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B. Badelek,
C. Blochinger,
J.Blumlein,
E. Boos,
R. Brinkmann,
H. Burkhardt,
P. Bussey,
C. Carimalo,
J. Chyla,
A. K. Ciftci, [......],
I. Watanabe,
T. Wengler,
I. Will,
S. Wipf,
O. Yavas,
K. Yokoya,
M. Yurkov,
A. F. Zarnecki,
P. Zerwas,
F. Zomer
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T Kamps,
W Anders,
A Frahm,
J Knobloch,
O Kugeler,
J Rudolph,
A Matveenko,
A Neumann, T Quast,
M Schenk,
M Schuster,
P Kneisel,
J Sekutowicz,
R Nietubyc,
I Will
[show abstract]
[hide abstract]
ABSTRACT: As part of the BERLinPro study, HZB is developing an SRF photoelectron injector. The R&D will be carried out in three stages, the first of which is currently being installed at HZB's HoBiCaT facility. It consists of an SRF cavity with SC solenoid, electron beam diagnosics and drivelaser systems.
Journal of Physics Conference Series 06/2011; 298(1):012009.
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[show abstract]
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ABSTRACT: We present femtosecond x-ray absorption experiments investigating the electron and spin dynamics in a thin nickel film after
excitation by an optical fs laser pulse. By changing between linearly and circularly polarized x-rays, the electron and spin
dynamics can be investigated individually. A temporal response as fast as 120 fs is found.
12/2008: pages 194-196;
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ABSTRACT: The new femtosecond-slicing source generates energy-tuneable femtosecond x-ray pulses which are used for time-resolved soft
x-ray spectroscopy. We report on the experimental setup and show first results using the laser pump and x-ray probe technique.
12/2008: pages 119-121;
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H.A. Durr,
C. Stamm,
T. Kachel,
N. Pontius,
R. Mitzner, T. Quast,
K. Holldack,
S. Khan,
C. Lupulescu,
E.F. Aziz,
M. Wietstruk,
W. Eberhardt
[show abstract]
[hide abstract]
ABSTRACT: We present the first X-ray absorption spectrum over an entire absorption edge using femtosecond pulses from a synchrotron-based slicing source. An ultrafast laser pulse excited a nickel film, and a succeeding X-ray pulse from the BESSY femtoslicing facility probed the Ni L<sub>3</sub>-edge. By choosing either linear or circular X-ray polarization, the spectra represent snapshots of the electronic or the magnetic state, respectively, with an exposure time of about 100 fs. We find an almost instantaneous response of the electronic system to the laser pulse, and provide a first direct measurement of the quenching of magnetic moments within 120 fs.
IEEE Transactions on Magnetics 08/2008; · 1.36 Impact Factor
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C Stamm,
T Kachel,
N Pontius,
R Mitzner, T Quast,
K Holldack,
S Khan,
C Lupulescu,
E F Aziz,
M Wietstruk,
H A Dürr,
W Eberhardt
[show abstract]
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ABSTRACT: The rapidly increasing information density required of modern magnetic data storage devices raises the question of the fundamental limits in bit size and writing speed. At present, the magnetization reversal of a bit can occur as quickly as 200 ps (ref. 1). A fundamental limit has been explored by using intense magnetic-field pulses of 2 ps duration leading to a non-deterministic magnetization reversal. For this process, dissipation of spin angular momentum to other degrees of freedom on an ultrafast timescale is crucial. An even faster regime down to 100 fs or below might be reached by non-thermal control of magnetization with femtosecond laser radiation. Here, we show that an efficient novel channel for angular momentum dissipation to the lattice can be opened by femtosecond laser excitation of a ferromagnet. For the first time, the quenching of spin angular momentum and its transfer to the lattice with a time constant of 120+/-70 fs is determined unambiguously with X-ray magnetic circular dichroism. We report the first femtosecond time-resolved X-ray absorption spectroscopy data over an entire absorption edge, which are consistent with an unexpected increase in valence-electron localization during the first 120+/-50 fs, possibly providing the driving force behind femtosecond spin-lattice relaxation.
Nature Material 11/2007; 6(10):740-3. · 32.84 Impact Factor
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C. Stamm,
T. Kachel,
N. Pontius,
R. Mitzner, T. Quast,
K. Holldack,
S. Khan,
C. Lupulescu,
E. F. Aziz,
M. Wietstruk,
H. A. D|[uuml]|rr,
W. Eberhardt
[show abstract]
[hide abstract]
ABSTRACT: The rapidly increasing information density required of modern magnetic data storage devices raises the question of the fundamental limits in bit size and writing speed. At present, the magnetization reversal of a bit can occur as quickly as 200 ps (ref.
