The Hadron Electron Ring Accelerator (HERA) is the first electron-proton collider in the world. HERA was constructed to study high energy scattering between electrons of 30 GeV and protons of 820 GeV. The construction of this two-ring accelerator took from May 1984 until November 1990. The commissioning of the machine proceeded during 1991. The HERA tunnel runs for most of its length of 6.3km outside the site of DESY, near Hamburg in Germany, and 10 m - 25 m deep underground.

There are four experimental halls with sizes of about 25 m x 43 m. The HERA ring tunnel has an inner diameter of 5.2 m The two storage rings for the electron (e) and proton (p) beams are mounted on top of each other. The magnets of the electron storage ring (lower) contain normal conductors and operate at room temperature. The magnets of the proton storage ring (upper) need to produce a magnetic field of 4.7 Tesla for bending the high momentum proton beam in the arcs of the ring.

The HERA collider ring viewed from above

 

Layout of HERA Facility. Click for Larger Image

To accomplish this, superconducting magnets which operate at a temperature of 4.4 K have been constructed. The very high energies offered by HERA permit one to probe deep inside the proton in order to study the structure of its constituents, the quarks and gluons. This effect is known as 'Deep Inelastic Scattering' and effectively uses the electron as a very small wavelength microscope to resolve the size of the elementary particles.