How do we detect gamma rays?

• Review:

• What is each peak?

• Why are they there?

• Calculate the location of the Compton edges and backscattering!

1.17 MeV and 1.33 MeV

Five Minute Questions

Review gamma spectroscopy data

PhotoelectonsCompton EdgeBack ScatteringPair ProductionX-ray Production

Simple models of atoms – Evolution in our thought…

Thompson’s plum pudding model – photon spectrum?

Rutherford ScatteringBohr’s atom in all its gloryX-ray spectra

Five Minute Question #1.•Gauss’ Law

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You have sphere of uniform charge. (The charge is spread out evenly throughout the sphere.) The charge is Q. The radius is R.

•What is the Electric Field strength at point A where the distance from A to the center of the sphere is rA (rA > R).

•What is the Electric Field strength at point A where the distance from A to the center of the sphere is rB (rB = R).

•What is the Electric Field strength at point A where the distance from A to the center of the sphere is rC (rC < R).

Five Minute Question #2Start the calculation to find the radius of orbit of a geosynchronous satellite. (Start with Newton’s second Law. Then use Newton’s law of Gravity and centripetal acceleration!)

Chapter 6 – Based on experiments, how can we learn about atoms and their internal structure?

Model #1 – Plum Pudding

What force does a raisin (q=-e) at a radius, r, feel from the pudding?•Attractive to center•No force at the center•Oscillatory – specific frequency