Report from the Early Career Researcher Exchange with Business and Industry
Dr Richard P. Shanks
Accelerator Mass Spectrometry Laboratory,
Scottish Universities Environmental Research Centre (SUERC),
Scottish Enterprise Technology Park, East Kilbride, G75 0QF, U.K.
Contact email: [email protected]
Introduction
In 2014, SAGES funded me to undertake an industrial exchange with Pantechnik in
France. Pantechnik are the manufacturers of electron cyclotron resonance (ECR) ion
sources, which are used to create high quality, large current, positively charged ion
beams in various charge states.
The project is to develop this ion source for application in accelerator mass
spectrometry (AMS). AMS is an essential tool for the measurement of rare
radionuclides in the geosciences, e.g. radiocarbon and cosmogenic isotopes. Rare
radionuclides are utilised in all three of the SAGES themes and have many
applications that include oceanography, hydrology, exposure-age and burial dating,
climate change and landscape evolution, to name just a few. AMS is an extremely
sensitive mass spectrometry technique that is not only able to resolve different masses
but also able to separate interferences of the same mass. For example, 14C can be
separated from 14N and from molecules such as 13CH 12CH2 etc. One of the primary
limitations of this measurement technique is the low efficiency and beam current
generated in the conventional caesium sputter, negative ion source. Using an ECR for
AMS will lead to improved system performance that will allow, for example,
geoscience users to make measurements with increased precision and sensitivity, on
smaller sample sizes and over a larger radionuclide concentration (and therefore age)
range.
A research agreement has been set-up between the University of Glasgow and
Pantechnik that provides a long-term loan of an ECR ion source to evaluate its
potential in AMS. The work to evaluate and develop the use of the positive ion source
in accelerator mass spectrometry was carried out by Prof Stewart Freeman and myself
at the NERC recognised facility AMS laboratory in SUERC.
Achievements
At Pantechnik I worked closely with the responsible engineers to create a two-way
knowledge share about both AMS and the ECR source and develop methods of
combining the two. While there I was trained on the ECR source and shown how to
operate the ion source and tune its output to the requirements of the AMS system. In
cooperation with Pantechnik, I was also able to adapt and develop the design of the
ECR source so that it can be integrated in our AMS system at SUERC
On my return to SUERC I have used my knowledge and skills obtained at Pantechnik
to install and integrate the ECR ion source in our AMS system at SUERC, as shown
in Figure 1. I then further developed the AMS system and ECR ion source to carry out
the first ever, environmental level radiocarbon measurements from a positive ion
source. The University of Glasgow has now filed a patent application for this system
to protect the intellectual property. After the patent application had been filed the
result was announced at the international AMS conference (AMS-13) where it was
recognised by the community as the “highlight of the conference”.
Figure 1: the ECR ion source (left) and the conventional Cs sputter ion source
(right) with the primary bending magnet in the foreground. (5 million volt
tandem accelerator in the background.)
During my return visit to Pantechnik I was able to use the initial results of the positive
ion mass spectrometry (PIMS) system and the expertise at Pantechnik to further
develop experiments to understand the ion source behaviour in AMS. We found that
the carrier gas plays an important role on interacting with the same gas to absorb
hydrogen and reduce the problematic 13CH interference. This will allow us to further
optimise the ECR ion source for improved future performance and also provides key
information required for the design of the next generation of ECR ion source,
specifically designed for this application.
Pantechnik and I have worked together to develop the key principles of the prototype
system (as shown in Figure 2) along with a detailed estimate of the cost of
development. This costing, along with the proof of principle results, has been used to
submit a NERC grant application. The NERC funding is to build a dedicated
development machine, which will have significant advantages of the current
technology.
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Figure 2: schematic of the prototype positive ion mass spectrometry (PIMS) system.
Additionally, work has been started on the first cosmogenic AMS from a positive ion
source. This technique is complicated by aluminium not readily forming a gas, which
the ECR ion source usually consumes. It is therefore necessary to vaporise solid
aluminium directly into the ion source. During my time spent at Pantechnik I
produced a positive ion beam from a solid sample. Now that this technique has been
developed during my exchange, it should now be possible to carry out full Al AMS.
Conclusions
My industrial placement with Pantechnik has resulted in the proof of principle
measurement and first ever demonstration of environmental level radiocarbon
measurements from a positive ion source. This result has been very well received at
an international conference and resulted in the filing of a patent application for the
technology. The patent has already received interest from several companies to
manufacture the machine. The developments in the technique will result in exciting
new areas of research for geoscientist whereas the compact and simple nature of the
development compared to existing technologies will result in more scientist gaining
access to the technology.