The Super Proton Synchrotron is a particle accelerator of the synchrotron type at CERN. It is housed in a circular tunnel, 6.9 km in circumference, straddling the border of France and Switzerland near
Test beamline delivered from the SPS. In photo 20 GeV positrons are used to calibrate the Alpha Magnetic Spectrometer.
Aerial view of the 28 GeV Proton Synchrotron. The underground ring of the 28 GeV proton synchrotron in 1965. Left, the South and North experimental halls. Top right, part of the East hall. Bottom right, the main generator room and the cooling condensers.