In scattering experiment , find the distance of closest approach , if a 6 MeV `alpha`-particle is used

In the Geiger-Marsden scattering experiment find the distance of closest approach to the nuclcus of a 7.7 Mev alpha -particle before it comes momentaily to rest and reverses its direction. (Z for gold nucleus = 79 )

(A) The positively charged nucleus of an atom has a radius of almost 10^(-15) m : (R) : In alpha -particle scattering experiment, the distance of closest approach for a - particles is ~= 10^(-15) m.

Write the expression for distance of closest approach for a alpha -particle.

Find the distance of closest approach when a 6 MeV proton approaches a gold nucleus.

The distance between the a-particle and target nucleus in an alpha -scattering experiment is equal to distance of closest approach, when the scattering angle is