High Energy Particle Collisions (Edexcel International A Level Physics)

High Energy Particle Collisions

The Diameter of a Nucleon

• High energy electron beams can be used to analyse nucleons, e.g.

  • Protons

  • Neutrons

• When electrons are accelerated to very high energies, they can collide with nucleon targets

• The scattering pattern is used to analyse the size and structure of nucleons

• To resolve detail, like the nucleon diameter, the de Broglie wavelength of the electron must be comparable to the size of the nucleon 

  • The de Broglie wavelength, and hence an approximation to nucleon diameter, is given by:

≈ nucleon diameter

• Where:

  • λ = de Broglie wavelength (m)

  • h = Planck's constant (J s)

  • m = mass (kg)

  • v = velocity (m s^–1)

• Note that electrons do not experience the strong nuclear force

  • Therefore, they are able to get extremely close to the nucleons without interacting 

  • This allows them to build up a better idea about the size of the nucleus than alpha particles, which are comprised of protons and neutrons

Inside the Nucleon

• If electrons are accelerated to even higher energies, their de Broglie wavelength becomes even smaller

  • This is because therefore the faster the electrons, the smaller their de Broglie wavelength

• Hence, the electron wavelength becomes small enough to be used to resolve internal structure of the nucleon

  • Such an electron beam would be able to resolve individual quarks inside the nucleon