Deep inelastic scattering (DIS) is a powerful experimental technique used to investigate the internal structure of nucleons (protons and neutrons). In these experiments, high-energy electrons or other leptons are fired at nucleons, and the way they scatter provides detailed information about what’s inside.
Key features of DIS:
- At high energies, the wavelength of the probing particle becomes short enough to resolve individual constituents within the nucleon.
- Instead of bouncing off the nucleon as a whole (elastic scattering), the incoming particle strikes a parton—a quark or gluon—inside the nucleon, transferring significant energy and breaking the nucleon apart.
- The scattering patterns and energy distributions of the resulting particles reveal the momentum and spatial distributions of quarks and gluons.
Major discoveries from DIS include:
- Evidence for quarks as real constituents of protons and neutrons.
- The discovery of sea quarks and gluons, showing that nucleons are more than just three valence quarks.
- Confirmation of the parton model and support for quantum chromodynamics (QCD).
Deep inelastic scattering experiments, such as those at SLAC in the 1960s and at CERN and DESY later, revolutionized particle physics and helped establish the Standard Model. They continue to be an essential tool for exploring the structure of matter at the smallest scales.