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The past half a century has seen a revolution in our understanding of how the rapid compression of matter via shock or quasi-isentropic compression operates at the lattice level. Much of this understanding has come about due to the development of short pulse sources of x-rays that provide diffraction patterns on timescales short compared with the duration of the compression pulse to traverse the sample. Such diffraction data has yielded fundamental information on how materials relax, via plastic flow, towards the hydrostatic state, despite the compression process being at heart uniaxial in strain, as well a wealth of information about how materials change polymorphic phase under said compression. It should be noted that these two phenomena are not necessarily separate. Such sources originally included x-ray diodes, but the main ones now used comprise either laser-produced plasmas (LPPs), synchrotrons, or Free Electron Lasers (FELs). Owing to the large laser energies available at several laser facilities world-wide, LPPs have been used to obtain diffraction patterns from condensed matter at extremely high pressures, well into the TPa regime. On the other hand, whilst to date the optical compression drivers situated alongside synchrotrons and FELs are of insufficient capacity to reach the TPa level, the temporal resolution, purity, and signal to noise ratios that can be achieved in the diffraction data provides distinct advantages. Here we provide a brief history of some of the main developments in the field, and offer some perspective on future developments. [ABSTRACT FROM AUTHOR]

The propagation of the Gaussian laser beam through the atmosphere is one of the most important features for military, scientific, industry and medical applications. this paper presents a theoretical study to simulate the effect of turbulence attenuation on propagation of laser beam and calculation of lossy power and divergence beam. A simulation of laser production within the X-ray region showed that the wavelength (0.0985 nm) used in the research could be obtained using the energy of the electron beam of (320 PJ). There are three important parameters in calculating the wavelength in the free electron laser (undulator period, relativistic factor, undulator parameter), and they appear through simulations when the laser power depends greatly on the undulator length and we can dispense with the resonator and increasing the undulator length. The divergence beam was increased with altitude and equals (0.0195003m) in (H= 11km). From the attenuation calculations, the power absorbed (lost) is directly proportional to the radius of the laser beam and inversely proportional to the laser wavelength. From the attenuation calculations, the power absorbed (lost) is directly proportional to the radius of the final laser beam and inversely proportional to the laser wavelength. As for the atmosphere turbulence, it is intense at sea level and decreases with altitude, the structure refractive index C n 2 in MSL equal 3.92 × 10 − 13 m 2 3 and indicates the severe of turbulence. Fried Parameter ro is directly proportional with altitude and (ro=0.7485 μm) in sea level and indicates to severe turbulence and decreases with altitude. Therefore, the attenuation operation and atmospheric turbulence are affected by temperature fluctuations and altitude. [ABSTRACT FROM AUTHOR]

Gaussian beam propagation of the Free Electron Laser (FEL) through the atmosphere is a very important topic for many vital applications in the military, scientific, and medical fields, where laser beam spot size and final power are extremely important requirements in most laser applications. The propagation of a Gaussian laser beam in the atmosphere is subject to attenuation processes that affect the laser beam. From the results, simulations of the free electron laser system showed that an X-ray laser with a wavelength of 0.50418 nm can be produced with an energy beam of 200 PJ. The M2 quality factor will increase with the propagation distance, determining the final laser spot size. As a result of the attenuation processes, there is a slight loss in the final energy of the laser as well as divergence in the laser beam that reaches the target. The amount of attenuation is highly dependent on the density of the atmosphere and the size of the laser spot. When the laser beam propagates in the near-field (less than 20 m) or mid-field (20–100 m) horizontally and vertically at sea level, the values of the attenuation coefficient when propagating in the horizontal direction are greater compared to the propagation in the vertical direction. [ABSTRACT FROM AUTHOR]

TPS 31A beamline utilizing wiggler source W100 is designed for the application of projection X-ray microscopy (PXM) and transmission X-ray microscopy (TXM). The high flux of the wiggler source is benefit for the excellent temporal resolution of images. Nevertheless, the large heat load induces severe thermal-deformation and big slope error of the optics in consequence degrades the uniformity of the images seriously. The vertical collimating mirror (VCM) is the first optical element of this beamline, and the absorbed heat load will be up to 112 W. Its thermal deformations should be well-controlled for optimizing the energy resolution of the double crystal monochromator (DCM) and the image quality. Deliberately, top-side water cooling method was adopted to minimize the thermal deformation of the VCM. The thermal slope error in an optimized top-side water cooled VCM can be reaches less than 0.8 µrad of magnitude compared to a non-optimized VCM. [ABSTRACT FROM AUTHOR]

