius ring)

  6. COoler SYnchrotron ring for (polarized) protons and deuterons EDM measurements at Jülich Magnetic ring Electromagnetic ring Electric ring existing proposed future … an ideal starting point for precursor experiment Cyclotron

  7. 20mm Atmosphere 10-2 mbar 10-9 mbar -> 10-2 mbar -> 10-9 mbar -> 10-12 mbar Scroll fore pump Turbo-molecular pump Ion getter pump Test stand for small electrodes Electrodes in the vacuum chamber

  8. Test electrodes roughness Stainless steel Aluminum Material Stainless steel Aluminum Treatment Cleaning Polishing TiN coating Spacing between electrodes variable from 0.1 to 500 mm High Voltage up to 30 kV uncoated Average = 0.10 μm Maximum = 1.17 μm Average = 0.18 μm Maximum = 1.11 μm TiN coated Average = 0.10 μm Maximum = 2.54 μm Average = 0.08 μm Maximum = 1.78 μm

  9. Measurement results Uncoated stainless steel Coated Aluminum arXiv: 1812.07954

  10. 1400 mm 2700 mm Foil tighteners and actuators Deflectors HV - feed-thorough Necessary parts Parameters 2900 mm Electrode length = 1020 mmElectrode height = 90 mmElectrode spacing = 20 – 120 mmMax. electric field = ±200 kV on eachMaterial / coating = TiN coated Aluminum Deflector support Power supplies (200kV) Chamber protection foil Test deflectors Large deflector tests

  11. + - + - By Electron trajectories simulation Electrons initial energy: 50 eV Voltage: ±100 kV → 4MV/m B-field: 0.15 T B-field: 0 T

  12. Conclusion and outlook Achievements Small electrodes - Stainless Steel vs. TiN aluminum electrodes tests - Roughness measurements Large electrodes - Preparation for installation is almost finished Plans Small electrodes - Test all possible combinations of materials and coatings - Try gas conditioning and measure roughness again Large electrodes - Installation into vacuum chamber (indium sealing) - Mechanical and electrical tests - High voltage tests

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