Studies to date at HERA have, for example, demonstrated that the quark and gluon structure of the proton is much more complex and dynamic than previously thought. Thanks to the increased collision rate of HERA, it will now be possible to investigate these structures with a high degree of accuracy at scales 2,000 times smaller than the proton itself. One question that could be tackled is whether particles such as quarks themselves possess a structure. In other words, are they really elementary, as we believe today.

A total of 120 technicians, scientists and engineers worked on the conversion of HERA between September 2000 and mid-May 2001. Altogether, 480 meters of vacuum system had to be replaced, and almost 80 magnets newly designed and fitted, each of which measures between one and four meters and weighs up to seven metric tons. The new magnets will decrease the cross-section of the particle beams immediately before their collision. The beams accelerated by HERA will be focused to one-third of their previous cross-section - from one-hundredth of a square millimeter to just three-thousandths of a square millimeter. This level of precision demanded a sophisticated rearrangement of the two collision zones where the particles meet - already two of the most technically demanding areas in the facility. But it's a good investment, for the probability that the electrons and protons accelerated in HERA will actually collide will be increased considerably. As a result, particle physicists will be able to observe extremely rare processes with a high enough frequency to make their observations statistically valid. However, the flood of uninteresting processes will increase, too. HERA's detectors, which are as large as houses, were therefore also technically improved so that they can more quickly and effectively assess which particle interactions are really interesting.

Recommissioning a high-technology facility such as HERA involves a lot more than just pressing a button. Everything has to fit within a fraction of a millimeter so that the hair-fine particle beams really do meet at the collision points. Their timing too, must be right to within a billionth of a second. After all, what's the use of getting a particle bunch to the collision point, only to find that its counterpart is somewhere else. In the coming months, the HERA team will therefore first "thread" and optimize the individual particle beams in the accelerator, before attempting the first collision. By November, everything should be ready for the next step: slowly increasing the intensity of the beams until the particle collision rate reaches the planned level of four times its previous value. By the beginning of 2002, HERA's should be operating routinely at the new power level.

HERA - the acronym stands for Hadron Electron Ring Accelerator - is the largest particle accelerator at DESY in Hamburg. It has been operating in the service of research since 1992. HERA is the first and only storage ring in which two different types of matter particles - in this case, protons and electrons - collide with one another. Located in a single underground tunnel, HERA consists of two, ring-shaped accelerators, each measuring 6.3 kilometers in circumference. Particle physicists use the facility to investigate the collisions between protons and electrons at two experiments. The electrons act as tiny probes, scanning the interior of the protons, which are much heavier. Two further experiments utilize just one beam each. At each of the collision experiments, around 400 physicists from 50 institutes in 12 countries analyze the tracks left by the colliding particles. Millions of such events take place every second in each of the huge detectors. The objective is clear - to track down the secrets of the proton's interior and to gain more insight into the fundamental forces. HERA - the super electron microscope - will help by providing the world's most penetrating look into the heart of the proton.