The German Electron Synchrotron DESY, Member of the Helmholtz Association, is one of the leading accelerator centers in the world. DESY is a national research center supported by public funds and has locations in Hamburg and Zeuthen (Brandenburg).
Founded in 1959, DESY research center was established in Hamburg, Germany, as an independent foundation under civil war, by means of a treaty signed by the federal minister for atomic energy Siegfried Balke and Hamburg's mayor Max Brauer. More than 1200 phycisists from 25 countries are currently working on the four HERA experiments. A further 2200 guests from 33 countries come to DESY every year in order to conduct experiments in various areas of physics, chemistry, molecular biology, materials science, and medicine at the Hamburg Synchrotron Radiation Laboratory HASYLAB.
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.
1960
The construction of the first particle accelerator DESY (Deutsches Elektronen Synchrotron, "German Electron Synchrotron"), whose name the institute is still bearing, began in 1960. At that time it was the biggest facility of this kind and was able to accelerate electrons to 7.4 GeV. The first measurements with the light beam from the ring accelerator “DESY” started in 1964.
1966
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.
1967
The synchrotron radiation, which comes up as a side effect, was first used in 1967 for absorption measurements.
1969
DORIS (Doppel-Ring-Speicher, "double-ring storage"), built between 1969 and 1974, was DESY's second circular acclerator and its first storage ring with a circumference of nearly 300 m. Constructed as an electron-positron storage ring, one could conduct collision-experiments with electrons and their antiparticles at energies of 3.5 GeV per beam. In 1978 the energy of the beams was risen to 5 GeV each. 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.
1972
The European Molecular Biology Laboratory EMBL made use of the possibilities that arose whith 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.
1975
PETRA (Positron-Elektron-Tandem-Ring-Anlage, "positron-electron tandem-ring facility") was built between 1975 and 1978. At the time of its construction it was the biggest storage ring of its kind and still is DESY's second largest synchrotron after HERA.
1979
The discovery of the gluon, the carrier particle of the strong nuclear force, in 1979 is counted as one of the biggest successes. PETRA can accelerate electrons and positrons to 19 GeV.
1980
The HASYLAB (Hamburger Synchrotronstrahlungslabor, "Hamburg Synchrotron radiation Laboratory") is used for research with synchrotron radiation at DESY. The laboratory adjoins to the storage ring DORIS in order to be able to use the generated synchrotron radiation for its research.
1984
HERA (Hadron-Elektron-Ring-Anlage, "Hadron-Electron-Ring-Facility") is DESY's largest synchrotron and storage ring, with a circumference of 6336 metres.
1985-87
In 1985 the development of more advanced X-ray technology made it possible to bring to light the structure of the influenza virus.
1987-88
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.
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.
1992
The first two experiments started taking data in 1992. HERA is mainly used to study the structure of protons and the properties of quarks.
H1, has been active since 1992, measures 12 m x 10 m x 15 m and weighs 2 800 tons.
ZEUS is like H1 a detector for electron-proton collisions and is located in HERA-Hall South. Built in 1992 it measures 12 m x 11 m x 20 m and weighs 3600 tons.
Its tasks resemble H1's.
1995
The HERMES experiment in HERA-Hall East was taken into operation in 1995. HERA's longitudinally polarised electron beam is used for the exploration of the spin structure of nucleons. For this purpose the electrons are scattered at energies of 27.5 GeV at an internal gas target. This target and the detector itself were designed especially with a view to spinpolarised physics. It measures 3.5 m x 8 m x 5 m and weighs 400 tons.
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.
1997
VUV-FEL (Vacuum-Ultra-Violet Free-Electron-Laser) is a superconducting linear accelerator with a free electron laser for radiation in the vacuum-ultraviolet and soft X-ray range of the spectrum. VUV-FEL is based on the TTF (TESLA Test Facility), which was built in 1997 to test the technology that was to be used in the planned linear collider TESLA, a project which was replaced by the ILC (International Linear Collider). For this purpose the TTF was enlarged from 100 m to 260 m.
1999
HERA-B was an experiment in HERA-Hall West which collected data from 1999 to February 2003. By using HERA's proton beam, researchers at HERA-B conducted experiments on heavy quarks. It measured 8 m x 20 m x 9 m and weighed 1 000 tons.
2004
At the VUV-FEL technology for the future-project XFEL is tested as well as for the ILC.
Particle Accelerators, Facilities and Experiments at DESY
Accelerators at DESY
DESY's accelerators were not built all at once, but rather were added one by one to meet the growing demand of the scientists for higher and higher energies to gain more insight into particle structures. In the course of the construction of new accelerators the older ones were converted to pre-accelerators or to sources for synchrotron radiation for laboratories with new research tasks (for example for HASYLAB).
Nowadays DESY's most important facilities are the acclerator 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. In addition to the larger ones, there are also several smaller particle accelerators which serve mostly as pre-accelerators for PETRA and HERA. Among these are the linear accelerators LINAC I (from 1964 to 1991 for electrons), LINAC II (since 1969 for positrons) and LINAC III (since 1988 as a pre-accelerator for protons for HERA).