As a result of scientific research, a multicomponent compound was synthesized containing polymers with a system of conjugated bonds (a group of unsaturated polymers with alternating single, double and triple bonds) and a catalyst (selected from the group of organic complexes of metal halides of variable valence), capable of initiating phase transitions in polymers under certain conditions. transitions of the first or second order, accompanied by the emission of free electrons. The technical solutions proposed for protection relate to electrical engineering, in particular to electrical devices designed to generate electric current and transfer it to the consumer circuit. The proposed technology is based on the accumulation of free electrons that create a volumetric negative charge. The element of the device in which the formation and accumulation of free electrons occurs, as a rule, is called a module. Combining modules into a specific system allows you to form a device (ESA) for the accumulation and transmission of current to the consumer. An analysis of information on classes related to the means of obtaining additional energy supply to the consumer showed that the majority uses the principle of energy storage in special devices or circuits. Currently, pilot batches of devices are being produced to order on a contractual basis. Pilot production is functioning and includes an assembly conveyor, a laboratory section for compound synthesis and a quality control section. [ABSTRACT FROM AUTHOR]

In recent years, lasers have become the first in the medical field and its applications Because of its unique capabilities, high efficiency, and fast and accurate treatment. In this paper, a laser system was designed with high efficiency for the free electron laser, which is characterized by this type, which gives all wavelengths from long to short by controlling parameters to obtain the appropriate wavelength required in the work. This system was designed using an execuTABLE program Matlab 2019 depending on the equations of the free electron laser. Where all appropriate wavelengths equivalent to body tissues, blood and organs were obtained, and these lengths can penetrate the body tissues and organs without damaging them. In addition, by studying the optical properties of the tissue, the wavelength was chosen the wavelength equivalent to it was chosen, and by controlling the energy, field strength, wavelength of the electron, or other parameters that control wavelength change, it can be relied upon to obtain the best values for wavelength, exposure time and pulse energy suitable for laser therapy. [ABSTRACT FROM AUTHOR]

Nowadays, the development of laser devices in the medical field has become large and highly efficient compared to regular surgery. The aim of this work is to design a laser technology system to remove and break up blood clots in the human body, especially in the sensitive areas that pose a threat to his life. This system is characterized by being environmentally friendly, has no side effects on the human body, and is economically inexpensive. The program of Matlab 2019 was used to create an executable program to simulate a pulse system for a new model which is Free Electron Laser (FEL) in any range of wavelength and in this work it is in the ultraviolet range and the electrons energy about 450 MeV and wavelength equal 22.5 nm to remove these clots by breaking the bonds connecting the clots components. The energy, which gives this wavelength is among the short wavelengths that approximate in its action from the magnetic resonance. This program consists of Specific parameters which a simulation to obtain the best values for wavelength, exposure time and pulse energy. [ABSTRACT FROM AUTHOR]

Due to the difficulty in manufacturing the resonator mirrors to produce a laser beam within the X-ray wavelength range, as well as to eliminate the losses associated with the production of the laser beam inside the resonator. Therefore, it has been proposed to generate short-wavelength a free electron laser radiation pass through a long undulator without a resonator, called self-amplified spontaneous emission (SASE). In this paper, a laser system was designed and simulated using Matlab program. A program has been created that contains many parameters. Through the results obtained for the values of power and wavelength in the case of the presence and absence of the resonator, it was concluded that it is possible to dispense with the resonator, and to obtain the same values of output power and wavelength by increasing the undulator length or the electron energy, to compensate for the absence of the resonator, which leads to an increase in the number of generated photons, thus an amplification of the laser radiation and output power. [ABSTRACT FROM AUTHOR]

One of the most important problems fronting the design of optical detectors that operate at the high power; was the inability to withstand the high temperature caused by the interaction between the material of the detector and the high-power laser beam. In this paper, the goal is to design and study a high-power laser detector. Which is bases on the principle of the internal photoelectric effect and is made of a material with a high melting point to prevent its collapse and destruction when high-power laser radiation falls on it. By using specific techniques to reduce the intensity and energy of laser radiation by simulation using the Matlab program (2019), which includes several parameters to calculate the highest energy borne, response and efficiency of the detector. To achieve this, a high-power laser system based on the free electron laser will be design and simulated using the Matlab program (2019), which includes several parameters to calculate the energy and wavelength of the laser outside, in addition to calculating the attenuation factors that occur when the laser signal interacts with the atmosphere. Through the results obtained, it was observed the energy (HPFEL) beam depends on the laser beam radius and the atmosphere density when the (HPFEL) beam propagation through the atmosphere. The photoresponsivity (PR) with the external quantum efficiency (EQE) for the (MSM) photodetector is directly proportional with disk aperture area. [ABSTRACT FROM AUTHOR]

