Case study Caesium-137 (137Cs) is an isotope that has practical uses due to its radioactive properties. Besides the traditional dating applications of radioactive material, Caesium-137 is also used in calibration of radiation-detection equipment and in medical radiation therapy. This isotope has very stable statistical properties and its decay can be accurately modeled by the previous stochastic model. It has a half-life 30.17 years. 3. Find the decay constant for 137 Cs expressed in s 1. 4. With this, find the probability P(0