Content & Structure [Top]

Scope and content

The Large Electron Positron Collider, LEP, is a particle accelerator built inside a circular tunnel 27km round and buried 100 metres underground. At four points around the accelerator, huge detectors called ALEPH (Apparatus for LEp PHysics), DELPHI (DEtector with Lepton, Photon and Hadron Identification), L3 and OPAL (Omni Purpose Apparatus for Lep) studied what happened when electrons and their antimatter counterparts, positrons, collided at high energy.

• ALEPH (Apparatus for LEP pHysics) was a solid-state microstrip detector and the simplest of the detectors : it had a minimum of components and emphasized performance and reliability. It was installed closest to the collision region to give information on very short-lived particles.
• DELPHI (DEtector with Lepton Photon and Hadron Identification), ready in 1989-1990, was a special detector used to identity leptons, photons and hadrons. It incorporates a technology which had never been used on a large scale.
• L3 (which drew its name from being the subject of the third letter of intent for a LEP experiment) was the largest of the detectors and was distinguished by having its magnet on the outside of the detector volume. It aimed for great accuracy in many of its measurements on the particles emerging from the collisions.
• OPAL (Omni-Purpose Apparatus for LEP) was a classic polyvalent detector. Commissioned in 1989, it used tested detector techniques.

LEP was switched on in the summer of 1989. For six years, its job was to produce Z particles, carriers of one of nature's fundamental forces. The Z was first discovered in a Nobel Prize (link is external) winning CERN experiment in 1983. Z particles had been made at LEP when electrons and positrons collided with enough energy to provide their mass, around 91 GeV.

• LEP5 - BREMS : A Single Bremsstrahlung Monitor to Measure Luminosity at LEP
• LEP6 - MODAL : The search for Highly Ionizing Particles in e+e- collisions at LEP using (MODAL) (MOnopole Detector At Lep)

In 1995, LEP's Z era came to an end, the machine moved up a gear to 140 GeV ready for LEP's second phase which pushed the energy to over 190 GeV before the end of the decade. Known as LEP2, this second phase of LEP was to produce and study W particles, companions of the Z, which were also discovered at CERN in 1983.

LEP stopped in November 2000, but the analysis of data is still going on, with the possibility of discovering new physics phenomena.

It was dismantled in 2001 to give way to the Large Hadron Collider LHC.

LEP collection contains minutes of LPC (LEP Project Committee), LMAC ( LEP Machine Advisory Committee), MARTEC (Main Ring Technical Committee), Group Leader's meetings, LEP Management Board (LMB), reports and notes.

Appraisal, destruction and scheduling information

Nothing was destroyed.

Accruals

Further accruals may be received.

System of arrangement

The original order has been preserved. For the purposes of cataloguing the files have been described according to the following plan:

For the purposes of cataloguing the files have been described according to the following plan: