FEL2013 - List of Authors (Saldin, E.)

Paper	Title	Page
WEPSO20	Wake Monochromator in Asymmetric and Symmetric Bragg and Laue Geometry for Self-seeding the European X-ray FEL	538
	G. Geloni, V. Kocharyan, E. Saldin, S. Serkez, M. Tolkiehn DESY, Hamburg, Germany
	We discuss the use of self-seeding schemes with wake monochromators to produce TW power, fully coherent pulses for applications at the dedicated bio-imaging bealine at the European X-ray FEL, a concept for an upgrade of the facility beyond the baseline previously proposed by the authors. We exploit the asymmetric and symmetric Bragg and Laue reflections (σ polarization) in diamond crystal. Optimization of the bio-imaging beamline is performed with extensive start-to-end simulations, which also take into account effects such as the spatio-temporal coupling caused by the wake monochromator. The spatial shift is maximal in the range for small Bragg angles. A geometry with Bragg angles close to pi/2 would be a more advantageous option from this viewpoint, albeit with decrease of the spectral tunability. We show that it will be possible to cover the photon energy range from 3 keV to 13 keV by using four different planes of the same crystal with one rotational degree of freedom.

WEPSO34	Proposal for a Scheme to Generate a 10 tw Power Level, Femtosecond X-ray Pulses for Bio-imaging of Single Protein Molecules at the European XFEL	574
	V. Kocharyan, G. Geloni, E. Saldin, S. Serkez, I. Zagorodnov DESY, Hamburg, Germany O. Yefanov CFEL, Hamburg, Germany
	Crucial parameters for bio-imaging experiments are photon energy range, peak power and pulse duration. For a fixed resolution, the largest diffraction signals are achieved at the longest wavelength supporting that resolution. In order to perform these experiments at the European XFEL, we propose to use a novel configuration combining self-seeding and undulator tapering techniques with the emittance-spoiler method. Experiments at the LCLS confirmed the feasibility of these three techniques. Their combination allows obtaining a dramatic increase the XFEL output peak power and a shortening of the photon pulse duration to levels sufficient for performing bio-imaging of single protein molecules at the optimal photon-energy range between 3 keV and 5 keV. We show here that it is possible to achieve up to a 100-fold increase in peak-power of the X-ray pulses at the European XFEL: the X-ray beam would be delivered in 10 fs-long pulses with 50 mJ energy each at a photon energy around 4 keV. We confirm by simulations that one can achieve diffraction before destruction with a resolution of 0.25 nm resolution.

WEPSO57	Optimization of a Dedicated Bio-imaging Beamline at the European X-ray Fel	632
	E. Saldin, G. Geloni, V. Kocharyan, S. Serkez DESY, Hamburg, Germany
	We recently proposed a basic concept for design and layout of a dedicated undulator source for bio-imaging experiments at the European XFEL. Here we present an optimization of that concept. The core of the scheme is composed by soft and hard X-ray self-seeding setups. Using an improved design for both monochromators it is possible to increase the design electron energy up to 17.5 GeV in photon energy range between 2 keV and 13 keV, which is the most preferable for life science experiments. Operating at such high electron energy one increases the X-ray output peak power. Moreover, 17.5 GeV is the preferred operation energy for SASE1 and SASE2 users. This choice will reduce the interference with other undulator lines. We include a study of the performance of the self-seeding scheme accounting for spatiotemporal coupling caused by the use of a single crystal monochromator. This distortion can be easily suppressed by the right choice of diamond crystal planes. The proposed undulator source yields about the same performance as in the case for a X-ray seed pulse with no coupling. Simulations show that the FEL power reaches 2 TW in the 3 keV - 5 keV photon energy range.

