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NOSAMS Home
> AMS Development
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Development of a Continuous-Flow
AMS System
Mark Roberts Staff Physicist
assembles the gas-ion source at the 0º port |
Continuous-Flow
AMS
Under a NSF Major Research Instrumentation (MRI) award,
NOSAMS is building a new AMS system designed specifically
for continuously monitoring 14C
in a flowing gas stream. The instrument will be capable
of continuously analyzing chromatographic effluents and
determining the abundance of 14C
in individual chromatographic peaks. This system will
enable a dramatic expansion of significant and well-established
lines of inquiry including: (i) surveys of the
distribution of radiocarbon among natural products and
thus of the sources of those materials, (ii)
quantification of 14C
tracers at extraordinary levels of dilution, and (iii)
sensitive recognition of fossil-fuel-derived pollutants
in natural systems by exploiting their zero content of
14C as a ‘negative
label’. |
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Development of a Gas-Ion Source
Albert Benthien and Baoxi Han
Post-docs 2004 with the gas-ion source |
Gas-Ion Source
NOSAMS has been exploring the capabilities of a gas-accepting
microwave ion source originally built at the Atomic Energy
of Canada, Chalk River Laboratories. The source uses 2.45
GHz microwaves and a continuously flowing stream of argon
gas to sustain a plasma. Carbon containing gases mixed
into the argon yield C+
ions that can be extracted as an ion beam. Negative ions
are obtained by passing the beam through a magnesium charge-exchange
canal. Initial success with this ion source has led to
the design of a new gas-ion source. |
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Collaborative
Efforts to Improve NEC Ion Source
Karl von Reden Staff Physicist
loads samples |
Improvements to NEC Ion Source
A collaborative research effort involving National Electrostatics
Corp. (NEC) and three AMS laboratories (UC Irvine, University
of Arizona, WHOI/NOSAMS) is underway to improve the design
of Cs-sputter ion sources manufactured by NEC and currently
in use at each of these labs. The NSF-sponsored collaboration
is supported for the two-year period beginning in August,
2003. |
Development of Carbon Stripper
Foils
Enid Sichel Adjunct
Scientist & Karl von Reden examine a nanotube
foil with an atomic force microscope
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Nano-tube Stripper Foils
Over the last decade, research on single-walled carbon
nanotubes (cylindrical closed structures of graphitic
carbon, ~1.2 nm diameter) has revealed remarkable properties:
high electric and thermal conductivity and tensile strength
far exceeding that of steel. That has led Karl von Reden
and Enid Sichel to the idea of developing a durable carbon
nanotube foil for electron stripping in accelerator mass
spectrometry (AMS). The idea is to create thin mats of
nanofibers into a mesh configuration that would perform
like a “frozen gas”, keeping the stripping
atoms largely stationary under ion beam bombardment and
minimizing the structural damage known to occur in amorphous
or graphitic films. |
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