Liam Kieser, Ian Clark, Jack Cornett and Xiaolei Zhao, University of Ottawa

1. 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

2. Overview A. E. Lalonde AMS Lab • Introduction – What is AMS? a) Basic Description – Advantages, Applications, Challenges b) Lab Photo Tour – Principal Components c) Critical Component – the ion source • 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 • Advances in AMS Technology a) Negative Ion Chemistry in the Ion Source b) Ion-Gas Reactions and Isobar Separation The New Facility at uOttawa - Summary

3. Accelerator Mass Spectrometry (AMS) A synthesis of: Conventional mass spectrometry, and Particle accelerator technology -- usually a tandem electrostatic accelerator Filter or Analyzer Advantages: • Molecular interference free measurements Heavier Ions Ion Source (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) Lighter Ions Ions Detector Sample • Atomic isobar elimination is special cases 14C (14N), 26 Al (26Mg), 129I (129Xe), 202Pb (202Hg)

4. 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)

5. 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 Magnetic Analyzer Tandem Accelerator

6. Accelerator Mass Spectrometry (ctd) AMS System: View from Low Energy End

7. Accelerator Mass Spectrometry (ctd) AMS System: View from above the High Energy End

8. The Ion Source Requirements: • Produce negative ions from a wide range of elements Source Head Base -28kV 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) -35 kV • Stable operation for a variety of sample matrices • Relatively low memory of previously analysed samples Extraction Cone (ground potential) • Development of the negative ion caesium sputter source in the 1970smade AMS possible Caesium Vapour feed

9. Ion Source HVE SO-110 200 sample, solid/gas ion source Electric Analyser Sample Carousel Source Head

10. Ion Source: Source HeadFlange In Place On Maintenance Stand Target Cooling Lines Caesium Vapour Feed Caesium Ionizer Target holder Target holder -35 kV Source head base / support -28 kV

11. Ion Source: Target Wheel – capacity: 200 targets in 4 circles of 50 – access time to neighbour- ing target: ~2 seconds

12. 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 micro- environment for the conversion of CO2 into negative carbon ions – one assembly must be prepared for each 14C measurement

13. 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

14. 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 ?

15. a) Enhanced Production of Negative Ions 2. Advances in AMS Technology 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 B268 (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

16. 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

17. New AMS Technology Version uses a single cell for both cooling and reactions Deceleration Lenses Deceleration Quads Cooling / Reaction Cell Acceleration Quad, Lenses Lab Ground Lab Ground To Accelerator

18. New AMS Technology System as built –configuration used at IsoTrace Off-axis Faraday Cup Vacuum Box High Voltage Deck (behind lucite shield) Ion Source

19. New AMS Technology Isobarex Corp. formed to develop and market ISA technology Interchangeable ISA Column Isobarex and the Lalonde AMS Lab are collaborating on the installation of a pre-commercial, demonstration version of the ISA. Exit Einzel Lens Entrance EinzelLens VacuumBaffle Electronic Card Cage High Voltage Deck Insulator Dual Stage Turbo Pump Stable Beam Attenuator Box

20. 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 2 anode Ionization Detector SO-110-200 Ion Source 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 90°, 351 MeV-AMU Analyzing Magnet Additional turbopump and differential section for terminal stripper

21. Investigators, Affiliations and Acknowledgements uOttawa Advanced Research Complex André E. Lalonde AMS Laboratory Funding from: NSERC MRS, I2I and Discovery Grants Canada Foundation for Innovation Ontario Research Fund