DESY's main purposes are fundamental research in particle physics and research with synchrotron radiation. For this DESY develops and runs several particle accelerators. DESY is financed by the public authorities and is a member of the Helmholtz Association of National Research Centres.
DESY's function is scientific fundamental research with an emphasis on the following three topics:
At the site in Hamburg most of DESY's research in high energy physics with elementary particles has been taking place since 1960. Besides the already running accelerators there is also a free electron laser called XFEL being developed. This project is meant to secure DESY's future place among the top research centers of the world.
DESY Zeuthen is currently contributing to the experiments at HERA in Hamburg for example by evaluating data. It is also collaborating with DESY Hamburg in the development of the XFEL.
Zeuthen is also participating in two in the context of DESY’s research rather unusual projects:
The experiments at the accelarators are financed by the participating German and foreign institutes, which in turn are often financed by means of public funding.
(date: January 2005)
Included in theses numbers are 100 apprentices as well as the 100 diploma students, 430 graduate students and 240 junior scientists who are supervised by DESY.
Following the example of HERA, many scientific projects of a large scale are financed jointly by several states. By now this model is established and international cooperation is pretty common with the construction of those facilities.
Nowadays DESY's most important facilities are the accelerator HERA, the synchrotron-research lab HASYLAB and the free-electron laser VUV-FEL, the test facility for the planned XFEL. The development of the different facilities will be described chronologically in the following section.
The international attention first focused on DESY in 1966 due to its contribution to the validation of quantum electrodynamics, which was achieved with results from the accelerator. In the following decade DESY established itself as a center of excellence for the development and operation of high-energy accelerators.
The synchrotron radiation, which comes up as a side effect, was first used in 1967 for absorption measurements. For the arising spectrum there had not been any conventional radiation sources beforehand. The European Molecular Biology Laboratory EMBL made use of the possibilities that arose with the new technology and in 1972 established a permanent branch at DESY with the aim of analyzing the structure of biological molecules by means of synchrotron radiation.
The electron-synchrotron DESY II and the proton-synchrotron DESY III were taken into operation in 1987 and 1988 respectively as pre-accelerators for HERA.
With evidence of the "excited charmonium states" DORIS made an important contribution to the process of proving the existence of heavy quarks. In the same year there were the first tests of X-ray lithography at DESY, a procedure which was later refined to X-ray depth lithography.
In 1987 the ARGUS detector of the DORIS storage ring was the first place where the conversion of a B-meson into its antiparticle, the anti-B-meson was observed. From this one could conclude that it was possible, for the second-heaviest quark - the bottom-quark - under certain circumstances to convert into a different quark. One could also conclude from this that the unknown sixth quark - the top quark - had to possess a huge mass. The top quark was found eventually in 1995 at the Fermilab in the USA.
After the commissioning of HASYLAB in 1980 the synchrotron radiation, which was generated at DORIS as a byproduct, was used for research there. While in the beginning DORIS was used only ⅓ of the time as a radiation source, from 1993 on the storage-ring solely served that purpose under the name DORIS III. In order to achieve more intense and controllable radiation, DORIS was upgraded in 1984 with wigglers and undulators. By means of a special array of magnets the accelerated electrons could now be brought onto a slalom course. By this the intensity of the emitted synchrotron radiation was increased a hundredfold in comparison to conventional storage ring systems.
DORIS III provides 42 experimental areas, where ca. 80 instruments are operated in circulation. The overall beam time per year amounts to 8 to 10 months.
Research at PETRA lead to an intensified international use of the facilities at DESY. Scientists from China, England, France, Israel, the Netherlands, Norway and the USA participated in the first experiments at PETRA alongside many German colleagues.
In 1990 the facility was taken into operation under the name PETRA II as a pre-accelerator for protons and electrons/positrons for the new particle accelerator HERA. In March 1995, PETRA II was equipped with undulators to create greater amounts of synchrotron radiation with higher energies, especially in the X-ray part of the spectrum. Since then PETRA serves HASYLAB as a source of high-energy synchrotron radiation and for this purpose possesses three test experimental areas. Positrons are accelerated to up to 12 GeV nowadays.
