Seeking clarity

So after processing and retrieving all the sodium from the water, quantifying the concentration of 22Na provided another challenge. To do this, I used a scintillation cocktail. As the 22Na deyaed, it released beta particles. These particles interact with the cocktail and cause it to flash. By counting these flashes, I could determine the quantity of 22Na in the sample.


A diagram showing the 22Na decay scheme into its daughter product, 22Ne. (Lauer, 2013)


I would count these beta emissions for anywhere from 3-4 days to one week, with 90% efficiency. Previous students counted gamma emissions, which had a much lower efficiency (~3%) and required counting for weeks to amass enough data.


So, wonderful – I was working with an improved method! Naturally, there were still hurdles to overcome. The cocktail used in the past was Ultima Gold XR, a liquid scintillation cocktail with a high load capacity. This meant it could handle large concentrations of sodium and still perform well. However, we found that sometimes this was not the case. We occasionally had sodium concentrations that were too high, and the cocktail failed to mix properly. In order to properly see the cocktail fluoresce, the sample must be completely clear. Often samples turned cloudy – I experimented (an am still experimenting) with different scintillation cocktails, container volumes, and sample concentrations to perfect this stage.

A breakdown of typical scintillation cocktail results/issues. (SCK-KEN, 2008)