Liam Kieser, Ian Clark, Jack Cornett and Xiaolei Zhao, University of OttawaTed Litherland, University of Toronto

Instrumentation Session, CAP 2014 Congress, Laurentian University, June 17

The André E. Lalonde Accelerator Mass Spectrometry Lab

at the University of Ottawa

1. Introduction – What is AMS?

b) Ion-Gas Reactions and Isobar Separation

3. Advances in AMS Technology

Overview

4. The New Facility at uOttawa - Summary

a) Negative Ion Chemistry in the Ion Source

a) Basic Description – Advantages, Applications, Challengesb) Lab Photo Tour – Principal Componentsc) Critical Component – the ion source

a) Earth and Planetary Sciences2. Design Goals for the Lalonde Lab

b) Bio-medical and Pharmaceutical Sciences

A. E. Lalonde AMS Lab

c) Anthropological and Cultural Sciencesd) AMS Research and Innovation

Accelerator Mass Spectrometry (AMS)A synthesis of:

Conventional mass spectrometry, Particle accelerator technology -- usually a tandem

electrostatic accelerator

and

Advantages:■ Molecular interference free measurements

(Molecules destroyed in the charge changing process)

■ Measurements with extremely low dark current(High energy -- 100s of keV to 10s of MeV provide single atom counting capability and some degree of atom identification)

■ Atomic isobar elimination is special cases14C (14N), 26 Al (26Mg), 129I (129Xe), 202Pb (202Hg)

Ion Source

Filter or Analyzer

Sample Detector

Ions

Heavier Ions

Lighter Ions

Applications:

Challenges:•Need to make negative ions of the analyte

(Tandem accelerator operation)

•Atomic isobars can be difficult to eliminate(except in the special cases)

•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

•Used in Archaeometry, Astrophysics, Biology, Bio-medical research and clinical practice, Earth, Environmental and Planetary science, Materials research, Pharmacology

•Some sample materials require extensive, labour-intensive preparatione.g. 10Be, 14C

•Levels ranging from 1 part in 1010 to 1 part in 1016

Accelerator Mass Spectrometry (ctd)

AMS System Schematic:

Tandem Accelerator

Low Energy MassSpectrometry

Negative Ion Source

High EnergyMass Spectrometry

Gas Ionization Detector for rare species

Faraday Cups for abundant species

Sample

Gas-Filled ElectronStripper Canal

3 MV Power Supply

Electric Analyzer

Magnetic Analyzer

Magnetic Analyzer

Electric 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

Accelerator Mass Spectrometry (ctd)

The Ion Source

→Development of the negative ion caesium sputter source in the 1970s made AMS possible

Requirements:

►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 ►Stable operation for a variety of sample matrices►Relatively low memory of previously analysed samples

►Produce negative ions from a wide range of elements

Extraction Cone (ground potential)

Sample (Target)-35 kV

Caesium IonizerSource Head Base -28kV

Caesium Vapour feed

Ion Source

HVE SO-110 200 sample, solid/gas ion source

Sample Carousel

Source Head

Electric Analyser

Ion Source:

Source Head Flange

Target Cooling Lines

Caesium IonizerTarget holder

Caesium Vapour Feed

On Maintenance Stand In Place

Source head base / support -28 kV

Target holder -35 kV

Target Wheel

– capacity: 200 targets in 4 circles of 50

– access time to neighbour-ing target: ~2 seconds

Ion Source:

Target Assembly

– provides the micro- environment for the conversion of CO2 intonegative carbon ions– one assembly must be prepared for each 14C measurement

For solid materials– compress into a 1.3 mm Φ

pellet in a replaceable Al or SS cylinder

For gases

Ion Source:

A. E. Lalonde AMS Lab Design Goals

For Earth and Planetary Sciences:

For Bio-medical and Pharmaceutical Sciences:

For Anthropological and Cultural 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

- separate ion source lines to accommodate higher levels of tracer isotopes- gas ion source capability for interface to other analytical instruments, e.g.

- specific sample prep labs for Radiocarbon, Radiohalides, Exposure age dating, noble gases and stable isotopes

• elemental analyzer for rapid or survey 14C work• GC or HPLC for compound specific 14C work

- similar to earth & planetary science requirements

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:

c) Reaction Cells and Isobar Separation

b) Integrated 14C Sample Preparation and Analysis

a) Negative Ion Chemistry in the Ion Source

d) Laser – ion interactions ?

Design Goals

a) Enhanced Production of Negative Ions

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

or Chemistry in the Ion Source

Zhao et al Nuclear Instruments & Methods B 268 (2010) 807–811

2. Advances in AMS Technology

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

System schematic

High Voltage Deck

b) Ion - gas reactions to reduce isobar interferences:

New AMS Technology

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.

Version uses a single cell for both cooling and reactions

Lab GroundDeceleration

LensesDeceleration

QuadsCooling / Reaction

CellAcceleration Quad, Lenses Lab Ground

To Accelerator

New AMS Technology

System as built –configuration used at IsoTrace

High Voltage Deck(behind lucite shield)

Off-axis Faraday Cup Vacuum Box

Ion Source

New AMS Technology

Exit Einzel LensEntrance Einzel Lens

Electronic Card Cage

Vacuum Baffle

High Voltage DeckInsulator

Stable Beam Attenuator Box Dual Stage Turbo Pump

Interchangeable ISA Column

Isobarex and the Lalonde AMS Lab are collaborating on the installation of a pre-commercial, demonstration version of the ISA.

New AMS Technology

Isobarex Corp. formed to develop and market ISA technology

Lalonde Lab Overall System

New AMS Technology

SIMS-typeIon Source

Innovation Injector Line(U of Toronto components,

Isobarex ISA column)

3 MV Multi-Element AMS system, built by High Voltage Engineering BV

IsobarSeparator

ρ = 1.52 m Inflection Magnet

SO-110-200 Ion Source

SO-110-200 Ion Source

120° Spectrometer Magnetto accept 339 AMU at full

source energyAdditional turbopump and

differential section for terminal stripper

90°, 351 MeV-AMU Analyzing Magnet

65° Cylindrical Electric Analyzer

20° Second High Energy Magnet

2 anode Ionization Detector

Faraday Cup Box54° Rotatable

Electric Analyzer

Investigators, Affiliations and Acknowledgements

Ian D. ClarkW. E. (Liam) KieserR Jack CornettXiao-Lei ZhaoGilles St-JeanChris Charles

A. E. Lalonde AMS Laboratory,University of Ottawa

Lisa CousinsGholamreza JavaheryIlia Tomski

Ionics MassSpectrometry Group

Funding from: NSERC MRS, I2I and Discovery Grants Canada Foundation for Innovation Ontario Research Fund

uOttawa Advanced Research ComplexAndré E. Lalonde AMS Laboratory

Jean-François AlaryChris Charles

Isobarex Corp

A. E. Litherland IsoTrace Laboratory, University of Toronto