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Y Ding,
F-J Decker,
P Emma,
C Feng,
C Field,
J Frisch,
Z Huang,
J Krzywinski, H Loos,
J Welch,
J Wu,
F Zhou
[show abstract]
[hide abstract]
ABSTRACT: We report the first measurements of x-ray single-pulse duration and two-pulse separation at the Linac Coherent Light Source using a cross-correlation technique involving x rays and electrons. An emittance-spoiling foil is adopted as a very simple and effective method to control the output x-ray pulse. A minimum pulse duration of about 3 fs full width at half maximum has been measured together with a controllable pulse separation (delay) between two pulses. This technique provides critical temporal diagnostics for x-ray experiments such as x-ray pump-probe studies.
Physical Review Letters 12/2012; 109(25):254802. · 7.37 Impact Factor
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D Ratner,
A Brachmann,
F J Decker,
Y Ding,
D Dowell,
P Emma,
A Fisher,
J Frisch,
S Gilevich,
Z Huang, [......],
R Iverson,
J Krzywinski, H Loos,
M Messerschmidt,
H D Nuhn,
T Smith,
J Turner,
J Welch,
W White,
J Wu
[show abstract]
[hide abstract]
ABSTRACT: The linac coherent light source (LCLS) is a self-amplified spontaneous emission (SASE) free-electron laser (FEL) operating at fundamental photon energies from 0.5 to 10 keV. Characterization of the higher harmonics present in the FEL beam is important to users, for whom harder x rays can either extend the useful operating wavelength range or increase experimental backgrounds. We present measurements of the power in both the second and third harmonics, and compare the results to expectations from simulations. We also present studies of the transport of harmonics to the users, and the harmonic power as a function of electron beam quality.
Physical Review Special Topics - Accelerators and Beams 06/2011; 14. · 1.52 Impact Factor
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P. Emma,
R. Akre,
J. Arthur,
R. Bionta,
C. Bostedt,
J. Bozek,
A. Brachmann,
P. Bucksbaum,
R. Coffee,
F.-J. Decker, [......],
D. Schultz,
T. Smith,
P. Stefan,
H. Tompkins,
J. Turner,
J. Welch,
W. White,
J. Wu,
G. Yocky,
J. Galayda
[show abstract]
[hide abstract]
ABSTRACT: The recently commissioned Linac Coherent Light Source is an X-ray free-electron laser at the SLAC National Accelerator Laboratory. It produces coherent soft and hard X-rays with peak brightness nearly ten orders of magnitude beyond conventional synchrotron sources and a range of pulse durations from 500 to <10 fs (10−15 s). With these beam characteristics this light source is capable of imaging the structure and dynamics of matter at atomic size and timescales. The facility is now operating at X-ray wavelengths from 22 to 1.2 Å and is presently delivering this high-brilliance beam to a growing array of scientific researchers. We describe the operation and performance of this new ‘fourth-generation light source’.
Nature Photonics 07/2010; 4(9):641-647. · 29.28 Impact Factor
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D Ratner,
A Brachmann,
F J Decker,
Y Ding,
D Dowell,
P Emma,
J Frisch,
S Gilevich,
G Hays,
P Hering, [......],
R Iverson, H Loos,
A Miahnahri,
H D Nuhn,
J Turner,
J Welch,
W White,
J Wu,
D Xiang,
G Yocky
[show abstract]
[hide abstract]
ABSTRACT: We present experimental studies of the gain length and saturation power level from 1.5 nm to 1.5 Angstroms at the Linac Coherent Light Source (LCLS). By disrupting the FEL process with an orbit kick, we are able to measure the X-ray intensity as a function of undulator length. This kick method is cross-checked with the method of removing undulator sections. We also study the FEL-induced electron energy loss after saturation to determine the optimal taper of the undulator K values. The experimental results are compared to theory and simulations. Abstract We present experimental studies of the gain length and saturation power level from 1.5 nm to 1.5 A at the Linac Coherent Light Source (LCLS). By disrupting the FEL pro-cess with an orbit kick, we are able to measure the X-ray in-tensity as a function of undulator length. This kick method is cross-checked with the method of removing undulator sections. We also study the FEL-induced electron energy loss after saturation to determine the optimal taper of the undulator K values. The experimental results are compared to theory and simulations.
