Determination of 137Cs half-life with an ionization chamber

The half-life of 137Cs was measured with an ionization chamber by following the decay of 5 sources over a 30 years period between 1983 and 2013. The ratio between the ionization chamber current for the cesium sources and 226Ra source was used for the half-life calculation. The value found for the 137Cs half-life is 10,955.2±10.7 days, where the uncertainty evaluation combines type A and B for one standard deviation.