Abstract
Recently, a
$$\gamma \gamma $$
γ
γ
collider based on the existing 17.5 GeV linac of the European XFEL has been proposed. High-energy photons will be generated by Compton scattering of laser ...photons with a wavelength of 0.5–1
$${\,\upmu \mathrm m}$$
μ
m
on electrons. Such a photon collider covers the range of invariant masses
$$W_{\gamma \gamma } <12$$
W
γ
γ
<
12
$${\mathrm {\,Ge V\!/}c^2}$$
Ge
V
/
c
2
. The physics program includes spectroscopy of
$$ C $$
C
-even resonances (
c
-,
b
-quarkonia, 4-quark states, glueballs) in various
$$J^P$$
J
P
states. Variable circular and linear polarizations will help in determining the quantum numbers. In this paper, we present a summary of measured and predicted two-photon widths of various resonances in the mass region 3–12
$${\mathrm {\,Ge V\!/}c^2}$$
Ge
V
/
c
2
and investigate the experimental possibility of observing these heavy two-photon resonances under the conditions of a large multi-hadron background. Registration of all final particles is assumed. The minimum values of
$$\varGamma _{\gamma \gamma }(W)$$
Γ
γ
γ
(
W
)
are obtained at which resonances can be detected at a
$$5\sigma $$
5
σ
confidence level in 1 year of operation.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
2.
Overview of the SACLA facility Yabashi, Makina; Tanaka, Hitoshi; Ishikawa, Tetsuya
Journal of synchrotron radiation,
20/May , Volume:
22, Issue:
3
Journal Article
Peer reviewed
Open access
In March 2012, SACLA started user operations of the first compact X‐ray free‐electron laser (XFEL) facility. SACLA has been routinely providing users with stable XFEL light over a wide photon energy ...range from 4 to 15 keV and an ultrafast pulse duration below 10 fs. The facility supports experimental activities in broad fields by offering high‐quality X‐ray optics and diagnostics, as well as reliable multiport charge‐coupled‐device detectors, with flexible experimental configurations. A two‐stage X‐ray focusing system was developed that enables the highest intensity of 1020 W cm−2. Key scientific results published in 2013 and 2014 in diverse fields are reviewed. The main experimental systems developed for these applications are summarized. A perspective on the facility upgrade is presented.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
In the field of beam physics, two frontier topics have taken center stage due to their potential to enable new approaches to discovery in a wide swath of science. These areas are: advanced, high ...gradient acceleration techniques, and x-ray free electron lasers (XFELs). Further, there is intense interest in the marriage of these two fields, with the goal of producing a very compact XFEL. In this context, recent advances in high gradient radio-frequency cryogenic copper structure research have opened the door to the use of surface electric fields between 250 and 500 MV m−1. Such an approach is foreseen to enable a new generation of photoinjectors with six-dimensional beam brightness beyond the current state-of-the-art by well over an order of magnitude. This advance is an essential ingredient enabling an ultra-compact XFEL (UC-XFEL). In addition, one may accelerate these bright beams to GeV scale in less than 10 m. Such an injector, when combined with inverse free electron laser-based bunching techniques can produce multi-kA beams with unprecedented beam quality, quantified by 50 nm-rad normalized emittances. The emittance, we note, is the effective area in transverse phase space (x, p x /m e c) or (y, p y /m e c) occupied by the beam distribution, and it is relevant to achievable beam sizes as well as setting a limit on FEL wavelength. These beams, when injected into innovative, short-period (1-10 mm) undulators uniquely enable UC-XFELs having footprints consistent with university-scale laboratories. We describe the architecture and predicted performance of this novel light source, which promises photon production per pulse of a few percent of existing XFEL sources. We review implementation issues including collective beam effects, compact x-ray optics systems, and other relevant technical challenges. To illustrate the potential of such a light source to fundamentally change the current paradigm of XFELs with their limited access, we examine possible applications in biology, chemistry, materials, atomic physics, industry, and medicine-including the imaging of virus particles-which may profit from this new model of performing XFEL science.
X-ray free-electron lasers (FELs), which amplify light emitted by a relativistic electron beam, are extending nonlinear optical techniques to shorter wavelengths, adding element specificity by ...exciting and probing electronic transitions from core levels. These techniques would benefit tremendously from having a stable FEL source, generating spectrally pure and wavelength-tunable pulses. We show that such requirements can be met by operating the FEL in the so-called echo-enabled harmonic generation (EEHG) configuration. Here, two external conventional lasers are used to precisely tailor the longitudinal phase space of the electron beam before emission of X-rays. We demonstrate high-gain EEHG lasing producing stable, intense, nearly fully coherent pulses at wavelengths as short as 5.9 nm (~211 eV) at the FERMI FEL user facility. Low sensitivity to electron-beam imperfections and observation of stable, narrow-band, coherent emission down to 2.6 nm (~474 eV) make the technique a prime candidate for generating laser-like pulses in the X-ray spectral region, opening the door to multidimensional coherent spectroscopies at short wavelengths.Echo-enabled harmonic generation in a free-electron laser enables 45th harmonic pulses from a 264 nm wavelength seed, yielding 5.9 nm wavelength coherent output.
