PETRA III Speeds 1st Beam

The new synchrotron radiation source PETRA III accelerated its first beam Thursday, according to DESY, the largest research center for particle physics in Germany.

At 10:14 a.m. local time, the positron bunches were injected and stored in the 2.3-km accelerator for the first time, concluding the two-year conversion of the PETRA storage ring into the PETRA III, the most brilliant storage-ring-based x-ray source in the world, officials said.

The 5.8-ton PETRA III undulator is lifted into its place. All beamlines are being equipped with so-called undulators: long magnet arrangements delivering x-ray radiation with especially high brilliance. High brilliance means that a large number of photons are concentrated into a very small area and form an extremely intense light beam. (Images: DESY Hamburg)

Until July 2007, PETRA was mainly used as a pre-accelerator for HERA, DESY’s largest particle accelerator. The accelerator was originally built for particle physics; the gluon, a carrier particle for one of the four fundamental forces in the world, the strong force, was discovered at PETRA.

In future operations, up to 960 particle bunches containing up to 10 billion positrons – the antiparticles to electrons – will circle the storage ring around the clock at almost the speed of light, generating particularly highly energetic radiation of more than 100 keV with high brilliance – a decisive advantage for many experiments.

“With PETRA III, DESY is commissioning another x-ray light source for research, a facility without comparison worldwide,” said professor Helmut Dosch, chair of the DESY board of directors. “With this light source, we will offer the most brilliant synchrotron radiation to our users, setting new standards in photon science.”

As the most powerful light source of its kind, PETRA III will be of particular value to those who investigate very small samples or require tightly focused and very short-wavelength x-rays for their experiments, officials said. For example, structural biologists will be able to reveal the spatial atomic structure of tiny protein crystals – information needed for genetic research, or to develop drugs targeted for specific locations in the body.

The brilliant new x-ray source will also offer a wide range of possibilities in materials research, where scientists require particularly energetic photons with large penetrating power for applications such as examining welding seams or studying structural fatigue. For some applications, materials scientists require particularly energetic photons with large penetrating power, for instance to examine welding seams or to study fatigue of workpieces.

Electromagnetic fields accelerate the electrons in a superconducting resonator.

“Our DESY team has shown that even today it is possible to complete a complex project like the PETRA III upgrade within the determined time frame and budget – even in today’s times,” said professor Edgar Weckert, DESY research director for photon science.

Under the €225 million (about $293 million) upgrade, largely funded by the German government, a 300-m-long experimental hall was built over one-eighth of the PETRA ring, housing 14 synchrotron beamlines and up to 30 experimental stations.

To ensure that the high-precision measuring equipment in the experiments is not affected by vibration, the experiments are being installed on the largest monolithic concrete slab in the world.

After the stable storage of the particle beam achieved Thursday, the accelerator will be set up for the production of the most desired synchrotron radiation in the coming weeks. The undulators – special magnets producing synchrotron radiation – will be positioned close to the particle beam, making the positrons follow a zigzag course to make them emit synchrotron radiation.

A first test run with synchrotron radiation is planned this summer; regular user operation will start in 2010.

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