Problem 6.10

A narrow beam of alpha particles with kinetic energy \(T\) \(=0.50 \mathrm{MeV}\) and intensity \(I=5.0 \cdot 10^{5}\) particles per second falls normally on a golden foil. Find the thickness of the foil if at a distance \(r=15 \mathrm{~cm}\) from a scattering section of that foil the flux density of scattered particles at the angle \(\theta=60^{\circ}\) to the incident beam is equal to \(J=40\) particles \(/\left(\mathrm{cm}^{2} \cdot \mathrm{s}\right)\)