1. 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

2. 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 nm
Fermi
4-100 nm
SwissFEL nm
SACLA nm
EuPRAXIA
SPARC_LAB
3 -5 nm
Why not 2 nm?
Wavelength (nm)
Energy (eV)

3. 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

4. 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)

5. 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

6. 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 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

7. 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

8. 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)

9. 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

10. 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)

11. 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

12. 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€

13. 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 …

14. 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 ???
???