Sharp eye into the ultra-fast
Press Release of March 15, 2017
|The Terahertz-facility TELBE is, because of its high-repetition-rate, an important test facility for scientists from all over the world for the development of diagnostics and fast data aquisition schemes for the next generation of X-ray free-electron lasers.|
|Source: HZDR/F. Bierstedt|
Researchers from HZDR, DESY, SLAC and the Fritz-Haber-Institute demonstrate the opportunities of arrival time and intensity binning at unprecedented repetition rates at the quasi-cw SRF linac driven THz facility TELBE.
Many technological processes for example in information technology occur on very short timescales of the order of one picosecond or less. Scientists use the term ultra-fast when referring to techniques that allow monitoring dynamics on these timescales by means of stroboscopic movies based on pump-probe techniques. Researchers from the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) in Dresden, together with colleagues from Hamburg, Berlin and California now demonstrate how this type of movies can be taken with an exceptional dynamic range at superconducting radiofrequency (SRF) accelerator-based light sources. The technique is based on the precise pulse-resolved measurement and correction of the arrival time and intensity fluctuations of the accelerator-based photon pulses at repetition rates of presently up to 100 kHz quasi-cw.
The technological advance makes it meanwhile possible to film important processes in the materials and life sciences in order to understand their underlying principles. The relevant timescales are often in the femtosecond regime and the actual making of a high-speed movie still poses a challenge. As a comparison: it takes a light pulse only 1 second to travel the 380 000 kilometers from earth to moon, while within 1 femtosecond light merely travels the distance equivalent to the diameter of human hair.
To make these high-speed movies, researchers use lasers and increasingly also accelerator-based light sources such as free-electron lasers in order to generate the required ultra-short light pulses. One of these facilities is the new THz facility “TELBE” at the quasi-cw SRF accelerator ELBE. TELBE is a prototype light source that allows generating, in this specific case, intense THz light pulses at particularly high duty cycle.
The drawback of accelerator-based light sources such as TELBE in Dresden or the X-ray free-electron laser XFEL in Hamburg is that the intensity and arrival time of the light pulses fluctuates. Thereby many of the dreamed of experiments are difficult or impossible to realize. The recent work, published in the open access journal “Structural Dynamics” now demonstrates that these fluctuations and instabilities can be measured and can be corrected for in a way that enables achieving unprecedented data quality.
The scheme, developed within the frame of the European project cluster EUCALL, presently enables a time resolution of 30 fs. However, further improvements are within reach, as the researchers describe. The work was performed within a collaboration between HZDR scientists and researchers from the Deutsche Elektronen Synchrotron (DESY) in Hamburg, the Fritz-Haber-Institute in Berlin and the SLAC National Accelerator Laboratory in Menlo Park/USA.
Information on the EUCALL-project
The European Cluster of Advanced Laser Light Sources (EUCALL) is a network between leading large-scale user facilities for free-electron lasers, synchrotron and optical laser radiation and their users. Under EUCALL, they work together on their common methodologies and research opportunities, and develop tools to sustain this interaction in the future. EUCALL has received funding from the European Union’s Horizon 2020 research and innovation programme and involves eleven partners from nine countries as well as the networks Laserlab Europe and FELs of Europe during the project period 2015 to 2018.
S. Kovalev, B. Green, T. Golz, S. Maehrlein, N. Stojanovic, A. S. Fisher, T. Kampfrath, M. Gensch: Probing ultra-fast processes with high dynamic range at 4th-generation light sources: Arrival time and intensity binning at unprecedented repetition rates, in Structural Dynamics, 2017, 4, pp 10159–10165 (DOI: 10.1063/1.4978042)
Dr. Michael Gensch
Institute of Radiation Physics at HZDR
Phone: +49 351 260-2464
Simon Schmitt | Science editor
Phone: +49 351 260-3400 | Mail: email@example.com