Problem 6.9

A narrow beam of alpha particles with kinetic energy \(1.0 \mathrm{MeV}\) falls normally on a platinum foil 1.0 \( \mu \) m thick. The scattered particles are observed at an angle of \(60^{\circ}\) to the incident beam direction by means of a counter with a circular inlet area \(1.0 \mathrm{~cm}^{2}\) located at the distance \(10 \mathrm{~cm}\) from the scattering section of the foil. What fraction of ecottoi reaches the counter inlet?