Skip to main content
Particles and interactions

Particles and interactions

PEP-II shapes up

30 Jul 1998

The PEP-II electron-positron collider at the Stanford Linear Accelerator Center in California collided particles for the first time last week. When completed in the Autumn, PEP-II will produce large numbers of bottom quarks which physicists will use to probe the difference between matter and anti-matter.

PEP-II consists of two independent storage rings in the tunnel that housed the original PEP collider. The high-energy ring, which stores a 9 GeV electron beam, is an upgrade of the existing PEP collider, while the low-energy ring, in which the 3.1 GeV positrons are stored, is completely new.

Matter and anti-matter are thought to have been created in equal amounts in the Big Bang, and should have completely annihilated each other. However, we clearly live in a matter-dominated universe, which indicates that a small imbalance must have existed between matter and anti-matter at a very early stage in the universe. PEP-II will make measurements which, physicists hope, will clarify some of the competing theoretical models for this mechanism.

Related events

Copyright © 2024 by IOP Publishing Ltd and individual contributors