01:160:162 Lecture 36: Radioactivity and Fission
25 Jul 2017
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Document Summary
High e particles emitted by radioactive nuclei can be readily detected (1) film badge dosimeters. Exposure to photographic films (2) scintillation counters. Particles emitted by radioactive nuclei pass through an argon filled chamber. Argon atoms become ionized and complete a circuit within the detection chamber causing an electrical signal. Signal is displayed by a meter or as an audible click. All radioactive nuclei decay via first-order kinetics. Differential rate law: rate = k n. Decay rate in units of number of decaying nuclei per unit time. Higher rate constant = faster decay rate. Different nuclei decay with different rate constants. For radioactive decay, k is independent of temperature. Higher value of n = faster decay rate. Half-life of radioactive nuclei time it takes for one-half of the parent nuclide to decay to daughter nuclide. First order integrated rate law for radioactive decay: Nt = number of radioactive nuclei remaining at time (t) No = initial number of radioactive nuclei.
