Ph 490

March 5, 2003

Problem Set 6

Problem 1. Cesium-137 decays emitting a gamma-ray of energy 0.661 MeV. What is the maximum energy given an electron when this gamma-ray scatters from an electron via the Compton effect?

Problem 2. The neutron howitzer produces gamma rays through the neutron-capture reaction

n + p -> d + g .

Here are the masses of the n, p and d, in standard particle-physics units:

proton 938.27200 MeV/c²

neutron 939.56533 MeV/c²

deuteron 1875.629 MeV/c²

(a) Calculate the energy of the gamma ray, in MeV.

(b) Sketch the pulse-height spectrum expected from a NaI[Tl] detector with these gamma rays incident. Indicate specifically those peaks corresponding to production and annihilation of matter.