The first measuring period for external users at the vacuum ultraviolet free-electron laser (VUV-FEL), the new ultraviolet and X-ray radiation source at DESY, ended successfully on 27 February. Now the facility is gearing up for its second run in May.
The facility’s centre-piece is the 300 m long FEL, which is the world’s first – and until 2009, only – source of intense laser radiation at VUV and soft X-ray wavelengths. In January 2005, it generated its first laser pulses with a 32 nm wavelength, the shortest wavelength ever achieved with a FEL, and then started up for users in August. It is available for research groups from all over the world for experiments in areas such as cluster physics, solid-state physics, plasma research and biology. Four experimental stations are currently available, at which different instruments can be operated alternately.
Since the official start-up in August, a total of 14 research teams from 10 countries have carried out experiments ranging from generating and measuring plasmas to the first investigations of experimental methods for studying complex biomolecules, which will later be used at the European X-ray FEL (XFEL). As expected, the laser pulses of the VUV-FEL are shorter than 50 fs. This allows researchers to trace various processes on extremely short time scales by taking time-resolved “snapshots” of the reaction process. Investigating such time-resolved processes with radiation of short wavelengths is one of the most important new applications of this kind of X-ray laser.
Before user experiments resume in May, the DESY team is carrying out machine studies to improve the stability of the facility, increase the energy of the laser pulses, and shorten the wavelength of the radiation to around 15 nm. At the same time, various studies are being done to prepare for the planned XFEL, which will be 3.4 km long and generate even shorter wavelengths, down to 0.085 nm, when it comes into operation in 2013. The VUV-FEL should produce its shortest wavelength of 6 nm in 2007, after an additional accelerator module is installed.