The European XFEL is a hard X-ray free-electron laser (FEL) based on a high-electron-energy superconducting linear accelerator. The superconducting technology allows for the acceleration of many ...electron bunches within one radio-frequency pulse of the accelerating voltage and, in turn, for the generation of a large number of hard X-ray pulses. We report on the performance of the European XFEL accelerator with up to 5,000 electron bunches per second and demonstrating a full energy of 17.5 GeV. Feedback mechanisms enable stabilization of the electron beam delivery at the FEL undulator in space and time. The measured FEL gain curve at 9.3 keV is in good agreement with predictions for saturated FEL radiation. Hard X-ray lasing was achieved between 7 keV and 14 keV with pulse energies of up to 2.0 mJ. Using the high repetition rate, an FEL beam with 6 W average power was created.The first operation of the European X-ray free-electron laser facility accelerator based on superconducting technology is reported. The maximum electron energy is 17.5 GeV. A laser average power of 6 W is achieved at a photon energy of 9.3 keV.
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FZAB, GEOZS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Recent developments in CrystFEL White, Thomas A.; Mariani, Valerio; Brehm, Wolfgang ...
Journal of applied crystallography,
April 2016, Volume:
49, Issue:
2
Journal Article
Peer reviewed
Open access
CrystFEL is a suite of programs for processing data from `serial crystallography' experiments, which are usually performed using X‐ray free‐electron lasers (FELs) but also increasingly with other ...X‐ray sources. The CrystFEL software suite has been under development since 2009, just before the first hard FEL experiments were performed, and has been significantly updated and improved since then. This article describes the most important improvements which have been made to CrystFEL since the first release version. These changes include the addition of new programs to the suite, the ability to resolve `indexing ambiguities' and several ways to improve the quality of the integrated data by more accurately modelling the underlying diffraction physics.
Developments in the CrystFEL software suite, for processing diffraction data from `serial crystallography' experiments, are described.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The FERMI free-electron lasers Allaria, E.; Badano, L.; Bassanese, S. ...
Journal of synchrotron radiation,
20/May , Volume:
22, Issue:
3
Journal Article
Peer reviewed
Open access
FERMI is a seeded free‐electron laser (FEL) facility located at the Elettra laboratory in Trieste, Italy, and is now in user operation with its first FEL line, FEL‐1, covering the wavelength range ...between 100 and 20 nm. The second FEL line, FEL‐2, a high‐gain harmonic generation double‐stage cascade covering the wavelength range 20–4 nm, has also completed commissioning and the first user call has been recently opened. An overview of the typical operating modes of the facility is presented.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
The Low Density Matter (LDM) beamline has been built as part of the FERMI free‐electron laser (FEL) facility to serve the atomic, molecular and cluster physics community. After the commissioning ...phase, it received the first external users at the end of 2012. The design and characterization of the LDM photon transport system is described, detailing the optical components of the beamline.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
The high peak brilliance and femtosecond pulse duration of X‐ray free‐electron lasers (XFELs) provide new scientific opportunities for experiments in physics, chemistry and biology. In structural ...biology, one of the major applications is serial femtosecond crystallography. The intense XFEL pulse results in the destruction of any exposed microcrystal, making serial data collection mandatory. This requires a high‐throughput serial approach to sample delivery. To this end, a number of such sample‐delivery techniques have been developed, some of which have been ported to synchrotron sources, where they allow convenient low‐dose data collection at room temperature. Here, the current sample‐delivery techniques used at XFEL and synchrotron sources are reviewed, with an emphasis on liquid injection and high‐viscosity extrusion, including their application for time‐resolved experiments. The challenges associated with sample delivery at megahertz repetition‐rate XFELs are also outlined.
Current developments and challenges for serial sample delivery at synchrotrons and X‐ray free‐electron lasers are reviewed, including the new megahertz repetition‐rate machines, with an emphasis on liquid injection and high‐viscosity extrusion.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Radiation damage is still the most limiting factor in obtaining high‐resolution structures of macromolecules in crystallographic experiments at synchrotrons. With the advent of X‐ray free‐electron ...lasers (XFELs) that produce ultrashort and highly intense X‐ray pulses, it became possible to outrun most of the radiation‐damage processes occurring in the sample during exposure to XFEL radiation. Although this is generally the case, several experimental and theoretical studies have indicated that structures from XFELs may not always be radiation‐damage free. This is especially true when higher intensity pulses are used and protein molecules that contain heavy elements in their structures are studied. Here, the radiation‐damage mechanisms that occur in samples exposed to XFEL pulses are summarized, results that show indications of radiation damage are reviewed and methods that can partially overcome it are discussed.
Research in the area of protein crystallography at X‐ray free‐electron laser sources is summarized from the perspective of radiation damage, including its mechanisms and effects, ways to minimize it and a comparison with the damage observable at synchrotrons.
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