Deep inelastic scattering is the name given to a process used to probe the insides of hadrons (particularly the baryons, such as protons and neutrons), using electrons, muons and neutrinos. It provided the first convincing evidence of the reality of quarks, which up until that point had been considered by many to be a purely mathematical phenomenon. It is a relatively new process, first attempted in the 1960s and 1970s. It is an extension of Rutherford scattering

Rutherford scattering

In physics, Rutherford scattering is a phenomenon that was explained by Ernest Rutherford in 1911, and led to the development of the Rutherford model of the atom, and eventually to the Bohr model. It is now exploited by the materials analytical technique Rutherford backscattering...

 to much higher energies of the scattering particle and thus to much smaller resolution of the components of the nuclei.

Quarks

The Standard Model

Standard Model

The Standard Model of particle physics is a theory concerning the electromagnetic, weak, and strong nuclear interactions, which mediate the dynamics of the known subatomic particles. Developed throughout the mid to late 20th century, the current formulation was finalized in the mid 1970s upon...

 of physics, particularly given the work of Murray Gell-Mann

Murray Gell-Mann

Murray Gell-Mann is an American physicist and linguist who received the 1969 Nobel Prize in physics for his work on the theory of elementary particles...

 in the 1960s, had been successful in uniting much of the previously disparate concepts in particle physics

Particle physics

Particle physics is a branch of physics that studies the existence and interactions of particles that are the constituents of what is usually referred to as matter or radiation. In current understanding, particles are excitations of quantum fields and interact following their dynamics...

 into one, relatively straightforward, scheme. In essence, there were three types of particles.

• The leptons, which were light (as in not particularly massive) particles such as electrons, neutrinos and their antiparticles. They have integer charge
• The bosons, which were particles that exchange forces. These ranged from the massless, easy-to-detect photon
  Photon
  In physics, a photon is an elementary particle, the quantum of the electromagnetic interaction and the basic unit of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force...
  
   (the carrier of the electro-magnetic force) to the exotic (though still massless) gluons that carry the strong nuclear force
• The quarks, which were massive particles that carried fractional charges. They are the "building blocks" of the hadrons. They are also the only particles to be affected by the strong interaction
  Strong interaction
  In particle physics, the strong interaction is one of the four fundamental interactions of nature, the others being electromagnetism, the weak interaction and gravitation. As with the other fundamental interactions, it is a non-contact force...
  
  

The leptons had been detected since 1897, when J. J. Thomson

J. J. Thomson

Sir Joseph John "J. J." Thomson, OM, FRS was a British physicist and Nobel laureate. He is credited for the discovery of the electron and of isotopes, and the invention of the mass spectrometer...

 had shown that electric current

Electric current

Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...

 is a flow of electrons. Some bosons were being routinely detected, although the W⁺, W^- and Z⁰ particles of the electroweak force were only categorically seen in the early 1980s, and gluons were only firmly pinned down at DESY

DESY

The DESY is the biggest German research center for particle physics, with sites in Hamburg and Zeuthen....

 in Hamburg

Hamburg

-History:The first historic name for the city was, according to Claudius Ptolemy's reports, Treva.But the city takes its modern name, Hamburg, from the first permanent building on the site, a castle whose construction was ordered by the Emperor Charlemagne in AD 808...

at about the same time. Quarks, however, were still elusive.