The investigation of ultrafast dynamics, taking place on the few to sub-picosecond time scale, is today a very active research area pursued in a variety of scientific domains. With the recent advent of X-ray free-electron lasers (XFELs), providing very intense X-ray pulses of duration as short as a few femtoseconds, this research field has gained further momentum. As a consequence, the demand for access strongly exceeds the capacity of the very few XFEL facilities existing worldwide. This situation motivates the development of alternative sub-picosecond pulsed X-ray sources among which femtoslicing facilities at synchrotron radiation storage rings are standing out due to their tunability over an extended photon energy range and their high stability. Following the success of the femtoslicing installations at ALS, BESSY-II, SLS and UVSOR, SOLEIL decided to implement a femtoslicing facility. Several challenges were faced, including operation at the highest electron beam energy ever, and achievement of slice separation exclusively with the natural dispersion function of the storage ring. SOLEIL's setup also enables, for the first time, delivering sub-picosecond pulses simultaneously to several beamlines. This last feature enlarges the experimental capabilities of the facility, which covers the soft and hard X-ray photon energy range. In this paper, the commissioning of this original femtoslicing facility is reported. Furthermore, it is shown that the slicing-induced THz signal can be used to derive a quantitative estimate for the degree of energy exchange between the femtosecond infrared laser pulse and the circulating electron bunch.

The aim of the Femto-Slicing project at SOLEIL is to generate 100 - 200 fs FWHM short X-ray pulses on two beamlines, CRISTAL and TEMPO, for pump-probe experiments in the spectral range of hard and soft X-rays. We note that this capability could be extended in the future to two or three more beamlines. Femtosecond lasers are currently in operation on TEMPO and CRISTAL beamlines, for pump-probe experiments on the ps time scale, enabling time resolved photo-emission and photo-diffraction studies, respectively. The Femto-Slicing project is based on the fs laser of the CRISTAL beamline, which can be adjusted to deliver 3 to 5 mJ pulses of 30 fs duration at 2.5 to 1 kHz, respectively. This laser beam is separated in three branches: one delivering about 2 mJ to the modulator wiggler and the other ones delivering the remaining energy to the experiments on the TEMPO and CRISTAL beamlines. This layout will yield natural synchronisation between Infra-Red (IR) laser pump and X-ray probe pulses, only affected by jitter and drift associated with beam transport. In this paper, we present the progress in the implementation and commissioning of the laser beam transport system and its characterization.

The femtoslicing project at SOLEIL is currently under commissioning. It will enable to serve several beamlines with 100 fs FWHM long pulses of soft and hard X-rays with reasonable flux and with a 1 kHz repetition rate. It is based on the interaction of a femtosecond Ti:Sa laser with electrons circulating in the magnetic field of a modulator wiggler, that provides the electron beam energy modulation on the length scale of the laser pulse. The optimization of the interaction is performed using two dedicated diagnostics stations. The first one, operating in the Infra-Red (IR) is installed in the tunnel and allows the adjustment of the temporal, spectral and spatial overlap between the laser and the electron beam. The second one, located in the IR-THz AILES beamline, measures the intensity of the terahertz (THz) radiation emitted by the local dip structure produced in the core electron beam after interaction. This second setup provides refined optimization of the interaction. This paper describes the layout of these diagnostics and gives first results and characterization of the slicing experiment at SOLEIL.

The 2.75 GeV synchrotron light source SOLEIL delivers photons to 27 beamlines; 2 new ones are under construction together with the FEMTOSLICING project of which commissioning started in January 2014. Five filling patterns are available for the users in Top-up injection mode. The storage ring is running with an upgraded optics less sensitive to insertion device (ID) configurations and giving both better beam lifetime and injection efficiency. The beam position stability remains excellent with a focus on electron vertical beam-size stability for the new very long beamlines. A gating system during Top-up injection improves significantly the quality of the spectrum on an infrared beamline. Several heavy actions of maintenance and upgrades on crucial subsystem equipment are underway. Others accelerator projects are going on such as the design and construction of new IDs, new Multipole Injection Kicker, radiation damage studies as well as R&D on solid-state amplifiers.

The aim of the Femto-Slicing project at SOLEIL is to generate 100 fs X-rays pulses on two beamlines, CRISTAL and TEMPO, for pump-probe experiments in the hard and soft X-rays regions. Two fs lasers are currently in operation on TEMPO and CRISTAL for pump-probe experiments on the ps time scale enabling time resolved photoemission and photodiffraction studies. The Femto-Slicing project is based on the fs laser of the CRISTAL beamline, which can be adjusted to deliver 3 mJ pulses of 30 fs duration at 2.5 kHz. The laser beam will be separated in three branches: one delivering about 2 mJ to the modulator Wiggler and the other ones delivering the remaining energy to the TEMPO and CRISTAL experiments. This layout will yield natural synchronization between IR laser pump and X-ray probe pulses, only affected by jitter associated with beam transport. In this paper, we present the current status of the Femto-Slicing project at SOLEIL, with particular emphasis on the expected performance, and the design and construction of the laser beam transport and the diagnostics implementation.

An electron bunch slicing setup is presently under construction on the SOLEIL storage ring for delivering 100 fs (rms) long photon pulses to two undulator-based beamlines providing soft (TEMPO) and hard X-rays (CRISTAL). Thanks to the non-zero dispersion function present in all straight sections of the storage ring, the sliced bunches can be easily separated from the core bunches. The modulator is a wiggler composed of 20 periods of 164.4 mm. It produces a magnetic field of 1.8 T at a minimum gap of 14.5 mm. To modulate the kinetic energy of the electrons in the wiggler, a Ti:Sa laser will be used, which produces 50 fs pulses at 800 nm with a repetition rate of 2.5 kHz. The laser beam is splitted into two branches in order to provide 2 mJ to the modulator and 0.5 mJ as pump pulse for the CRISTAL and TEMPO end stations. Focusing optics and beam path, from the laser hutch to the inside of the storage ring tunnel are presently under finalization. In this paper, we will report on the specificities of the SOLEIL setup, the status of its installation and the expected performances.