1. NE 301 - Introduction to Nuclear Science Spring 2012 Classroom Session 6: Rates of Nuclear Decay Transient Equilibrium Secular Equilibrium No Equilibrium Branching Growth of Products in a Neutron Flux Transient Equilibrium Secular Equilibrium No Equilibrium Radiation Interaction with Matter

2. Reminder Load TurningPoint Reset slides Load List Homework #1 due on Thursday How to measure half-lives document 2

3. Products in a Decay Chain 3

4. Solution: 4 If N B0 =0

5. Transient Equilibrium If parent T 1/2 >3-10 times daughter T 1/2 5

6. Example Radionuclide Generator Every time the “cow” is “milked” by running eluting solvent, activity of 99m Tc drops.

7. Secular Equilibrium If parent T 1/2 >> 10 times daughter T 1/2 7 It is useful to calculate the half-life of long- lived isotopes. For example for 238 U 238 U  234 Th  234 Pa and 234 Th T 1/2 =24.1d

8. No Equilibrium 8 If parent T 1/2 < daughter T 1/2 no equilibrium Parent decays Daughter increases then decays too

9. General Decay Chain – Bateman Equations 9 Two assumptions: 1. only parent at t=0. 2. no i ’s are equal

10. Branching Often observed in the odd-odd line of  -stability 10

11. Growth of Radioactive Products in a Neutron Flux 11

12. Growth of Radioactive Products in a Neutron Flux 12 Notice saturation after 3-5 times T 1/2 radioactive product. Notice saturation after 3-5 times T 1/2 radioactive product. Additional irradiation time does not increase activity. Additional irradiation time does not increase activity.

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