09/2009;
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Y Ding,
A Brachmann,
F-J Decker,
D Dowell,
P Emma,
J Frisch,
S Gilevich,
G Hays,
Ph Hering,
Z Huang,
R Iverson, H Loos,
A Miahnahri,
H-D Nuhn,
D Ratner,
J Turner,
J Welch,
W White,
J Wu
[show abstract]
[hide abstract]
ABSTRACT: The Linac Coherent Light Source (LCLS) is an x-ray free-electron laser project presently in a commissioning phase at the SLAC National Accelerator Laboratory. We report here on very low-emittance measurements made at low bunch charge, and a few femtosecond bunch length produced by the LCLS bunch compressors. Start-to-end simulations associated with these beam parameters show the possibilities of generating hundreds of GW at 1.5 A x-ray wavelength and nearly a single longitudinally coherent spike at 1.5 nm with 2-fs duration.
Physical Review Letters 07/2009; 102(25):254801. · 7.37 Impact Factor
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Y Ding,
A Brachmann,
F.-J Decker,
D Dowell,
P Emma,
J Frisch,
S Gilevich,
G Hays,
Ph Hering,
Z Huang,
R Iverson, H Loos,
A Miahnahri,
H.-D Nuhn,
D Ratner,
J Turner,
J Welch,
W White,
J Wu,
C Pellegrini
[show abstract]
[hide abstract]
ABSTRACT: The Linac Coherent Light Source (LCLS) is an x-ray Free-electron Laser (FEL) being commissioned at SLAC. Recent beam measurements have shown that, us-ing the LCLS injector-linac-compressors, the beam emittance is very small at 20 pC. In this paper we perform start-to-end simulations of the entire accelerator including the FEL undulator and study the FEL performance versus the bunch charge. At 20 pC charge, these calculations associated with the measured beam parameters suggest the possibility of generating a longitudinally coherent single x-ray spike with 2-femtosecond (fs) duration at a wavelength of 1.5 nm. At 100 pC charge level, our simulations show an x-ray pulse with 10 femtosecond dura-tion and up to 10 12 photons at a wavelength of 1. A. These results open exciting possibilities for ultrafast science and single shot molecular imaging. Abstract The Linac Coherent Light Source (LCLS) is an x-ray Free-electron Laser (FEL) being commissioned at SLAC. Recent beam measurements have shown that, using the LCLS injector-linac-compressors, the beam emittance is very small at 20 pC. In this paper we perform start-to-end simulations of the entire accelerator including the FEL un-dulator and study the FEL performance versus the bunch charge. At 20 pC charge, these calculations associated with the measured beam parameters suggest the possibility of generating a longitudinally coherent single x-ray spike with 2-femtosecond (fs) duration at a wavelength of 1.5 nm. At 100 pC charge level, our simulations show an x-ray pulse with 10 femtosecond duration and up to 10 12 photons at a wavelength of 1. A. These results open exciting possibili-ties for ultrafast science and single shot molecular imaging.
04/2009;
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J Frisch,
R Akre,
F.-J Decker,
Y Ding,
D Dowell,
P Emma,
S Gilevich,
G Hays,
Ph Hering,
Z Huang, [......], H Loos,
E Medvedko,
A Miahnahri,
H.-D Nuhn,
D Ratner,
S Smith,
J Turner,
J Welch,
W White,
J Wu
04/2008;
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[show abstract]
[hide abstract]
ABSTRACT: The ultra-short bunches of the electron beam for LCLS are generated in two 4-dipole bunch compressors located at energies of 250 MeV and 4.3 GeV. Although an absolute measurement of the bunch length can be done by using a transverse deflecting cavity in an interceptive mode, a non-interceptive single shot method is needed as a relative measurement of the bunch length used in the continuous feedback for beam energy and peak current. We report on the design and implementation of two monitors measuring the integrated power of coherent edge radiation from the last dipole in each chicane.
Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007
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K. Bane,
Y. Ding,
P. Emma,
J. Frisch,
Z. Huang, H. Loos,
F. Sannibale,
K. Sonnad,
G. Stupakov,
J. Wu,
M. Zolotorev,
E. Prat
[show abstract]
[hide abstract]
ABSTRACT: The Linac Coherent Light Source (LCLS) is a SASE X-ray free-electron laser project presently under construction at SLAC [1]. The injector section from RF photocathode gun through first bunch compressor chicane was installed during the fall of 2006. The first bunch compressor is located at 250 MeV and nominally compresses a 1-nC electron bunch from an rms length of about 1 mm to 0.2 mm. Transverse phase space and bunch length diagnostics are located immediately after the chicane. We present preliminary measurements and simulations of the longitudinal and transverse phase space after the chicane in various beam conditions, including extreme compression with micron-scale current spikes.
Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007
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R. Akre,
J. Castro,
Y. Ding,
D. Dowell,
P. Emma,
J. Frisch,
S. Gilevich,
G. Hays,
Z. Hering,
R.I. Huang, [......],
M. Saleski,
J. Schmerge,
D. Schultz,
J. Turner,
J. Welch,
W. White,
J. Wu,
L. Froelich,
T. Limberg,
E. Prat
[show abstract]
[hide abstract]
ABSTRACT: The linac coherent light source (LCLS) is a SASE X- ray free-electron laser (FEL) project presently under construction at SLAC [1]. The injector section, from drive-laser and RF photocathode gun through first bunch compressor chicane, was installed in fall 2006. Initial system commissioning with an electron beam is taking place during the spring and summer of 2007. The second phase of construction, including second bunch compressor and full linac, will begin later, in the fall of 2007. We report here on experience gained during the first phase of machine commissioning, including RF photocathode gun, linac booster section, S-band and X-band RF systems, first bunch compressor, and the various beam diagnostics.
Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007
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D.H. Dowell,
J. Castro,
P. Emma,
J. Frisch,
S. Gilevich,
G. Hays,
P. Hering,
C. Limborg-Deprey, H. Loos,
A. Miahnahri,
W. White
[show abstract]
[hide abstract]
ABSTRACT: Requirements for the LCLS injector drive laser present significant challenges to the design of the system. While progress has been demonstrated in spatial shape, temporal shape,UV generation and rep-rate, a laser that meets all of the LCLS specifications simultaneously has yet to be demonstrated. These challenges are compounded by the stability and reliability requirements. The drive laser and transport system has been installed and tested. We will report on the current operational state of the laser and plans for future improvements.
Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007
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32 nd International Free Electron Laser Conference,Malm\"o,Sweden (2010),147-150.
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H Loos,
R Akre,
A Brachmann,
F.-J Decker,
Y Ding,
D Dowell,
P Emma,
J Frisch,
S Gilevich,
G Hays, [......],
R Iverson,
C Limborg-Deprey,
A Miahnahri,
S Molloy,
H.-D Nuhn,
J Turner,
J Welch,
W White,
J Wu,
Slac Menlo
[show abstract]
[hide abstract]
ABSTRACT: The beam diagnostics in the linac for the Linac Coher-ent Light Source (LCLS) X-ray FEL project at SLAC in-cludes optical transition radiation (OTR) screens for mea-surements of transverse and longitudinal beam properties. We report on observations of coherent light emission from the OTR screens (COTR) at visible wavelengths from the uncompressed and compressed electron beam at various stages in the accelerator.
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D H Dowell,
R Akre,
Y Ding,
P Emma,
J Frisch,
S Gilevich,
G Hays,
Ph Hering,
Z Huang,
R Iverson, [......],
J Schmerge,
J Turner,
J Welch,
W White,
J Wu,
Ca,
L Froelich,
T Limberg,
E Prat,
Hamburg Germany
[show abstract]
[hide abstract]
ABSTRACT: The Linac Coherent Light Source (LCLS) is a SASE x-ray Free-Electron Laser (FEL) project presently under construction at SLAC [1]. The injector section, from drive-laser and RF photocathode gun through first bunch compressor chicane, was installed in fall 2006. Initial system commissioning with an electron beam has recently been completed. The second phase of construction, including second bunch compressor and full linac, is planned for 2008. In this paper, we report experimental results and experience gained during the first phase of machine commissioning. This includes the cathode, drive laser, RF photocathode gun, linac booster section, S-band and X-band RF systems, first bunch compressor, and the various beam diagnostics.
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H.-D Nuhn,
F.-J Decker,
Y Ding,
P Emma,
A Fisher,
J Frisch,
Z Huang,
R Iverson,
J Krzywinski, H Loos,
Y Levashov,
M Messerschmidt,
T Smith,
D F Ratner,
J L Turner,
J J Welch,
Z R Wolf,
J Wu
[show abstract]
[hide abstract]
ABSTRACT: During commissioning of the Linac Coherent Light Source (LCLS) x-ray Free Electron Laser (FEL) at the SLAC National Accelerator Laboratory it was shown that saturation lengths much shorter than the installed length of the undulator line can routinely be achieved [1]. This frees undulator segments that can be used to provide enhanced spectral properties and at the same time, test the concept of FEL Afterburners. In December 2009 a project was initiated to convert undulator segments at the down-beam end of the undulator line into Second Harmonic Afterburners (SHAB) to enhance LCLS radiation levels in the 10 – 20 keV energy range. This is being accomplished by replacement of gap-shims increasing the fixed gaps from 6.8 mm to 9.9 mm, which reduces their K values from 3.50 to 2.25 and makes the segments resonant at the second harmonic of the upstream unmodified undulators. This paper reports experimental results of the commissioning of the SHAB extension to LCLS. Figure 1: LCLS SHAB performance prediction at 14 GeV based on FEL simulations using GENESIS 1.3 for <β x,y >=30 m (standard LCLS undulator lattice) and <β x,y >=15 m. The latter is beyond the present capability of the quadrupole system, which is limited to <β x,y >~22 m at 14 GeV.
