SUERC AMS Laboratory

SUERC AMS Laboratory

Accelerator mass spectrometry (AMS) is ultrasensitive isotope ratio mass spectrometry of small prepared samples. By accelerating sample atoms the ions can be characterised by combined conventional mass spectrometry and high-energy collisions within and after the accelerator. Isotopes typically measured include a handful of lowly abundant long-lived radionuclides. The AMS Laboratory specialises in environmental science measurement of these natural chronometers and undertakes research in pursuit of this.

The laboratory is equipped with two modern NEC accelerator mass spectrometers and five available sputter, plasma and microprobe ion sources accommodating solid and gas samples. The general purpose 5 MV instrument has established capability for 10Be, 14C, 26Al, 36Cl, 41Ca and 129I-AMS. The 250 kV machine is for 14C-AMS too but is bipolar and also makes experimental measurements of accelerated positive ions. Much analysis is done at the low ion energy limit of the technique, including use of ultrathin SiN detector entrance windows for heavy-ion analysis.

The AMS Laboratory performs about 7,000 analyses a year with collaborators including the SUERC Radiocarbon Laboratory, the NERC Radiocarbon Facility (East Kilbride), the Glasgow University Cosmogenic Nuclide Laboratory, the NERC Cosmogenic Isotope Analysis Facility - all at SUERC - and the University of Edinburgh Terrestrial Cosmogenic Nuclide Laboratory. Samples prepared further afield are also accepted.

The AMS group is Stewart Freeman, Sheng Xu, Drew Dougans, Richard Shanks, Paul Gallacher, Pauline Gulliver, Brian Tripney, Derek Fabel and Cameron McIntyre.

For more information and collaboration with cost recovery please contact Prof. Freeman. Consortium university members can enjoy special access.

Species
Precision
Background
Comment
10Be
1-3%
10Be/Be<1e-15
Carrier limits background
Low current 14C
1-3‰
>70,000 years
Slow measurement of >100 µg C with on-line δ13C determination
Medium current 14C
Routine measurement of >500 µg C
High current 14C
3‰
Fast measurement dependent on graphite quality
CO2 14C
~50,000 years
Analysis of >10 µg C but limited by few atoms
in small/old samples
26Al
1%
26Al/Al<1e-15
Measurement statistics usually limits precision
36Cl
3%
36Cl/Cl<1e-15
Ion source memory limits background
On-line 37Cl/35Cl measurement of spiked-carrier
41Ca
1%
41Ca/Ca=1e-14
Samples as readily preparable CaF2
129I
2%
129I/I=1e-13
Ion source memory limits background