S. Stahl: Cryogenic Electronics in Ion Traps Part I
Cryogenic Electronics in Ion Traps
S. Stahl, CEO Stahl-Electronics
S. Stahl: Cryogenic Electronics in Ion Traps Part I
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
S. Stahl: Cryogenic Electronics in Ion Traps Part I
Part I
Principles of Ion Traps
1.
2.
3.
4.
Penning Trap
Paul Trap
Kingdon Trap
Trap Applications in Science and Industry
S. Stahl: Cryogenic Electronics in Ion Traps Part I
1. Penning Trap
Charged Particle
Mass m, Charge q
 Lorentz-force: radial confinement
free cyclotron motion:
 Electrostatic potential: axial confinement
 leads to axial oscillation
q
 c  Bz
m
S. Stahl: Cryogenic Electronics in Ion Traps Part I
Implementation: Hyperbolical Trap
Magnetic field
=>Advantage: harmonic motion
(frequency independent of energy)
S. Stahl: Cryogenic Electronics in Ion Traps Part I
Resulting ion motion
3 degrees of freedom:
axial motion:
oscilla
tioninE-field
Axial
Motion
z 
qV0
~1MHz
md2
Energy: 0 ... eV ... keV
Reduced Cyclotron Motion



c
z
c




~10MHz

2 4 2
2
2
Problem Magnetron-Motion:
Inherently unstable



c
z
c




Magnetron Drift 
2 4 2 ~10kHz
2
2
S. Stahl: Cryogenic Electronics in Ion Traps Part I
Manipulation of Motions
- Excitation:
electric dipole ac fields increase amplitude / radii
=> applying z, +, - 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 (+ + -, z + -), or phase-defined („Magnetron Cooling“)
Rotating Wall (large ion numbers)
Lit: Werth, Gheorghe, Major : Charged Particle Traps, published by Springer
S. Stahl: Cryogenic Electronics in Ion Traps Part I
Dipole excitation:
electric dipole field in z or r-direction
S. Stahl: Cryogenic Electronics in Ion Traps Part I
Quadrupole excitation:
electric quadrupole field in r-z direction or radial plane
S. Stahl: Cryogenic Electronics in Ion Traps Part I
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
S. Stahl: Cryogenic Electronics in Ion Traps Part I
Typical Penning Trap Parameters
B0 = 0.1 T .... 6T (typical in science) ... 20T
(heavier particles -> high fields required)
U0 = 2V .. 200V
(low voltages: patch effect problems)
Stored particles:
from lightest
electrons/positrons,
to heaviest
organic molecules
(e.g. m = 10‘000u)
storage times
normal-conducting
1sec ....
1 year (cryogenic systems) (water-cooled)
number of particles:
one to several millions
superconducting
permanent
(up to 2T)
S. Stahl: Cryogenic Electronics in Ion Traps Part I
Penning Trap Variants
- classical hyperpolical electrodes
B-field
- cubic type trap (chemistry)
- 3pole-Brown-Gabrielse-type trap
Laser, Microwaves, Ions,...
A. Marshall et al.
Rev. Mass. Spec. 17, 1 (1998).
L.S. Brown, G. Gabrielse,
Rev. Mod. Phys. 58, 233 (1986).
S. Stahl: Cryogenic Electronics in Ion Traps Part I
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)
S. Stahl: Cryogenic Electronics in Ion Traps Part I
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
S. Stahl: Cryogenic Electronics in Ion Traps Part I
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)
S. Stahl: Cryogenic Electronics in Ion Traps Part I
Planar Trap:
Easy Access for Photons and Scalability
Open structure allows
easy access with Lasers,
Microwaves etc.
“100 traps on 1 Euro“
Interesting for Quantum Computing, for Mass Analysis, etc.
S. Stahl: Cryogenic Electronics in Ion Traps Part I
Planar Traps: Implementation approaches
• Multiple ring electrode structures
• multi-layer PCB
• on board filters
• easy fabrication
• structures > 100..150 µm
Schmidt-Kaler et al.
QUELE-Project
S. Stahl: Cryogenic Electronics in Ion Traps Part I
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)
S. Stahl: Cryogenic Electronics in Ion Traps Part I
Paul Traps: Many different shapes exist
simple ring
(ground around is second electrode)
hyperbolic shape
Paul-Straubel-Type
Trapped particles
Quadrupolar Rods
S. Stahl: Cryogenic Electronics in Ion Traps Part I
3. Kingdon Trap
Kingdon Trap
modern variant: Orbitrap
Pure Electrostatic Trap
=> no (expensive) magnet needed
Advantage: very simple
Disadvantage: Short Storage Times
Improved version,
Longer Storage time
Important tool in analytical
mass spectrometry
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
S. Stahl: Cryogenic Electronics in Ion Traps Part I
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
S. Stahl: Cryogenic Electronics in Ion Traps Part I
Mass Measurements in Penning Traps
Atomic
Physics
Nuclear
Physics
nuclear binding energies,
Q-values
e- binding energy
QED test
m/m  1·10-7
Nuclear
Structure
shell closure, pairing,
deformation, halos,
isomers
m/m  1·10-10
trap assisted
decay
spectroscopý
m/m  1·10-7
trap assisted
laser
spectroscopý
exotic
systems
Weighing
Weak
Interaction
symmetry tests,
CVC hypothesis
m/m < 3·10-8
Courtesy Klaus Blaum
Astrophysics
Fundamental
Properties
tests of nuclear models
and formulae
nuclear synthesis,
r- and rp-process m/m < 1·10-7
m/m  1·10-7
S. Stahl: Cryogenic Electronics in Ion Traps Part I
- End of part I -
S. Stahl: Cryogenic Electronics in Ion Traps Part I
Thanks for your attention
S. Stahl: Cryogenic Electronics in Ion Traps Part I
g-factor setup Mainz:
vertical 4Kdewar setup
(g-factor, Mainz)
4K-electronics section
4K-axial
amplifier
g-factor trap
4K-broadband
FT-ICR amplifier
( Mainz 2004 )