Problem 6.13

A narrow beam of protons with velocity $v=6 \cdot 10^{6} \mathrm{~m} / \mathrm{s}$ falls normally on a silver foil of thickness $d=1.0 \mu \mathrm{m} .$ Find the probability of the protons to be scattered into the rear hemisphere $\left(\theta>90^{\circ}\right)$