WEPSO63	Extension of SASE Bandwidth up to 2 % as a Way to Increase Number of Indexed Images for Protein Structure Determination by Femtosecond X-Ray Nanocrystallography at the European XFEL	661
	S. Serkez, V. Kocharyan, E. Saldin, I. Zagorodnov DESY, Hamburg, Germany G. Geloni XFEL. EU, Hamburg, Germany O. Yefanov CFEL, Hamburg, Germany
	Experiments at the LCLS confirmed the feasibility of femtosecond nanocrystallography for protein structure determination at near-atomic resolution. These experiments rely on X-ray SASE pulses with a few microradians angular spread, and about 0.2 % bandwidth. By indexing individual patterns and then summing all counts in all partial reflections for each index it is possible to extract the square modulus of the structure factor. The number of indexed images and the SASE bandwidth are linked, as an increasing number of Bragg spots per individual image requires an increasing spectral bandwidth. This calls for a few percent SASE bandwidth. Based on start-to-end simulations of the European XFEL baseline, we demonstrate that it is possible to achieve up to a 10-fold increase of the electron energy chirp by strongly compressing a 0.25 nC electron bunch. This allows for data collection with a 2 % SASE bandwidth, a few mJ radiation pulse energy and a few fs-pulse duration, which would increase the efficiency of protein determination at the European XFEL. We prove this concept with simulations of photosystem-I nanocrystals, with a size of about 300 nm.

WEPSO64	Grating Monochromator for Soft X-ray Self-seeding the European XFEL	667
	S. Serkez, G. Geloni, V. Kocharyan, E. Saldin DESY, Hamburg, Germany
	Self-seeding implementation in the soft X-ray wavelength range involves gratings as dispersive elements. We study a very compact self-seeding scheme with a grating monochromator originally designed at SLAC, which can be straightforwardly installed in the SASE3 undulator beamline at the European XFEL. The design is based on a toroidal VLS grating at a fixed incidence angle, and without entrance slit. It covers the spectral range from 300 eV to 1000 eV. The performance was evaluated using wave optics method vs ray tracing methods. Wave optics analysis takes into account the actual beam wavefront of the radiation from the FEL source, third order aberrations, and errors from optical elements. We show that, without exit slit, the self-seeding scheme gives the same resolving power (about 7000) as with an exit slit. Wave optics is also naturally applicable to calculations of the scheme efficiency, which include the monochromator transmittance and the effect of the mismatching between seed beam and electron beam. Simulations show that the FEL power reaches 1 TW, with a spectral density about two orders of magnitude higher than that for the SASE pulse at saturation.

Paper

Title

Page

Wake Monochromator in Asymmetric and Symmetric Bragg and Laue Geometry for Self-seeding the European X-ray FEL

538

G. Geloni, V. Kocharyan, E. Saldin, S. Serkez, M. Tolkiehn
DESY, Hamburg, Germany

We discuss the use of self-seeding schemes with wake monochromators to produce TW power, fully coherent pulses for applications at the dedicated bio-imaging bealine at the European X-ray FEL, a concept for an upgrade of the facility beyond the baseline previously proposed by the authors. We exploit the asymmetric and symmetric Bragg and Laue reflections (σ polarization) in diamond crystal. Optimization of the bio-imaging beamline is performed with extensive start-to-end simulations, which also take into account effects such as the spatio-temporal coupling caused by the wake monochromator. The spatial shift is maximal in the range for small Bragg angles. A geometry with Bragg angles close to pi/2 would be a more advantageous option from this viewpoint, albeit with decrease of the spectral tunability. We show that it will be possible to cover the photon energy range from 3 keV to 13 keV by using four different planes of the same crystal with one rotational degree of freedom.

WEPSO34

Proposal for a Scheme to Generate a 10 tw Power Level, Femtosecond X-ray Pulses for Bio-imaging of Single Protein Molecules at the European XFEL

574

V. Kocharyan, G. Geloni, E. Saldin, S. Serkez, I. Zagorodnov
DESY, Hamburg, Germany
O. Yefanov
CFEL, Hamburg, Germany

Crucial parameters for bio-imaging experiments are photon energy range, peak power and pulse duration. For a fixed resolution, the largest diffraction signals are achieved at the longest wavelength supporting that resolution. In order to perform these experiments at the European XFEL, we propose to use a novel configuration combining self-seeding and undulator tapering techniques with the emittance-spoiler method. Experiments at the LCLS confirmed the feasibility of these three techniques. Their combination allows obtaining a dramatic increase the XFEL output peak power and a shortening of the photon pulse duration to levels sufficient for performing bio-imaging of single protein molecules at the optimal photon-energy range between 3 keV and 5 keV. We show here that it is possible to achieve up to a 100-fold increase in peak-power of the X-ray pulses at the European XFEL: the X-ray beam would be delivered in 10 fs-long pulses with 50 mJ energy each at a photon energy around 4 keV. We confirm by simulations that one can achieve diffraction before destruction with a resolution of 0.25 nm resolution.

