DESY:On the trail of elementary particles

Tiny particles that are accelerated to almost the speed of light and then made to collide. Super-brilliant flashes of light that researchers can use to look down into the molecular structure of matter. For many, the processes that take place on the DESY research site in Hamburg-Bahrenfeld are difficult to imagine. The facility with its accelerator tubes, which was founded on December 18, 1959, is now one of the world's most important facilities for researching matter. At DESY, scientists from all over the world look for the basic building blocks of the world, decode protein molecules or analyze materials with completely new properties.

It was the starting signal for one of the world's most important institutions for research into the smallest particles:On December 18, 1959, the then Mayor of Hamburg Max Brauer and the Federal Minister for Nuclear Energy and Water Management, Siegfried Balke, signed a state treaty in Hamburg City Hall to found the "German Electron Synchrotron Foundation", abbreviated to DESY. The project is groundbreaking - at that time particle accelerators were only available in a few countries, including the USA. The system is expected to cost 100 million Deutschmarks, 90 percent of which will be borne by the Federal Ministry and ten percent by the City of Hamburg.

In search of the smallest particles

But why all the effort? Researchers had discovered that there are far more of the tiny building blocks of matter than previously thought. One speaks of a whole "particle zoo". From the end of the 1950s, researchers in Germany wanted to search for the smallest building blocks of matter. The facility is to be built in Hamburg-Bahrenfeld - on a site that was used as a parade ground and military airport in the past.

1964:Research in the "particle zoo" begins

It will take more than four years for the huge facility to be operational. On February 25, 1964, shortly before midnight, the time had finally come:a handful of physicists crowded into the control room of the new particle accelerator. The researchers press the decisive switch - and shortly afterwards can celebrate:the first stream of electrons whizzes around 8,000 times through the accelerator's circular vacuum tube. DESY will officially go into operation soon. The electrons race through the tube at almost the speed of light, large electromagnets keep them in their orbit. Researchers let the electrons collide head-on when they have absorbed enough energy. The collision creates short-lived particles, tiny building blocks of matter. Detectors make them visible to researchers.

Further accelerators will follow DESY

The accelerator DESY, which still gives the entire research facility its name, is only the beginning. More accelerators were built over the decades - they are called DORIS, PETRA or HERA, at 3.6 kilometers the longest accelerator ring on the site. Today, the development, construction and operation of particle accelerators is one of the three main research areas at DESY, alongside particle physics and research with photons.

The gluon - discovered at DESY

Particle physics, which deals with the question of the inner structure of matter, is the oldest of the three research areas. The researchers achieved particular success in this field in 1979:At PETRA, the scientists were able to detect the gluon for the first time - probably the best-known discovery made at DESY to date. The gluon is the carrier particle of the so-called strong force. It is one of the four fundamental natural forces, along with gravity, electromagnetic force and the so-called weak force. Figuratively speaking, the gluon is a kind of glue that holds the particles of matter together.

Explore the nanoworld with flashes of light

A third focus at DESY today is research with photons, i.e. light particles. If electrons are strongly accelerated, they emit part of their energy as an intense beam of light. Scientists can use this so-called synchrotron radiation to gain insights into the nanoworld and, for example, to examine molecular structures. Or also to "illuminate" a wide variety of materials. In 2008, for example, a Van Gogh painting that had been painted over was made visible again using synchrotron radiation from the DORIS accelerator - a research success that was also widely reported in the media.

PETRA is now also used as an X-ray source. Since 2009, scientists have been using PETRA III to generate radiation in the range of hard, very short-wave X-rays. This light is very intense, sharply focused and flashes in short pulses. Researchers can use it to examine very small samples. Biologists use it, for example, to research the atomic structure of protein crystals.

FLASH - ultra-short flashes of light

With the free electron laser FLASH, a linear accelerator has also been in operation on the DESY site since 2005 - the first in the world to generate flashes of light in the extreme ultraviolet range up to soft, i.e. relatively long-wave X-rays.

Instead of circling, the particles in the 300-meter-long, dead-straight facility are brought almost to the speed of light by a superconducting accelerator and guided through "undulators" - structures made up of hundreds of pairs of magnets that force the electrons on a slalom course. The particles emit ultra-short, strong flashes of light. Among other things, they can be used to track processes that run extremely quickly, such as chemical reactions.

Both the measuring stations in the FLASH experimental hall and at PETRA are in great demand - only a small part of the worldwide inquiries from research institutions and companies can be served. The system is therefore to be expanded from 2020 to the new FLASH2020 system.

European XFEL:The world's longest X-ray laser

The European X-ray free-electron laser European XFEL, which began scientific operation in 2017, is based on the same principle as FLASH. It is the youngest facility at DESY and the world's largest X-ray laser.

With the help of its X-ray flashes, researchers can decode atomic details of viruses and cells, film chemical reactions and take three-dimensional images of the nanocosm, i.e. the world of cells and molecules. The 3.4-kilometer linear accelerator tube runs underground from the DESY site to behind the state border with Schleswig-Holstein and ends there in an experimental hall. Twelve countries are involved in financing the facility, which costs around 1.2 billion euros, with Germany and Russia being the largest donors.

On the trail of the Higgs particle

But particle physics continues to be of great importance for DESY. The Hamburg-based company is involved in research on the Large Hadron Collider LHC, a gigantic ring accelerator with a circumference of 27 kilometers at the CERN research center in Geneva. It was there that researchers discovered the long-sought Higgs particle in 2012. DESY is also involved in the future project International Linear Collider ILC, a linear accelerator which, among other things, is intended to examine the Higgs particle more closely. However, the final decision as to whether this project will be implemented is still pending.

Ghost particles in the eternal ice

Another spectacular project in which DESY is involved is called Icecube:researchers have inserted more than 5,000 detectors up to 2,450 meters deep into the eternal ice of Antarctica. They serve as a huge telescope to detect so-called neutrinos. These extremely light particles usually fly through all matter unhindered and are therefore also called ghost particles. Only very rarely do they collide with matter particles and can be observed in this way. In the Antarctic, researchers are looking for neutrinos that do not come from our solar system, but rather from black holes or supernova explosions. They can shed light on these powerful cosmic events. Twice - in 2012 and again in 2013 - the researchers were able to detect these high-energy neutrinos in the depths of space.

Research center of global importance

With its three research areas, DESY is now one of the world's most important centers for research into the structure and function of matter. Around 3,000 guest scientists from around 40 nations research the microcosm in all its diversity with the help of the accelerators. Among other things, they test the behavior of novel nanomaterials or observe the course of vital processes between molecules and thus provide important insights for the development of drugs and new technologies.