TABLE OF CONTENTS As we have seen, the scattering of a particle in a potential is completely determined once we know the impact parameter and the energy of the particle; and, for a fixed incident energy, the deflection is therefore defined by just the impact parameter. To perform an experiment, we prepare an incident flux of beam particles of known energy, and measure the number of particles scattered out of the beam at different ?. Because this number is determined entirely by the impact parameters involved in the collisions, such measurements reflect these impact parameters and thereby the range of the interaction and the effective size of the scattering center.
Let N 0 denote the number of particles incident on the target foil per unit area per unit time. Because we assume the target density in the foil to be low, this flux will always be uniform over the thickness of the target material. Any incident particle with impact parameter between b and b+db relative to any scattering center will undergo an angular deflection between ? and ? ? d ?, and will scatter into a solid angle d ? . (The larger the impact parameter, the smaller is the scattering angle.) The number of such particles scattered per unit time is 2 ?N 0 b db, since 2 ?b db is the relevant area of the circular ring around each scattering center through which any...