We demonstrate the capabilities of ion-beam lithography (IBL) for the manufacturing of the X-ray refractive micro-optics. With the help of IBL, the hardest of current materials - diamond - was milled, and microscale diamond lenses were produced. Lenses have a rotationally parabolic profile with radii of parabola apexes less than 5 µm. As has been confirmed with SEM and AFM, shape profile errors of fabricated lenses were<200 nm, while the surface roughness was estimated to be 50 nm. Single lenses were stacked in the CRL within one technological process with high alignment precision. [ABSTRACT FROM AUTHOR]

Surface plasmon resonance (SPR) microscopy is one of the most sensitive label-free microscopy methods, however with low lateral resolution. This drawback is primarily caused by the fact that surface plasmon polaritons (SPPs) excited by terahertz (THz) radiation propagate macro distances (about ∼100 1) from their excitation spot, thereby blurring the observed region, like with a scattering medium. To eliminate this disadvantage, we adapt a method known as ghost imaging (GI), which is notable for its tolerance to environmental aberrations between the object and camera. We propose an optical scheme of SPR microscopy for the THz range with an additional optical arm to implement the classical GI and provide an analysis of factors affecting the image quality. To implement the classical GI in the THz range, we propose to use the Novosibirsk free electron laser (NovoFEL) as a THz radiation source. The high beam power of the NovoFEL provides a speckle structure with a pronounced profile, which is required to achieve a high level of contrast in the obtained image. Moreover, the large coherence length of the NovoFEL radiation is necessary to ensure a large degree of correlation between the beams emerging from the beam splitter, which allows reconstructing an image with a lower noise level. [ABSTRACT FROM AUTHOR]

The elements of beam-shaping refractive optics such as axicon lenses and interferometers based on parabolic refractive lenses are considered. A theoretical analysis of the formation of the beam by the axicons and interferometers was carried out and corresponding computer simulations were performed. The beam-shaping optical elements were experimentally tested at the European Synchrotron Radiation Facility (ESRF). Experimentally recorded images of shaped beams are in a good agreement with computer calculations. Several approaches to beam conditioning and source diagnostics were proposed. Future possible coherence-related applications of the beam-shaping optics are discussed. [ABSTRACT FROM AUTHOR]

In 1990s, the emergence of the 3rd generation synchrotron user facilities equipped with undulator sources, stimulated pioneering works on interaction of coherent X-ray beams with matter, resulted in the development of X-ray photon correlation spectroscopy (XPCS) technique capable to probe nanoscale fluctuations up to kHz frequencies using dynamics of speckle pattern given by scattering of coherent X-ray beam from the sample. More recently (and highly aided by the development of modern high-throughput data analysis algorithms), coherent X-ray diffraction imaging (CXDI), also known as lensless imaging, revolutionized the field of X-ray microscopy, finally bringing users the possibility of non-destructive 2D and 3D imaging of complex structures with unprecedented −10 nm resolution. However, strict requirements to transverse coherence of X-ray probe put serious limits on further development of CXDI-based techniques at the 3rd generation facilities, where coherent flux after spatial filtering becomes unacceptably small at energies above -20 keV. At the same time, the latter was used as one of the strongest arguments of the user community for push towards construction of multibend-achromat-based 4th generation of storage rings with ultra-low emittance. Whereas at the 3rd generation facilities the phase volume of undulator source was dominated by electron beam emittance with negligible influence of other factors, the estimation and minimization of undulator source phase volume at 4 th generation facilities requires more elaborate approach taking into account electron beam energy spread and matching of phase-space ellipses between electron and X-ray beams. Here we present estimations of coherent flux at different energies available for future users of ultra-low-emittance SKIF storage ring (to be commissioned in 2023) and discuss ways of its optimization. [ABSTRACT FROM AUTHOR]

The propagation length of surface plasmon polaritons (SPPs) increases with wavelength, which makes it possible to use radiation from the far-infrared and terahertz ranges to create communication devices employing SPPs as carriers of information. In this paper, we consider methods for implementing the multiplex transmission of information along cylindrical conductors using a combination of SPPs with orbital angular momentum and present experimental setups for the experiments on the Novosibirsk free electron laser. [ABSTRACT FROM AUTHOR]

The X-band Electron Paramagnetic Resonance (EPR) spectroscopy endstation at the Novosibirsk Free Electron Laser (NovoFEL) facility is capable for steady-state (CW) EPR and time-resolved (TR) continuous wave EPR experiments. Recently several upgrades in experimental hardware and software have been done, aiming to more productively use the time of experimental session and to increase the control of experimental parameters during the session. Firstly, we installed detectors with different time resolution for tracking radiation produced by NovoFEL. Secondly, on the basic of fsc2 program, we implemented a possibility of a simultaneous use of two oscilloscopes, configured at different timescale and/or sensitivity. Finally, we developed software for on-the-fly CW and TR experimental data viewing and treatment. [ABSTRACT FROM AUTHOR]

