A shadow of the repulsive Rutherford scattering and Hamilton vector

The fact that repulsive Rutherford scattering casts a paraboloidal shadow is rarely exploited in introductory mechanics textbooks. Another rarely used construction in such textbooks is the Hamilton vector, a cousin of the more famous Laplace-Runge-Lenz vector. We will show how the latter (Hamilton's vector) can be used to explain and clarify the former (paraboloidal shadow).