A milestone reached in the femto-slicing project

Finally approved late 2011 and launched in 2012, this project aims at generating X-ray pulses on a scale of a few dozens of femtoseconds (10^-15 seconds) by interaction between a femtosecond laser and the synchrotron radiation.

These ultra-short pulses will allow probing ultra-fast dynamic structures (eg chemical reactions, phase transitions, rapid structural changes in crystals, magnetization reversals) via time-resolved experiments carried out on CRISTAL and TEMPO beamlines.

**Photo on left :** Philippe Hollander, laser engineer, and Pascale Prigent, femto-slicing assistant project manager (for the beamlines), in the laser system hutch. **Photo on right :** From left to right: in the synchrotron control room, Amor Nadji, Director of the Accelerators and Sources Division & femto-slicing project manager (for the Sources&Accelerators); Marie-Agnès Tordeux, co-head of the project commissionning (for the Sources&Accelerators); Lodovico Cassinari, in charge of the Diagnostics Group; Paul Morin, Director of the Scientific Division; Jean Daillant, SOLEIL CEO, and Marie Labat co-head of the project commissionning (for the beamlines).

On 29 September, for the first time, the signal showing that the interaction between the laser and the synchrotron radiation happens in the storage ring was detected.
(see photo 3: on the screen you can see the signal due to the coherent synchrotron radiation (SR) in the field of THz generated by the laser/SR interaction).

**Photo :** Marie-Agnès Tordeux and Marie Labat, close to the display screen of the bolometer, which indicates the presence of the laser/synchrotron beam interaction.

The next steps forward will consist in optimizing the THz signal, making sure that the SR/laser interaction is reproducible, and defining a users’ operation mode, that will be integrated in the beam schedule.