PETRA

PETRA was an electron–positron storage ring at DESY in Hamburg, Germany, operating from 1978 to 1986. Its experiments provided evidence for gluons, the carriers of the strong force.

Electron–positron annihilation: A process in which an electron and positron convert their energy into other particles, often photons. Collisions in PETRA produced particle showers through electron–positron annihilation.
Gluon: The massless gauge boson that mediates the strong interaction between quarks. Three-jet events at PETRA provided compelling evidence for the gluon.
DESY: A German research center for particle physics and photon science, based in Hamburg and Zeuthen. DESY designed and operated PETRA as part of its accelerator research program.
TASSO experiment: A particle-physics experiment at PETRA that studied high-energy electron–positron collisions. TASSO reported prominent evidence for gluon jets from PETRA data.
Particle detector: An instrument that measures properties of particles produced in physical processes. PETRA experiments inferred collision products from tracks and energy deposits recorded by detectors.
Three-jet event: A collider event in which particles form three distinct sprays, or jets. PETRA experiments observed three-jet patterns consistent with gluon radiation.
DORIS: An electron–positron storage ring at DESY that operated before PETRA. DORIS preceded PETRA and provided experience with electron–positron storage rings.
MARK-J experiment: A particle-physics experiment at PETRA, known for studies of jets and event shapes. MARK-J measurements helped characterize the three-jet topology at PETRA.
Collider: A particle accelerator that brings two beams into collision to study their interactions. PETRA was a collider, with counter-rotating beams meeting at experimental stations.
Quantum chromodynamics: The quantum field theory describing the strong interaction among quarks and gluons. PETRA's event shapes tested predictions of quantum chromodynamics at high energies.

Linked from 9 pages