High energy electron scattering

High energy electron scattering by nucleons (protons and neutrons) can reveal the internal structure of these particles. The diffraction of particles depends on their wavelength and so the more energetic the particle the shorter the wavelength and the finer the detail that can be observed. Very high energies are needed to probe the internal structure of a proton or neutron.

At very high energies electrons have a very short wavelength. Of course at such an energy the mass of the electron will be greater than that of the electron at rest and this can be calculated using the special relativity equations.

Using the mass-energy equation: E = mc² and momentum (p) = mv we have:
Momentum (p) = mv = [E/c²]v but at these enormous energies the velocity of the electron is close to that of light and so v =c

Therefore: p = E/c

So the electron wavelength (l) = h/p = hc/E = [6.63x10^-34 x 3x10⁸]/9.6x10^-10 = 2.1x10^-16 m

This wavelength is less than the “diameter” of a nucleon and so these very high energy electrons can be used to probe the “structure” of the proton or neutron.