Deep inelastic scattering

Source: Wikipedia, the free encyclopedia.
perturbative expansion. The virtual photon
(γ*) knocks a quark (q) out of the hadron.

In

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

Henry Way Kendall, Jerome Isaac Friedman and Richard E. Taylor were joint recipients of the Nobel Prize of 1990 "for their pioneering investigations concerning deep inelastic scattering of electrons on protons and bound neutrons, which have been of essential importance for the development of the quark model in particle physics."[3]

Description

To explain each part of the terminology, "

quark confinement, the quarks are not actually observed but instead produce the observable particles by hadronization. "Deep" refers to the high energy of the lepton, which gives it a very short wavelength and hence the ability to probe distances that are small compared with the size of the target hadron, so it can probe "deep inside" the hadron. Also, note that in the perturbative approximation it is a high-energy virtual photon
emitted from the lepton and absorbed by the target hadron which transfers energy to one of its constituent quarks, as in the adjacent diagram.

Povh and Rosina pointed out that the term “deep inelastic scattering against nucleons” was coined when the quark substructure of nucleons was unknown. They prefer the term “quasielastic lepton-quark scattering”.

History

See also: Quark § History

The Standard Model of physics, in particular the work of Murray Gell-Mann in the 1960s, had been successful in uniting much of the previously disparate concepts in particle physics into one, relatively straightforward, scheme. In essence, there were three types of particles:

The leptons had been detected since 1897, when

electroweak force were only categorically seen in the early 1980s, and gluons were only firmly pinned down at DESY in Hamburg
at about the same time. Quarks, however, were still elusive.

Drawing on

alpha particles
at atoms of gold. Most had gone through with little or no deviation, but a few were deflected through large angles or came right back. This suggested that atoms had internal structure and a lot of empty space.

In order to probe the interiors of baryons, a small, penetrating and easily produced particle needed to be used. Electrons were ideal for the role, as they are abundant and easily accelerated to high energies due to their electric charge. In 1968, at the

neutrinos, but the same principles apply.[1][7]

The collision absorbs some kinetic energy, and as such it is inelastic. This is a contrast to Rutherford scattering, which is elastic: no loss of kinetic energy. The electron emerges from the nucleus, and its trajectory and velocity can be detected. Analysis of the results led to the conclusion that hadrons do indeed have internal structure. The experiments were important because not only did they confirm the physical reality of quarks, but also proved again that the Standard Model was the correct avenue of research for particle physicists to pursue.

See also

References

  1. ^
    ISBN 9780198506713
    .
  2. ^
    doi:10.3204/DESY-PROC-2012-02/6
    .
  3. ^ "Nobel prize citation". Nobelprize.org. Retrieved 2011-01-08.
  4. ^ E. D. Bloom; et al. (1969). "High-Energy Inelastic e–p Scattering at 6° and 10°".
    doi:10.1103/PhysRevLett.23.930
    .
  5. ^
    S2CID 2575595
    .
  6. Hue University. Archived from the original
    on 2008-12-25. Retrieved 2012-02-25.
  7. arXiv:2212.05616 [hep-ph
    ].

Further reading
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