WEPSO57

Optimization of a Dedicated Bio-imaging Beamline at the European X-ray Fel

632

E. Saldin, G. Geloni, V. Kocharyan, S. Serkez
DESY, Hamburg, Germany

We recently proposed a basic concept for design and layout of a dedicated undulator source for bio-imaging experiments at the European XFEL. Here we present an optimization of that concept. The core of the scheme is composed by soft and hard X-ray self-seeding setups. Using an improved design for both monochromators it is possible to increase the design electron energy up to 17.5 GeV in photon energy range between 2 keV and 13 keV, which is the most preferable for life science experiments. Operating at such high electron energy one increases the X-ray output peak power. Moreover, 17.5 GeV is the preferred operation energy for SASE1 and SASE2 users. This choice will reduce the interference with other undulator lines. We include a study of the performance of the self-seeding scheme accounting for spatiotemporal coupling caused by the use of a single crystal monochromator. This distortion can be easily suppressed by the right choice of diamond crystal planes. The proposed undulator source yields about the same performance as in the case for a X-ray seed pulse with no coupling. Simulations show that the FEL power reaches 2 TW in the 3 keV - 5 keV photon energy range.

WEPSO63

Extension of SASE Bandwidth up to 2 % as a Way to Increase Number of Indexed Images for Protein Structure Determination by Femtosecond X-Ray Nanocrystallography at the European XFEL

661

S. Serkez, V. Kocharyan, E. Saldin, I. Zagorodnov
DESY, Hamburg, Germany
G. Geloni
XFEL. EU, Hamburg, Germany
O. Yefanov
CFEL, Hamburg, Germany

Experiments at the LCLS confirmed the feasibility of femtosecond nanocrystallography for protein structure determination at near-atomic resolution. These experiments rely on X-ray SASE pulses with a few microradians angular spread, and about 0.2 % bandwidth. By indexing individual patterns and then summing all counts in all partial reflections for each index it is possible to extract the square modulus of the structure factor. The number of indexed images and the SASE bandwidth are linked, as an increasing number of Bragg spots per individual image requires an increasing spectral bandwidth. This calls for a few percent SASE bandwidth. Based on start-to-end simulations of the European XFEL baseline, we demonstrate that it is possible to achieve up to a 10-fold increase of the electron energy chirp by strongly compressing a 0.25 nC electron bunch. This allows for data collection with a 2 % SASE bandwidth, a few mJ radiation pulse energy and a few fs-pulse duration, which would increase the efficiency of protein determination at the European XFEL. We prove this concept with simulations of photosystem-I nanocrystals, with a size of about 300 nm.

WEPSO64

Grating Monochromator for Soft X-ray Self-seeding the European XFEL

667

S. Serkez, G. Geloni, V. Kocharyan, E. Saldin
DESY, Hamburg, Germany

Self-seeding implementation in the soft X-ray wavelength range involves gratings as dispersive elements. We study a very compact self-seeding scheme with a grating monochromator originally designed at SLAC, which can be straightforwardly installed in the SASE3 undulator beamline at the European XFEL. The design is based on a toroidal VLS grating at a fixed incidence angle, and without entrance slit. It covers the spectral range from 300 eV to 1000 eV. The performance was evaluated using wave optics method vs ray tracing methods. Wave optics analysis takes into account the actual beam wavefront of the radiation from the FEL source, third order aberrations, and errors from optical elements. We show that, without exit slit, the self-seeding scheme gives the same resolving power (about 7000) as with an exit slit. Wave optics is also naturally applicable to calculations of the scheme efficiency, which include the monochromator transmittance and the effect of the mismatching between seed beam and electron beam. Simulations show that the FEL power reaches 1 TW, with a spectral density about two orders of magnitude higher than that for the SASE pulse at saturation.