Positron-Electron Project

collider

Also known as: PEP

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July 1, 2026

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The Positron-Electron Project (PEP) was a collider at SLAC that began operation in 1980. It was designed to collide electrons and positrons at high energies, reaching a total of 30 GeV. This allowed scientists to study fundamental particles and their interactions. PEP was a significant advancement in particle physics research, contributing to our understanding of matter and antimatter. The facility was later repurposed for synchrotron-radiation research, providing intense X-ray beams for various scientific studies.1

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particle accelerator
Electron storage rings
In the PEP-II storage rings at Stanford University and in the KEK-B facility at the National Laboratory for High Energy Physics (KEK) in Tsukuba, electrons and positrons are stored at different energies so that they have different values of momentum. When they annihilate, the net momentum is…
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In the PEP-II storage rings at Stanford University and in the KEK-B facility at the National Laboratory for High Energy Physics (KEK) in Tsukuba, electrons and positrons are stored at different energies so that they have different values of momentum. When they annihilate, the net momentum is…
Read More

SLAC
…higher-energy colliding-beam particle accelerator, the Positron-Electron Project (PEP), which began operation in 1980 and raised electron-positron collision energies to a total of 30 GeV. As the high-energy physics program at SLAC was shifted to PEP, the SPEAR particle accelerator became a dedicated facility for synchrotron-radiation research. SPEAR now provides high-intensity…
Read More
…higher-energy colliding-beam particle accelerator, the Positron-Electron Project (PEP), which began operation in 1980 and raised electron-positron collision energies to a total of 30 GeV. As the high-energy physics program at SLAC was shifted to PEP, the SPEAR particle accelerator became a dedicated facility for synchrotron-radiation research. SPEAR now provides high-intensity…
Read More