[QUE/EM-01007] --- EM-PROBLEM

For an alpha particle approaching a nucleus of charge \(Ze\) from
a large distance with energy \(E>0\) and having impact parameter \(b\).
Find the distance of closest approach as function of energy and
impact parameter.

Answer {\(\frac{k+\sqrt{k^2+4E^2b^2}}{2E}\)}