The Super Proton Synchrotron (SPS) is a 6.9 km long particle accelerator at CERN. Originally specified as a 300 GeV proton machine, the SPS was actually built to be capable of 400GeV, an operating energy it achieved on the official commissioning date of 17 June 1976. However, by that time this energy had been exceeded by Fermilab, who reached an energy of 500 GeV on May 14 of that year.

The SPS was designed by a team led by Sir John Adams KBE FRS, CERN director-general of what was then known as Laboratory II,

The SPS has been used to accelerate antiprotons, electrons and positrons (for use as the injector for CERN's LEP electron-positron collider) and heavy ions.And, most notably as a proton-antiproton collider (as such it was called $Spbar\{p\}S$) from 1981 to 1984, when its beams provided the data for the UA1 and UA2 experiments, which resulted in the discovery of the W and Z bosons, earning a Nobel Prize for Carlo Rubbia and Simon van der Meer in 1984.

The SPS is now used as the final pre-injector for high-intensity proton beams for CERN's Large Hadron Collider, which began preliminary operation on 10 September 2008, accelerating protons from 26GeV to 450GeV. Operation as pre-injector will still allow continuation of the ongoing fixed target research program, where the SPS is used to provide 400 GeV protons beams for a number of active fixed-target experiments, notably COMPASS and NA48.The SPS will also be used to produce a neutrino stream to be detected at the Italian Gran Sasso laboratory, 730 km from CERN.

The SPS has served as an ideal testbench for the new concepts in accelerator physics. In 1999 it served as an observatory for the electron cloud phenomenon. In 2003, SPS was the first machine where the Hamiltonian resonance driving terms were directly measured. And in 2004, experiments to cancel the detrimental effects of beam encounters (like those in the LHC) were carried out.

SPS upgrade: The Super-SPS

It has been proposed that the Large Hadron Collider will require an upgrade, to considerably increase its luminosity, by 2015. This would require upgrades to the entire pre-injector chain, including the SPS. The improvements to the SPS would most likely focus on increasing the extraction energy of the Super-SPS up to 1 TeV .

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