# Sweet Sweet gamma rays

1. Nov 9, 2009

### nerdgirl

1. The problem statement, all variables and given/known data
A gamma ray from 198Au incident normally on a thick aluminum slab travels 1.45 cm before it undergoes a Compton scattering. Calculate the range of angles through which the gamma could scatter and still have at least a 10% probability of re-emerging from the incident slab surface without undergoing another interaction.

2. Relevant equations
the mass attenuation coefficient for Al at 1.5 cm is .05 MeV
E$$\gamma$$' = Ey / [1 + (E$$\gamma$$/E0) (1-cos$$\vartheta$$)

3. The attempt at a solution
IIn the chart of the nuclides do I use one of the gamma energies or is this even the first formula I should be using?