Accelerator Experiments
HERA experiments
H1
HERA-B
HERMES
ZEUS
The free-electron laser FLASH (formerly VUV-FEL) generates intense laser light in the soft X-ray range. Many scientific disciplines ranging from physics, chemistry and biology to material sciences, geophysics and medical diagnostics need a powerful X-ray source with pulse lengths in the femtosecond range. This would allow, for example, time-resolved observation of chemical reactions with atomic resolution. Such radiation of extreme intensity, and tunable over a wide range of wavelengths, can be accomplished using high-gain free-electron lasers (FEL).
During the last years a high-gain FEL in the VUV wavelength regime was set up at DESY, Hamburg. It achieves laser amplification and saturation within a single pass of the electron bunch through an undulator and does not require a set of mirrors which is needed in conventional lasers and in the low-gain FEL. The lasing process is initiated by the spontaneous undulator radiation, and the FEL works then in the so-called Self-Amplified Spontaneous Emission (SASE) mode without needing an external input signal.
The electron bunches are produced in a laser-driven photoinjector and accelerated to by a superconducting linear accelerator. At intermediate energies of 125 and 380MeV the 1nC electron bunches are longitudinally compressed, thereby increasing the peak current from initially 50 -80 A to approximately 1-2 kA as required for the FEL operation. The 30 m long undulator consists of NdFeB permanent magnets with a fixed gap of 12 mm, a period length of 27.3 mm and peak magnetic field of 0.47 T. Finally, a dipole magnet deflects the electron beam into a dump, while the FEL radiation propagates to the experimental hall.
Astroparticle Physics
AMANDA & IceCube
The experiments AMANDA and IceCube detect neutrino sources in the cosmos.
Investigations in all fields of natural sciences using a special light generated at accelerators. At DESY’s Hamburg Synchrotron Radiation Laboratory HASYLAB, scientists from various disciplines and researchers from industrial companies carry out experiments using radiation with very special properties, which is generated in particle accelerators. It is extremely intense, tightly collimated and emitted in short pulses. It covers a broad spectrum of electromagnetic radiation ranging from infrared and visible light to ultraviolet radiation and X-rays. This unique kind of light allows physicists, chemists, geologists, biologists, medical and materials researchers to conduct a great variety of experiments.
DESY was thus one of the seed laboratories in which the worldwide success story of research with photons (light particles) began. With its existing and planned light sources, DESY is now one of the foremost facilities for research with the intense radiation generated in accelerators in the world. Experimental stations for such work are available at the storage rings DORIS and PETRA and at the new free-electron laser FLASH (formerly VUV-FEL). In future, DESY will become even more attractive for top researchers from all over the world: And starting in 2013, the European X-ray free-electron laser XFEL will be put into operation.
Photon Research Facilities
XFEL project
DESY is planning the construction of an X-ray laser, the XFEL (X-ray Free-Electron Laser), which is supposed to be 3 km long when finished. It will produce extremely short and powerful X-ray flashes which will have a lot of applications.
In February 2003, the German Federal Ministry of Education and Research gave the green light for the X-ray laser. Together with European partners, the project is to be further developed in such a way that a decision to begin construction can be made at the end of 2004. After a construction period lasting about six years, the commissioning of the facility could start in 2012. An international research team, the TESLA collaboration, is currently trying out the facility's pioneering technology at a test facility in Hamburg, and it has already achieved the key milestones it has been aiming for. The free-electron X-ray laser will make it possible to do leading-edge research in Europe and will guarantee a major role for Germany as a location for research and industry.
The International Linear Collider (ILC)
ILC project team at DESY
International Linear Collider
DESY is involved in the project International Linear Collider (ILC). This project consists of a 20-40 km long linear accelerator. An international consortium decided to build it with the technology originally developed for the TESLA project. There has been no final decision on where to build the accelerator. The ILC will be a high-energy e+e- collider with a centre-of-mass energy reach up to 500 GeV, upgradable to the 1 TeV range. in August 2004, the International Technology Recommendation Panel (ITRP) recommended that ILC should be based on TESLA SCRF technology. The ILC will be designed and constructed by a international collaboration of HEP laboratories and institutes from Europe, the Americas, and Asia.
After an intense eight-month assessment by a group of experts (the International Technology Recommendation Panel ITRP), the International Committee for Future Accelerators ICFA, which represents particle physicists worldwide, decided that the planned linear collider will be realized in superconducting accelerator technology. This technology has been developed jointly by DESY and its international partners – the TESLA Technology Collaboration – and successfully tested at the TESLA test facility in Hamburg.
Synhrotron Radiation
From mid-2007 on, the accelerator PETRA will be converted into a brilliant X-ray radiation source, which is currently used as a pre-accelerator for HERA, shall be reconstructed as a source of synchrotron radiation for HASYLAB.