Step 1. Weigh a sample and a standard in quartz tubes.
[Illustration: Piece of plastic; Standard = sodium carbonate]
Step 2. Seal tubes in package for reactor irradiation.
[Illustration: Sealed aluminium can; Sealed quartz tubes; Sample;
Standard]
Step 3. Bombard with neutrons for about 3 hours in a reactor.
[Illustration: Neutrons]
Step 4. Remove sample and standard from tubes and place in separate
plastic containers to measure gamma rays.
[Illustration: Pulse height analyser; Sample; Standard; Gamma rays from
Na-24; same container, distance, detector; Sodium iodide scintillator]
Step 5. Obtain gamma-ray spectrum for sodium-24 in both sample and
standard.
[Illustration: (chart) Energy vs. Sample spectrum; Energy —→Standard
spectrum]
Step 6. Use standard to calculate 1.37 MeV gamma rays counted per minute
per gram of sodium (c/m/gNa).
c/m/gNa = (counts/minute measured in 1.37 peak (shaded area
above))/(grams of sodium known to be in standard (step 1.))
Step 7. Use c/m/gNa and 1.37 MeV gamma rays counted per minute in sample
to calculate grams of sodium in sample.
grams Na in sample =
(counts/minute measured in sample)/(c/m/gNa (step 6.))
Step 8. Calculate percent sodium in sample.
% sodium =
(grams sodium in sample (step 7.))/(weight of sample (step 1.)) × 100