(In
a beam, all particles have nearly same
kinetic energy ) It is seen that an a-particle
close to the nucleus (small impact
parameter) suffers large scattering In case
of head-on collision, the impact parameter
is minimum and the a-particle rebounds
back (q  @ p) For a large impact parameter,
the a-particle goes nearly undeviated and
has a small deflection (q  @ 0)