After the upgrade of DORIS with the first wigglers, which produced far more intense radiation, the first Moessbauer spectrum acquired by means of synchrotron radiation was recorded at HASYLAB in 1984.
In 1985 the development of more advanced X-ray technology made it possible to bring to light the structure of the influenza virus. In the following year researchers at HASYLAB were the first to successfully make the attempt of exciting singular grid oscillations in solid bodies. Thus it was possible to conduct analyses of elastic materials, which were possible prior to this only with nuclear reactors via neutron scattering.
In 1987 the workgroup for structural molecular biology of the Max Planck Society founded a permanent branch at HASYLAB. It uses synchrotron radiation to study the structure of ribosomes.
Nowadays many national and foreign groups of researchers conduct their experiments at HASYLAB: All in all 1900 scientists participate in the work. On the whole the spectrum of the research ranges from fundamental research to experiments in physics, material science, chemistry, molecular biology, geology and medicine to industrial cooperations.
One example is OSRAM, which since recently uses HASYLAB to study the filaments of their light bulbs. The gained insights helped to notably increase the life span of the lamps in certain fields of application.
In addition researchers at HASYLAB analysed among other things minuscule impurities in silicone for computer chips, the way catalysators work, the microscopic properties of materials and the structure of protein molecules.
HERA (Hadron-Elektron-Ring-Anlage, "Hadron-Electron-Ring-Facility") was DESY's largest synchrotron and storage ring, with a circumference of 6336 metres. The construction of the subterranean facility began in 1984, and HERA began operation on November 8, 1990. The first two experiments started taking data in 1992. HERA is mainly used to study the structure of protons and the properties of quarks. HERA's construction was an international task: In addition to Germany 11 further countries participated in the development of the accelerator. HERA was closed down June 30th in 2007 .
HERA was the first and only accelerator in the world that was able to collide protons with either electrons or positrons. To make this possible HERA used mainly superconducting magnets, which was also a world first. At HERA it was possible to study the structure of protons up to 30 times more accurately than before. The resolution covered structures 1/1000 of the proton in size. In the years to come there were made a lot of discoveries concerning the composition of protons from quarks and gluons.
HERA's tunnels run 10 to 25 metres below ground level and have an inner diameter of 5.2 metres. For the construction the same technology was used as for the construction of subway tunnels. Two circular particle accelerators run inside the tube. One accelerated electrons to energies of 27.5 GeV the other one protons to energies of 920 GeV in the opposite direction. Both beams completed their circle nearly at the speed of light, making approximately 47 000 revolutions per second.
At two places of the ring the electron and the proton beam could be brought to collision. In the process electrons or positrons are scattered at the constituents of the protons, the quarks. The products of these particle collisions, the scattered lepton and the quarks, which are produced by the fragmentation of the proton, were registered in huge detectors. In addition to the two collision zones there are two more interaction zones. All four zones are placed in big subterraneous halls. A different international group of researchers were at work in each hall. These groups developed, constructed and run house-high, complex measurement devices in many years of cooperative work and evaluate enormous amounts of data.
The experiments in the four halls will be presented in the following section:
It was designed for the decryption of the inner structure of the proton, the exploration of the strong interaction as well as the search for new kinds of matter and unexpected phenomena in particle physics.
Its tasks resemble H1's.
At the VUV-FEL technology for the future-project XFEL is tested as well as for the ILC. Five test experimental areas have been in use since the commissioning of the facility in 2004.
A European project in collaboration with DESY is planning the construction of an X-ray laser, the European x-ray free electron laser (XFEL), which is supposed to be 3 km long when finished. It will produce extremely short and powerful X-ray flashes which will have many applications.
Furthermore the accelerator PETRA, which was used as a pre-accelerator for HERA, is being reconstructed to be a source of synchrotron radiation for HASYLAB. The PETRA III synchrotron will take up user operation in 2009.