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H Loos,
R Akre,
A Brachmann,
R Coffee,
F.-J Decker,
Y Ding,
D Dowell,
S Edstrom,
P Emma,
A Fisher, [......],
D Ratner,
J Rzepiela,
T Smith,
P Stefan,
H Tompkins,
J Turner,
J Welch,
W White,
J Wu,
G Yocky
[show abstract]
[hide abstract]
ABSTRACT: The Linac Coherent Light Source (LCLS) X-ray FEL utilizing the last km of the SLAC linac has been opera-tional since April 2009 and finished its first successful user run last December. The various diagnostics for electron beam properties including beam position monitors, wire scanners, beam profile monitors, and bunch length diagnos-tics are presented as well as diagnostics for the X-ray beam. The low emittance and ultra-short electron beam required for X-ray FEL operation has implications on the transverse and longitudinal diagnostics. The coherence effects of the beam profile monitors and the challenges of measuring fs long bunches are discussed.
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R Akre,
A Brachmann,
F.-J Decker,
Y Ding,
D Dowell,
P Emma,
J Frisch,
S Gilevich,
G Hays,
Ph Hering, [......],
C Limborg-Deprey, H Loos,
S Molloy,
A Miahnahri,
H.-D Nuhn,
D Ratner,
J Turner,
J Welch,
W White,
J Wu
[show abstract]
[hide abstract]
ABSTRACT: The Linac Coherent Light Source (LCLS) is a SASE x-ray Free-Electron Laser (FEL) project under construction at SLAC [1]. The injector section, from drive-laser and RF photocathode gun through the first bunch compressor, was commissioned in the spring and summer of 2007. The second phase of commissioning, including the second bunch compressor and various main linac modifications, was completed in January through August of 2008. We report here on experience gained during this second phase of machine commissioning, including the injector, the first and second bunch compressor stages, the linac up to 14 GeV, and beam stability measurements. The final commissioning phase, including the undulator and the long transport line from the linac, is set to begin in December 2008, with first light expected in July 2009.
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R Akre,
A Brachmann,
F.-J Decker,
Y Ding,
D Dowell,
P Emma,
J Frisch,
S Gilevich,
G Hays,
Ph Hering, [......],
C Limborg-Deprey, H Loos,
S Molloy,
A Miahnahri,
H.-D Nuhn,
D Ratner,
J Turner,
J Welch,
W White,
J Wu
[show abstract]
[hide abstract]
ABSTRACT: The beam stability specifications for the Linac Coherent Light Source (LCLS) Free-Electron Laser (FEL) at Stanford Linear Accelerator Center are critical for X-Ray power, pointing, and timing stability. Studies of the transverse, longitudinal, and intensity stability of the electron beam are presented. Some sources are identified, correlated, and quantified.
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J Welch,
A Brachmann,
F-J Decker,
Y Ding,
P Emma,
A Fisher,
J Frisch,
Z Huang,
R Iverson, H Loos, [......],
D Ratner,
J Turner,
J Wu,
D Xiang,
Menlo Park,
C Usa,
R Bionta,
Llnl Livermore,
Usa H Sinn,
Hamburg Germany
[show abstract]
[hide abstract]
ABSTRACT: We report our first in-situ measurements of relative un-dulator segment K-parameters made at the LCLS. The di-agnostics, calibration, procedure, and early results are de-scribed. Measurement errors and noise are discussed and the outlook for near-term develop presented.
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S. Moeller,
J. Arthur,
A. Brachmann,
R. Coffee,
F.-J. Decker,
Y. Ding,
D. Dowell,
S. Edstrom,
P. Emma,
Y. Feng, [......],
T. McCarville,
D. McMahon,
M. McKernan,
L. Ott,
M. Pivovaroff,
J. Robinson,
D. Ryutov,
S. Shen,
R. Soufli,
G. Pile
[show abstract]
[hide abstract]
ABSTRACT: The LCLS hard X-ray Free Electron Laser at SLAC reported first lasing in April 2009. Since then two successful user runs have been completed at the two soft X-ray stations. The first hard X-ray station has started commissioning in July 2010. Beam diagnostics play an essential role for tuning the machine and delivering the requested beam properties to the users. An overview of the LCLS photon diagnostics will be presented including some selected commissioning results. Plans for future improvements and upgrades will be briefly discussed.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 635(1). · 1.21 Impact Factor
