Determination of half-life of Cs-137 - Recording and evaluating the decay and production curve with CASSY

In the experiment P6.4.3.4, a plastic bottle with radioactive Cs-137 is used. The Cs-137 continually decays into Ba-137m. The metastable isotop Ba-137m arising from the β-decay is selectively washed out by a syringe with eluation solution. The half-time amounts to 2.6 minutes approx.

Using two counter tubes, we can first observe the eluation transfer of radioactive Ba-137m out of the plastic bottle into the test tube. Inside the test tube, the Ba-137m will decay exponentially over time within a few minutes, at the same time, the activity of Ba-137m inside the plastic bottle will build up again. In the end, there is again a dynamic equilibrium of decay and production in the plastic bottle.