How Accurate Are My Calculations on Alpha Particle Scattering and Energy?

[Hayool]

Hi,

I calculated the scattered angle & the kinematic factors for both Al & Au to be

Is what I did right?
Also

E (Alpha) = stopping power x depth
= 250 x 0.5 = 125 keV
As for the maximum & the minimum scattered energy i didn't know how?

 

[Hayool]

Any feedback would be appreciated, I'm really struggling.