Speaker
Description
Movements of nuclear contamination through the world's oceans, and natural radioactive decay in ancient deep-subsurface ground waters, can be traced by $^{127}$I/$^{129}$I and $^{236}$U/$^{238}$U isotopic composition (IC) measurements. Accelerator mass spectrometry (AMS) remains the technique of choice for such IC determinations at ultra-trace levels (i.e. $<$ 1$\times$10$^{-13}$), with a key requirement that long-lasting high current negative ion beams of those elements must be produced from solid samples in Cs$^+$ sputter-ion sources. Here, I discuss ion source and sample chemistry developments that significantly increased negative ion currents of $^{129}$I and $^{236}$U on the 3 MV tandem AMS at uOttawa, allowing precise and accurate $^{127}$I/$^{129}$I and $^{236}$U/$^{238}$U IC determinations in waters from (A) the Beaufort Sea (Arctic Ocean) between 0 to -4000 m depths for tracing the movements of nuclear reprocessing waste, and (B) Kidd Creek Mine (Timmins, ON) at $\sim$8000 ft depth, to identify radioactive decay as a radiolytic energy source in the world's oldest known isolated ground water.
| Email address | crj.charles@gmail.com |
|---|---|
| Funding Agency | NSERC |
| Classification/Track | Invited |
| Visitor's Visa | no |
| Classification | Applications of Negative sources - medical (diagnostics, therapy), industrial (implantation, materials analysis, carbon dating, discovery science |