a source for coherent radiation production in the soft X-ray

energy range

The SPARX FEL ProjectThe SPARX FEL Project

Main components of a Free Electron Laser • an accelerator providing a bunched relativistic electron beam• an undulator magnetElectrons are not bound in atomic, molecular or solid-state levels but are moving freely in vacuum

For visible or infrared light an optical resonator can be usedAt below 100 nm the reflectivity of metals and other mirror coatings drops quickly to zero at normal incidence.

The principle of Self-Amplifified Spontaneous Emission (SASE) allows the realization of high-gain FELs at these short ‘s

The Principle of Self-Amplified Spontaneous Emission (SASE) X-FELs

Sparx

X-FEL ~ 0.1 nm 2013

Fermi1 100 40 nm 2010

Fermi2 40 10 nm 2011

SPARX 13 1 nm 2013

SPARC 500 100 nmcommissioning

FLASH 13 6.5 nm in operation

100 nm ≈ 12 eVh=6.6x10-34 J.s = 4.1 x 10 -15 eV.sh = 12 eV= 12 eV/h ≈ 3 x 10 15 s-1

= c/= 3 x 10 8ms-1/ 3 x 10 15 s-1= 10 -7 m = 100 nm= [h(eV.s).c]/E(eV)=(12.4 x 10 -7eV.m)/E(eV)

Peak brightness (brilliance) versus pulse duration of various types of radiation

sources

UK

GE

IT

GE

ITCH

CH

Free-electron laser used in

human brain/eye surgery

Use of the FEL to help remove a tumor from the brain of a patient. Unlike conventional lasers that produce light at given wavelengths, the FEL beam can be tuned through a wide spectrum of colors. That has allowed researchers to find the optimal wavelength (6.45µm) for cutting cleanly through living tissue.

Neutze et al. Nature (2000) 406:752

X-ray intensity, I(t) = 3 x 1012 (12 keV~1Å) photons per 100-nm diameter spot (3.8 x 106 photons per Å2)

Explosion of T4 Lysozyme

= [h(eV.s).c]/E(eV)=(12.4 x 10 -7eV.m)/E(eV)

Reconstructed image

No sign of radiation damage

Diffraction pattern from the

subsequent pulse

The first pulse destroyed the object after recording the

image

CCD detector recording a continuous

diffraction pattern

A coherent diffraction pattern of

the object

recorded from a single

25-femtosecond FEL pulse

K.J. Gaffney, H.N. Chapman Science 316, 1444 (2007)

Schematic depiction of single-particle coherent diffractive imaging with an XFEL pulse

plasma formation

Coulomb explosion

3D diffraction data set is assembled from noisy diffraction patterns of identical particles in random and unknown

orientations.

The image is then obtained by phase

retrieval

Fourier amplitude of (a) + Fourier phases of (b)

Fourier amplitude of (b) + Fourier phases of (a)

The Importance of the Phase Information

(a) (b)

A Scanning ElectronMicroscopy image

An oversampled diffraction pattern

Image reconstructed from (b)

Miao, Charalambous, Kirz & Sayre, Nature 400, 342 (1999).

The First Experimental Demonstration

(c)

(a) (b)

Henry Chapman: Flash Diffraction Imaging of Biological Samples

FLASH: 45 proposals 32 approved

Tor Vergata FEL colloquiaMarch, 19, 2008 – Prof. Giorgio Margaritondo

Ecole Polytechnique Fédérale de Lausanne, Switzerland  "Coherent Radiology - from Synchrotrons to Free Electron Lasers"

Aprile, 2, 2008 – Prof. Jianwei (John) MiaoDepartment of Physics and Astronomy, Univ. of California,

USA  "Coherent Scattering, Oversampling and Applications of X-ray Free

Electron Lasers" April, 23, 2008 – Prof. Janos Hajdu

Structural Biology Labs Biomedical Centre, Uppsala, Sweden“TBA”

June, 18, 2008 – Prof. Massimo Altarelli European X-ray Free-Electron Laser Project Team,

DESY,Germany“The European X-ray Free-Electron Laser Project in

Hamburg”