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 NEC accelerator mass spectrometers and three sputter ion sources accommodating solid 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), SUERC-Cosmo (including NEIF Cosmogenic Nuclides) - 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, Derek Fabel, Richard Shanks, Cameron McIntyre, Pauline Gulliver, Brian Tripney and Thomas Donoclift.
For more information and collaboration on 10Be and 26Al please email Derek Fabel.
For more information and collaboration on 36Cl please email Richard Shanks.
For more information and collaboration on 41Ca and 129I-AMS please email Stewart Freeman.
Species
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Precision
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Background
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Comment
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10Be
|
1-3%
|
10Be/Be<1e-15
|
Carrier limits background
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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
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Samples as readily preparable CaF2
|
129I
|
2%
|
129I/I=1e-13
|
Ion source memory limits background
|