The Free Electron Laser EuPRAXIA@SPARC_LAB Ideas & Requirements for a EUV/soft x-rays beamline WG 4.3 – FEL pilot applications Marcello Coreno1, Stefano Lupi2, Augusto Marcelli3, Alessandro Ricci4, Francesco Stellato3, Fabio Villa3 1 CNR - ISM 2 Università di Roma «La Sapienza» 3 INFN 4 DESY Hamburg

Coherent EUV-soft x-ray FELs Facts Different machines, different working schemes (SASE, SEEDED) BUT Strong interest in being SOFT Non-linear processes not accessible for 3°rd generation sources FLASH 4.2–50 nm LCLS 0.1-2.8 nm Fermi 4-100 nm SwissFEL 0.1- 7 nm SACLA 0.1-0.8 nm EuPRAXIA SPARC_LAB 3 -5 nm Why not 2 nm? 0.1 1 10 Wavelength (nm) 12.000 1.200 120 Energy (eV)

FELs Vs Synchrotrons FELs have higher peak brilliance than synchrotrons  Diffract-and-destroy FELs emit femtosecond pulses, synchrotrons picosecond ones  Ultrafast time-resolution FELs have higher coherence than synchrotrons Coherent imaging experiments FELs & synchrotrons are both tunable in wavelength and polarization FELs have (few) serial users synchrotrons have (many) parallel users

Coherent EUV-soft x-ray FELs Science Overview Why FELs (and not synchrotrons) ? Ultra-high brilliance, coherence, short pulse length Diffract-and-destroy regime Non-linear processes Pump-probe schemes with ultrafast resolution Which experiments? Biological & non-biological coherent imaging (pump-probe, time-resolved experiments) 0 fs 2 fs 5 fs 10 fs 20 fs 50 fs Sample FEL Pattern FT-1 Reconstruction Neutze et al. Nature (2000) Chapman et al. Nature Physics (2006) Key number: peak brilliance, i.e. # photons/pulse (with fs pulses) Van der Shoot et al. Nature Comm (2015) Pfau et al. Nature Comm (2012)

The coherent EUV-soft x-ray FEL @ LNF Scientific goals The EUV-soft x-ray FEL in Frascati One experimental endstation  One (wide) class of experiments Time-resolved Coherent Imaging of complex systems Biological systems Cells, organelles, viruses Samples with 500 nm-10 µm size Inorganic systems Mesoscopic Systems High-temperature superconductors Plasma and Nanoparticles

The coherent EUV-soft x-ray FEL @ LNF Scientific goals Water Window Coherent Imaging of biological systems Energy region between Oxygen and Carbon K-edge 2.34 nm – 4.4 nm (530 eV -280 eV). Water is almost transparent to radiation in this range while nitrogen and carbon are absorbing (and scattering) 3 nm 2 nm Coherent Imaging of biological samples in their native state Possibility to study dynamics A carboxisome diffraction pattern and its reconstruction From LCLS data Hantke et al. Nature Photonics (2014) Resolution is wavelength limited & depends on photon flux

The coherent EUV-soft x-ray FEL @ LNF Scientific goals Time-resolved Resonant (Magnetic) Scattering & Diffraction Wavelength: 4 nm – 0.8 nm ( 300 eV - 1500 eV) Higher Harmonics have to be used High temperature superconductors Metal-insulating transition Colossal magnetoresistance Ferroelectrics & multiferroics Skyrmions, spintronics Nanoparticles and plasma Setting the FEL energy at the L3-edge and probing the dipole transition from 2p core levels to 3d states A strong resonant enhancement of the magnetic reflections can be observed n SAXS or WAXS Resonant X-ray Scattering (RXS) Combining RXS with IR-pump FEL-probe technique magnetic domains fluctuations on a tens of femtoseconds scale Fundamental physics, but wide application in technology and industry

Source Parameters The proposed class of experiments will be possible provided that: 1Going down to 2 nm (600 eV) would highly improve the scientific interest 2Higher harmonics are of interest, provided that they carry enough photons Parameter Required Value Wavelength1,2 3 nm (400 eV) [2 nm (600 eV)] Flux (photons/pulse) >1013 ΔE/E (FWHM) 10-3 Photon beam size (FWHM) <3-5 µm  1 µm Position Stability (shot to shot) < 1 µm Polarization Linear and circular Harmonics Even (and odd, if possible) Coherence Maximal (and measurable)

The Experimental Endstation A FEL experimental endstation must have Ultra-high vacuum experimental chamber Beam diagnostics: photon-in and photon out spectrometers, I0 monitor and attenuator, filters , ... Sample diagnostics: time-of-flight spectrometer Synchronized external lasers (tunable, high power – multiTW, PW?; optical, IR, THz) Split-and-delay element - Sample delivery systems Liquid jets Aerosol Fixed targets 2D detector Sample FEL beam 10 μm

Detectors Large area two dimensional detectors Low-noise: to cope with weak signals High dynamic-range: to cope with higlhy and weakly scattering samples Small-pixel (< 100x100 µm2) to get higher spacial resolution Fast-readout to match that of the FEL source Market-available solutions: pnCCDs , Princeton Instruments, Dectris (Pilatus, Eiger)  €€€ It is possible to design and build a detector within the community (CSN5) R&D in collaboration with other institutes, e.g. IHEP (China)

The Experimental Endstation Pros: Space for optics & diagnostics Distance between undulator and mirrors Cons: beam stability beam diagnostics far from the experiment 15 m 2.0 m ? Sample injection TOF Optics & Diagnostics 2.0 m Chamber XUV S&D BD KB mirrors 2.0 m P P 2.0 m 2.5 m P S&D: Split&Delay line KB: Kirkpatrick-Baez mirrors BD: (Photon in) beam diagnostics TOF: Time-of-flight spectrometer XUV: (Photon out) spectrometer and diagnostics P: pumps Laser Table 20 m 5.0 m

The Experimental Endstation Space and €€€ Requirements Minimal requirements for beamline and optics - 15x20 m2 (at least) for the experimental hall (not including optics & beam diagnostics) - Experimental chamber(s) - Sample delivery station - Vacuum components (pumps) - Gases (He, N2, Ar) and gas lines - Optical pump laser Others Space for control devices Space for computers Space for users (including data evaluation) Sample preparation laboratory Fridge, centrifuges, microscopes Does not seem to be too much stuff, but this is how it actually looks like! Picture taken at FLASH beamline 2 during water window measurements Budget requirements  2 M€

Thank you for the attention! Conclusions Under the following conditions: Space requirements Source parameters: wavelength, photon flux, coherence, pulse length, … Money & people Eusparc will be able to have One experimental endstation to perform exciting FEL science Thank you for the attention! Questions ??? ??? Discussion …

Thank you for the attention! Conclusions One experimental endstation to perform exciting FEL science @ LNF is possible, provided that: - Space requirements - Source parameters: wavelength, photon flux, coherence, pulse length, … - Money & people Thank you for the attention! Questions ??? ???