S. Stahl, CEO Stahl-Electronics

1. Cryogenic Electronics in Ion Traps S. Stahl, CEO Stahl-Electronics

2. Outline I. Principles of Ion Traps 1. Penning Traps 2. Paul Traps 3. Kingdon Trap 4. Trap Applications in Science and Industry II. Cryogenic Traps 1. Why Cryogenic ? 2. Precision Measurements in Traps 2.1 Magnetic Moments 2.2 Mass Measurements 2.3 Fundamental Constants III. Non-destructive Particle Detection 1. Why non-destructive detection? 2. How does it work? 3. Sensitivity improvement 4. Resistive Cooling 5. Detection of cold particles IV. Design of Cold Amplifiers 1. Which Semiconductors are suitable? 2. Typical Amplifier Design for Ion Traps 3. Anchoring and Cabling 4. Implemention Examples V. Other Components : Filters, Switches

3. Part I • Principles of Ion Traps • Penning Trap • Paul Trap • Kingdon Trap • Trap Applications in Science and Industry

4. Lorentz-force: radial confinement free cyclotron motion: • Electrostatic potential: axial confinement • leads to axial oscillation 1. Penning Trap Charged Particle Mass m, Charge q

5. Magnetic field Implementation: Hyperbolical Trap =>Advantage: harmonic motion (frequency independent of energy)

6. Axial Motion ~1MHz Reduced Cyclotron Motion ~10MHz Magnetron Drift ~10kHz Resulting ion motion 3 degrees of freedom: Energy: 0 ... eV ... keV Problem Magnetron-Motion: Inherently unstable

7. Manipulation of Motions • Excitation: • electric dipole ac fields increase amplitude / radii • => applying wz, w+, w- radio frequency field • => heating until loss of particles • Cooling: • Laser cooling, if optical transition exists ( < Millikelvin) • Resistive Cooling ( ~ few Kelvin) • Sympathetic Cooling (~ few Kelvin to Millikelvin) • Magnetron Centering • Motional Sidebands (w+ + w-, wz + w-), or phase-defined w- • („Magnetron Cooling“) • Rotating Wall (large ion numbers) Lit: Werth, Gheorghe, Major : Charged Particle Traps, published by Springer

8. Dipole excitation: electric dipole field in z or r-direction

9. Quadrupole excitation: electric quadrupole field in r-z direction or radial plane

10. Rotating Wall drive: A B 90° degrees phase shifted sine signals D C => rotating electric wall in radial plane centers particles (applies rather for multiparticle/plasma regime) Lit.: X.-P. Huang, F. Anderegg, et al., Phys. Rev. Lett. 78, 875 (1997) S. Bharadia, M. Vogel, D.M. Segal, R.C. Thompson, Dynamics of laser-cooled Ca+ ions in a Penning trap with a rotating wall; submitted to Applied Physics B

11. Typical Penning Trap Parameters B0 = 0.1 T .... 6T (typical in science) ... 20T U0 = 2V .. 200V Stored particles: from lightest electrons/positrons, to heaviest organic molecules (e.g. m = 10‘000u) storage times 1sec .... 1 year (cryogenic systems) number of particles: one to several millions (heavier particles -> high fields required) (low voltages: patch effect problems) Magnets superconducting normal-conducting (water-cooled) permanent (up to 2T)

12. A. Marshall et al. Rev. Mass. Spec. 17, 1 (1998). - cubic type trap (chemistry) - 3pole-Brown-Gabrielse-type trap L.S. Brown, G. Gabrielse, Rev. Mod. Phys. 58, 233 (1986). Laser, Microwaves, Ions,... Penning Trap Variants - classical hyperpolical electrodes B-field

13. Penning Trap: Some Real-world designs Precision trap for single-ion mass analysis (GSI / Univ. Mainz, Triga) Precision trap for single-ion g-factor determinations (Univ. Mainz) „Shiptrap“ for mass analysis of short-lived isotopes (GSI)

14. Example Open Endcap Structure: KATRIN-Trap (commissioning 2009..2011) n-Experiment KATRIN, Karlsruhe • large trap (72mm diam.), open structure • operated at T = 77K • „non-precision“ trap

15. Planar Trap Marzoli et al. Experimental and theoretical challenges for the trapped electron quantum computer J. Phys. B: At. Mol. Opt. Phys. 42 (2009) 154010 (11pp) Goldman and Gabrielse: Optimized planar Penning traps for quantum-information studies Phys. Rev. A 81, 052335 (2010)

16. “100 traps on 1 Euro“ Planar Trap: Easy Access for Photons and Scalability Open structure allows easy access with Lasers, Microwaves etc. Interesting for Quantum Computing, for Mass Analysis, etc.

17. Planar Traps: Implementation approaches Schmidt-Kaler et al. • Multiple ring electrode structures • multi-layer PCB • on board filters • easy fabrication • structures > 100..150 µm QUELE-Project

18. 2. Paul Traps / Quadrupole Ion Traps metallic electrodes Resulting macromotion in a pseudo potential of a few eV => 3D confinement • No magnetic field needed • high (1kV) AC fields needed • problem RF-heating => cooling technique needed • (like: buffer gas cooling, strong laser cooling)

19. Paul Traps: Many different shapes exist Paul-Straubel-Type simple ring (ground around is second electrode) Trapped particles Quadrupolar Rods hyperbolic shape

20. Kingdon Trap modern variant: Orbitrap Pure Electrostatic Trap => no (expensive) magnet needed 3. Kingdon Trap Improved version, Longer Storage time Important tool in analytical mass spectrometry Advantage: very simple Disadvantage: Short Storage Times Lit: Blümel, R (1995). "Dynamic Kingdon trap". Physical Review A 51 (1): R30–R33. doi:10.1103/PhysRevA.51.R30 Hu, Noll, Li, Makarov, Hardman, Graham Cooks R (2005): "The Orbitrap: a new mass spectrometer". Journal of mass spectrometry : JMS 40 (4): 430–43. doi:10.1002/jms.856

21. 4. Trap Applications in Science and Industry • Industry: • Mass Analysis in Chemistry, Biology, Environmental Analytics • Paul Traps / Mass Filters • Penning Traps • (specially FT-ICR-Traps) • Science / Fundamental Research: • Paul Traps • Quantum Optics, Frequency Standards, Atomic Physics, ... • Penning Traps • Fundamental constants, Laser-spectroscopy, g-factor • mass references and..... Lit: Werth, Gheorghe, Major : Charged Particle Traps, published by Springer

22. Mass Measurements in Penning Traps Courtesy Klaus Blaum

23. - End of part I -

24. Thanks for your attention

25. g-factor setup Mainz: vertical 4K- dewar setup (g-factor, Mainz) 4K-electronics section 4K-axial amplifier g-factor trap 4K-broadband FT-ICR amplifier ( Mainz 2004 )