page_title: LEP Pre-Injector
section_title: History
hierarchical_section_title: LEP Pre-Injector / History
caption_attribution_description: English: Depicted are buildings 2001, 2010 and 2013 on CERN's Meyrin campus. From 1989 until 2001, the buildlings housed the LEP Injector Linac (LIL). Afterwards, it was transformed to the CLIC test facility. The green LIL sign is still visible on the left side of building 2001.
context_page_description: The LEP Pre-Injector was the initial source that provided electrons and positrons to CERN's accelerator complex for the Large Electron–Positron Collider from 1989 until 2000.
  LPI comprised the LEP Injector Linac and the Electron Positron Accumulator.
context_section_description: After groundbreaking for the LEP Collider had taken place in September 1983, the design for its injection scheme, the LEP Pre-Injector (LPI), was finalized in 1984.
  The construction was planned and implemented in close collaboration with Laboratoire de l'accélérateur linéaire (LAL) in Orsay, France. Since there had been no electron/positron accelerators at CERN before, LAL was a valuable source of expertise and experience in this regard.
  The first electron beam with an energy of 80 keV was produced on May 23, 1985.
  LIL injected electrons with an energy of 500 MeV into EPA from July 1986 on, and soon after EPA reached its design intensity. The same was achieved for positrons in April 1987, so the LPI-complex was fully operational in 1987. For the following two years, the accelerating system was further commissioned, threading the electron and positron beams through LIL, EPA, the Proton Synchrotron (PS), the Super Proton Synchrotron (SPS), until finally reaching LEP. The first injection into LEP's ring was achieved on July 14, 1989, one day earlier than originally scheduled. The first collisions were performed on August 13 and the first physics run, allowing LEP's experiments to take data, took place on September 20.
  LPI was serving as a source of electrons and positrons for LEP from 1989 until November 7, 2000, when the last beams were delivered to LEP. Nevertheless, the source continued to operate for other experiments until April 2001 (see section below). After this, work begun to convert LPI facility to be used for the CLIC Test Facility 3 (CTF3), which conducted preliminary research and development for the future Compact Linear Collider (CLIC). The conversion happened in stages, with the first stage (so-called Preliminary Phase) starting accelerator commissioning in September 2001. At the end of 2016, CTF3 stopped its operation. From 2017 on, it was transformed into the CERN Linear Electron Accelerator for Research (CLEAR).
caption: Building of the former LEP Injector Linac (LIL) at CERN, afterwards housing the CLIC test facility. The green LIL sign is still visible on the left side of building 2001.
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