The André E. Lalonde
Accelerator Mass Spectrometry Lab
at the University of Ottawa
Liam Kieser, Ian Clark, Jack Cornett and Xiaolei Zhao, University of Ottawa
Ted Litherland, University of Toronto
Instrumentation Session, CAP 2014 Congress,
Laurentian University, June 17
A. E. Lalonde AMS Lab
Overview
1.
Introduction – What is AMS?
a) Basic Description – Advantages, Applications, Challenges
b) Lab Photo Tour – Principal Components
c) Critical Component – the ion source
2. Design Goals for the Lalonde Lab
a) Earth and Planetary Sciences
b) Bio-medical and Pharmaceutical Sciences
c) Anthropological and Cultural Sciences
d) AMS Research and Innovation
3. Advances in AMS Technology
a) Negative Ion Chemistry in the Ion Source
b) Ion-Gas Reactions and Isobar Separation
4. The New Facility at uOttawa - Summary
Accelerator Mass Spectrometry (AMS)
A synthesis of:
Conventional mass spectrometry, and
Particle accelerator technology -- usually a tandem
electrostatic accelerator
Advantages:
Filter or Analyzer
Heavier Ions
■ Molecular interference free measurements
Ion Source
(Molecules destroyed in the charge changing process)
■ Measurements with extremely low dark current
Lighter
Ionsof MeV provide single
(High energy -- 100s of keV
to 10s
Ions
atom counting capability and some degree of atom
identification)
Sample
Detector
■ Atomic isobar elimination is special cases
14C (14N), 26 Al (26Mg), 129I (129Xe), 202Pb (202Hg)
Accelerator Mass Spectrometry (ctd)
Applications:
• Concentration or isotope ratio measurements for long-lived
radio-isotopes or rare atoms for dating or tracing
e.g. 3H, 10Be, 14C, 26Al, 36Cl, 41Ca, Ag, 129I, Pt group, actinides
•
•
Levels ranging from 1 part in 1010 to 1 part in 1016
Used in Archaeometry, Astrophysics, Biology, Bio-medical
research and clinical practice, Earth, Environmental and
Planetary science, Materials research, Pharmacology
Challenges:
• Need to make negative ions of the analyte
(Tandem accelerator operation)
• Some sample materials require extensive, labour-intensive
preparation e.g. 10Be, 14C
• Atomic isobars can be difficult to eliminate
(except in the special cases)
Accelerator Mass Spectrometry (ctd)
AMS System Schematic:
High Energy
Mass Spectrometry
Low Energy Mass
Spectrometry
Gas Ionization
Detector for
rare species
Negative Ion
Source
Sample
Electric
Analyzer
3 MV Power Supply
Electric Analyzer
Faraday Cups for
abundant species
Magnetic
Analyzer
Gas-Filled Electron
Stripper Canal
Tandem Accelerator
Magnetic
Analyzer
Accelerator Mass Spectrometry (ctd)
AMS System: View from Low Energy End
Accelerator Mass Spectrometry (ctd)
AMS System: View from above the High Energy End
The Ion Source
Requirements:
Head
-28kV
► Produce negative ions from a wideSource
range
of Base
elements
Caesium Ionizer
► Large ion current (at least 10s of μA, 100s good if possible)
to obtain sufficient counting statistics for low concentration
of rare species with a large ratio to abundant species
Sample (Target)
► Stable-35operation
for a variety of sample matrices
kV
►
Relatively low memory of previously analysed samples
Extraction Cone
→ Development of the negative ion caesium sputter source in the
(ground potential)
1970s made AMS possible
Caesium Vapour feed
Ion Source
HVE SO-110 200 sample, solid/gas ion source
Electric Analyser
Sample
Carousel
Source Head
Ion Source:
Source Head Flange
In Place
On Maintenance Stand
Target
Cooling
Lines
Caesium
Vapour
Feed
Target holder
Caesium
Ionizer
Target holder -35 kV
Source head base / support
-28 kV
Ion Source:
Target Wheel
– capacity: 200 targets in
4 circles of 50
– access time to neighbouring target: ~2 seconds
Ion Source:
Target Assembly
For solid materials
– compress into a 1.3 mm Φ
pellet in a replaceable Al
or SS cylinder
For gases
– provides the microenvironment for the
conversion of CO2 into
negative carbon ions
– one assembly must be
prepared for each 14C
measurement
A. E. Lalonde AMS Lab Design Goals
For Earth and Planetary Sciences:
- as wide a range of elements and isotopes as possible – from 3H to 244Pu
- a full complement of ancillary equipment and sample preparation techniques
IRMS, ICP-MS, Noble gas MS, electron microprobe
- specific sample prep labs for Radiocarbon, Radiohalides, Exposure age
dating, noble gases and stable isotopes
For Bio-medical and Pharmaceutical Sciences:
- separate ion source lines to accommodate higher levels of tracer isotopes
- gas ion source capability for interface to other analytical instruments, e.g.
•
•
elemental analyzer for rapid or survey 14C work
GC or HPLC for compound specific 14C work
For Anthropological and Cultural Sciences:
- similar to earth & planetary science requirements
Design Goals
For AMS Research:
- flexible accelerator and peripheral design
- accessible control electronics and software
- sufficient floor space for tests of new injection and detection systems
- support for continuation of research and development projects
inherited from IsoTrace and beyond:
a) Negative Ion Chemistry in the Ion Source
b) Integrated 14C Sample Preparation and Analysis
c) Reaction Cells and Isobar Separation
d) Laser – ion interactions ?
2. Advances in AMS Technology
a) Enhanced Production of Negative Ions
or Chemistry in the Ion Source
Many elements do not readily make negative atomic ions
But molecular ions can be used to carry the analyte to the
accelerator terminal
Fluoride materials make very strongly bound negative molecular ions
and tend to produce much higher currents than those from the pure
metal
Zhao et al Nuclear Instruments & Methods B 268 (2010) 807–811
Examples in the following two papers:
Adam Sookdeo, using PbF2 to develop a technique for measuring 210Pb
Cole MacDonald, using CsF2 to develop a technique for measuring
135Cs and 137Cs
New AMS Technology
b) Ion - gas reactions to reduce isobar interferences:
Early work done with negative ions in a simple gas volume (Ferguson et al,
Chem. Phys. Lett. 15 (1972) 257–259.) showed a chemical dependency of the
negative ion destruction cross section.
Work by Doupé, Tomski and Javahery confirmed that S– in a beam of Cl– could
be selectively destroyed in NO2.
Funding for a Proof-of-Principle instrument and a patent obtained and the
“Isobar Separator for Anions (ISA)” was built successfully tested.
System schematic
High Voltage Deck
New AMS Technology
Version uses a single cell for both cooling and reactions
Lab Ground
Deceleration
Lenses
Deceleration
Quads
Cooling / Reaction
Cell
Acceleration
Quad, Lenses
Lab Ground
To Accelerator
New AMS Technology
System as built –configuration used at IsoTrace
Off-axis Faraday Cup
Vacuum Box
Ion Source
High Voltage Deck
(behind lucite shield)
New AMS Technology
Isobarex Corp. formed to develop and market ISA technology
Isobarex and the Lalonde AMS Lab are collaborating on the installation of a precommercial, demonstration version of the ISA.
Entrance Einzel Lens
Interchangeable ISA Column
Exit Einzel Lens
Vacuum Baffle
Electronic
Card Cage
High Voltage Deck
Insulator
Stable Beam
Attenuator Box
Dual Stage Turbo Pump
New AMS Technology
Lalonde Lab Overall System
Innovation Injector Line
(U of Toronto components,
Isobarex ISA column)
3 MV Multi-Element AMS system, built by High Voltage
Engineering BV
SIMS-type
Ion Source
20° Second High
Energy Magnet
SO-110-200 Ion Source
2 anode
Ionization
Detector
65° Cylindrical
Electric Analyzer
Isobar
Separator
SO-110-200
Ion Source
Faraday Cup Box
54° Rotatable
Electric Analyzer
ρ = 1.52 m
Inflection
Magnet
120° Spectrometer Magnet
to accept 339 AMU at full
source energy
Additional turbopump and
differential section for
terminal stripper
90°, 351 MeV-AMU
Analyzing Magnet
uOttawa Advanced Research Complex
André E. Lalonde AMS Laboratory
Investigators, Affiliations and Acknowledgements
A. E. Litherland
IsoTrace Laboratory, University of Toronto
Ian D. Clark
W. E. (Liam) Kieser
R Jack Cornett
Xiao-Lei Zhao
Gilles St-Jean
Chris Charles
A. E. Lalonde AMS Laboratory,
University of Ottawa
Lisa Cousins
Gholamreza Javahery
Ilia Tomski
Ionics Mass
Spectrometry Group
Jean-François Alary
Chris Charles
Isobarex Corp
Funding from:
NSERC MRS, I2I and Discovery Grants
Canada Foundation for Innovation
Ontario Research Fund