Nature Material 08/2007; 6(10):740-743. · 32.84 Impact Factor
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[show abstract]
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ABSTRACT: As the first undulator-based source, the BESSY femtoslicing source has succesfully demonstrated its capabilities of providing 100 fs x-ray pulses in an energy range from 400 to 1400 eV with linear and circular polarisation. Even with a better signal-to-noise ration compared to the slicing sources utilizing radiation from a bending magnet the number of detected photons at the user frontend is still limited to ap 10<sup>3</sup>/s. To increase the photon flux the laser system was upgraded to a higher repetition rate. A new beamline utilizing a reflective zone-plate was installed. Finally a new vacuum guided laser beam path will be implemented for better stability.
Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007
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M. Abo-Bakr,
W. Anders,
J. Bahrdt,
K. Burkmann,
P. Budz,
O. Dressier,
H. Durr,
V. Durr,
W. Eberhardt,
S. Eisebitt, [......],
A. Neumann,
M. Neeb,
K. Ott,
D. Pfluckhahn, T. Quast,
M. Scheer,
T. Schroeter,
M. Schuster,
F. Senf,
G. Wiistefeld
[show abstract]
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ABSTRACT: BESSY is proposing a demonstration facility, called STARS, for a two-stage high-gain harmonic generation free electron laser (HGHG FEL). STARS is planned for lasing in the wavelength range 40 to 70 nm, requiring a beam energy of 325 MeV and peak current of 500 A. The facility consists of a normal conducting gun, three superconducting TESLA-type acceleration modules modified for CW operation, a single stage bunch compressor and finally a two-stage HGHG cascaded FEL. This paper describes the faciliy layout and the rationale behind the operation parameters.
Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007
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[show abstract]
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ABSTRACT: At BESSY II an undulator‐based femtoslicing source is in operation. It provides soft X‐ray radiation of tunable photon energy and polarization with a pulse length of less than 150 ± 50 fs. In this paper we discuss the beamline layout and our schemes of soft X‐ray photon detection with emphasis on special requirements for laser pump — X‐ray probe experiments with a time resolution of 150 fs. With our setup we have determined the characteristics of the fs soft X‐rays, i.e. their flux, temporal evolution, angular distribution, signal‐to‐background ratio, and polarization state. Pilot experiments, using fs soft X‐rays for absorption spectroscopy are presented. © 2007 American Institute of Physics
AIP Conference Proceedings. 01/2007; 879(1):1250-1253.
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[show abstract]
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ABSTRACT: A source of 100 fs x-ray pulses with tunable polarization and excellent
signal-to-background ratio has been constructed in 2004 at BESSY, based
on laser-induced energy modulation (``femtoslicing'') and subsequent
angular separation of the short-pulse x-rays from an elliptical
undulator. After commissioning at the BESSY II storage ring and
characterizing the source, short-pulse radiation is now routinely
delivered for pump-probe applications. The paper summarizes the results
from commissioning and operational experience as well as possible
upgrade options.
12/2006; 879:22-25.
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ABSTRACT: At the 1.7-GeV electron storage ring BESSY II, a first source of synchrotron radiation with 100 fs pulse duration, variable (linear and circular) polarization, tunable photon energy (300 to 1400 eV), and excellent signal-to-background ratio was constructed and is now in routine operation.
Physical Review Letters 09/2006; 97(7):074801. · 7.37 Impact Factor
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ABSTRACT: Femtosecond far-infrared radiation pulses in the THz spectral range were observed as a consequence of the energy modulation of 1.7 GeV electrons by femtosecond laser pulses in the BESSY storage ring in order to generate femtosecond x-ray pulses ("femtoslicing"). In addition to being crucial for diagnostics of the laser-electron interaction, the THz radiation itself is useful for experiments where intense ultrashort THz pulses of well-defined temporal and spectral characteristics are required.
Physical Review Letters 03/2006; 96(5):054801. · 7.37 Impact Factor
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[show abstract]
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ABSTRACT: The laser-induced energy modulation of relativistic electrons in the BESSY II storage ring was studied by temporal and spectral characterization of femtosecond far-infrared (THz) pulses being emitted after the electons have passed dispersive elements. The length of the femtosecond density modulation and its temporal decay have been measured as well as bunch shapes down to a length of 3 ps (rms). The THz diagnostics is crucial for the operation of the recently commissioned” femtoslicing” source at BESSY.
Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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[show abstract]
[hide abstract]
ABSTRACT: At the BESSY II storage ring, a femtosecond x-ray source with tunable polarization and excellent signal-to-background ratio has been constructed and commissioned in 2004. This source is based on laser-induced energy modulation (” femtoslicing”) and subsequent angular separation of the short-pulse x-rays emitted by an elliptical undulator.
Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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B. Badelek,
C. Blochinger,
J.Blumlein,
E. Boos,
R. Brinkmann,
H. Burkhardt,
P. Bussey,
C. Carimalo,
J. Chyla,
A. K. Ciftci, [......],
I. Watanabe,
T. Wengler,
I. Will,
S. Wipf,
O. Yavas,
K. Yokoya,
M. Yurkov,
A. F. Zarnecki,
P. Zerwas,
F. Zomer
[show abstract]
[hide abstract]
ABSTRACT: High energy photon colliders (γγ, γe) are based on e^-e^- linear colliders where high energy photons are produced using Compton scattering of laser light on high energy electrons just before the interaction point. This paper is a part of the Technical Design Report of the linear collider TESLA. Physics program, possible parameters and some technical aspects of the photon collider at TESLA are discussed.
Published in Int.J.Mod.Phys. A19, Issue 30 (2004) 5097-5186;
Comments: 102 pages, 41 figures, editor: V. Telnov
Journal reference: Int.J.Mod.Phys.A19:5097-5186,2004
DOI: 10.1142/S0217751X04020737
Report number: DESY 2001-011, ECFA 2001-209
Cite as: arXiv:hep-ex/0108012 or http://arxiv.org/abs/hep-ex/0108012
International Journal of Modern Physics A 12/2004; 19(30):5097-5186. · 1.05 Impact Factor
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[show abstract]
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ABSTRACT: Short electron bunches in storage rings emit strong THz and sub-THz radiation if the length of the bunches is lower than the wavelength of the radiation. Two strong broad band THz sources have been established at the BESSY storage ring: 1. Coherent THz generation by compressed bunches at 500 MHz repetition rate gained by up to 10<sup>7</sup> in average power compared to incoherent sources. 2. Recently, ultrashort THz radiation emitted by the interaction of a femtosecond laser at a repetition rate of 1 kHz and the electron bunch in an undulator was detected. Experimental results on bunch length measurement using THz radiation are presented.
Infrared and Millimeter Waves, 2004 and 12th International Conference on Terahertz Electronics, 2004. Conference Digest of the 2004 Joint 29th International Conference on; 11/2004
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H.-J. Backer,
J. Bahrdt,
H.A. Durr,
V. Durr,
W. Eberhardt,
A. Gaupp,
E. Jaeschke,
K. Holldack,
S. Khan,
D. Kramer, [......],
G. Reichardt, T. Quast,
M. Scheer,
F. Senf,
G. Wustefeld,
I. Hertel,
F. Noack,
W. Sandner,
I. Will,
N. Zhavoronkov
[show abstract]
[hide abstract]
ABSTRACT: The generation of femtosecond X-ray pulses with circular polarization is planned at BESSY II. The paper describes the underlying principle ("femtoslicing"), its technical implementation, and the expected output, based on simulations and measurements.
Particle Accelerator Conference, 2003. PAC 2003. Proceedings of the; 06/2003
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B Badelek,
C Blochinger,
J. Blumlein,
E. Boos,
R Brinkmann,
H Burkhardt,
P Bussey,
C. Carimalo,
J Chyla,
A. K. Ciftci, [......],
I Watanabe,
T Wengler,
I. Will,
S Wipf,
O. Yavas,
K. Yokoya,
M. Yurkov,
A.F. \.Zarnecki,
P. Zerwas,
F Zomer
[show abstract]
[hide abstract]
ABSTRACT: TESLA Technical Design Report, Part VI, Chapter 1: The Photon Collider at TESLA Comment: 102 pages, 41 figures, editor: V. Telnov
08/2001;
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T. Kamps,
DESY Maschinenphysik,
W. Anders,
A. Frahm,
J Knobloch,
O. Kugeler,
A. Neumann, T Quast,
M. Schenk,
M. Schuster,
M. Dirsat,
P. Kneisel,
R. Nietubyc,
T. Rao,
J. Smedley,
J.K. Sekutowicz,
J Teichert,
I. Will
14th International Conference on RF Superconductivity,Berlin,Germany (2009),164.