The results of investigations of relaxation processes of donor bound electrons in the germanium doped by arsenic at cryogenic temperatures are presented. The lifetimes of p-type excited states of a donor were measured by pump-probe technique utilizing THz radiation from free-electron laser NovoFEL. The uniaxial stress along [111] axis was applied to the crystal to modify the energy spectrum of the impurity and intervalley relaxation processes. The analysis of experimental for p-type excited states allows to get the upper limit for the relaxation time of lowest 1s excited state. The comparison of obtained experimental results with the theoretical estimates for the interaction with TA phonons indicates on the enhancement of the interaction with the phonons having wavenumbers corresponding to the flat part of the dispersion. [ABSTRACT FROM AUTHOR]

Effect of external longitudinal magnetic field on the optical Free Induction Decay (FID) from a free radical was observed for the first time. The experiments were performed on the rotational transition of hydroxyl radical OH (2Π3/2(J=1) ← 2Π3/2(J=0) at 83.8 cm-1) using the Terahertz Free Electron Laser. In contrast to the results of the experiments with a stable paramagnetic molecule NO, the observed effect of external magnetic field on the Free Induction Decay from hydroxyl radicals is more complicated. A longitudinal magnetic field leads to rotation of the polarization plane of the FID radiation, as well as to additional modulation of the signal intensity. The angle of rotation of the polarization plane is large, in agreement with the theoretical predictions. The observed FID kinetics in the time domain are in semi-quantitative agreement with the modeling. This observation opens an opportunity for selective detection by polarization discrimination of weak signals of short-lived reactive paramagnetic free radicals from overwhelming signals that originate from stable non-paramagnetic species. [ABSTRACT FROM AUTHOR]

A review is given of recent experiments in the field of terahertz optics conducted on the Novosibirsk free electron laser (NovoFEL). The NovoFEL facility configuration is briefly described, and radiation characteristics of the three laser systems of the facility are presented. Considerable attention has been paid to the development and testing of quasi-optical elements designed for this range and methods to produce high-power beams of terahertz radiation with a given mode composition. The use of terahertz radiation in the spectroscopy of gases and semiconductors and generation and research on surface plasmon polaritons, as well as applying the latter in surface study and communication applications, are described. [ABSTRACT FROM AUTHOR]

The "Electronic structure" beamline is dedicated for realization different photoelectron spectroscopy application in the SKIF project, requires intense photon flux in the soft X-ray and VUV ranges (10 - 2000 eV). The generation of the undulator radiation in this range is very problematic for electron beams with 3 GeV energy. For keeping the opportunity to cover whole range, the special undulator design with possibility doubling of the period was proposed. The commutation of the coils groups provides change the undulator period from 10 to 20 cm with keeping the amplitude magnetic field (0.5 T). The undulator mode (5 cm period) gives a big flux for high energy edge of the range and the wiggler mode (with period 20 cm) provides the sufficient number of the photons for soft region (down to 10 eV). Some details of the undulator design are presented in the report. [ABSTRACT FROM AUTHOR]

The Free Electron Laser (FEL) based on multi-turn microtron-recuperator is currently operating in Novosibirsk. For successful operation of the facility, a specialized control system was developed. The software part of this system consists of a set of different program modules. For ensuring program connection between a client and server parts of the control software, the Channel Access protocol from the EPICS framework was employed. Features and examples of using this protocol without utilizing the whole EPICS system are described in this article. [ABSTRACT FROM AUTHOR]

The high-power Free Electron Laser (FEL) based on a multi-turn microtron-recuperator is currently operating in Novosibirsk [1]. The radiation of the FEL is used for carrying out experiments in different areas of physics, biology, and chemistry. The radiation is transported to all user stations using one transportation system, referred to as the "radiation optical channel". To ensure radiation transportation to the required user station, this optical channel contains a set of special mechanical units (mirrors and shutters). The states of all these units determine the track of radiation propagation from its source to the required user station. [ABSTRACT FROM AUTHOR]

An electron outcoupling scheme was proposed for the high power FELs with optical cavities to avoid the power limitation because of overheating of the reflecting mirrors. This can be realized if the major part of radiation power is emitted at an angle to the optical axis. For this, the electron beam should be bunched and then slightly rotated in an undulator of the FEL. At the NovoFEL facility, the electron outcoupling system is installed on the third FEL, based on the multi-turn energy recovery linac. It consists of three undulators, dipole correctors, and two quadrupole lenses assembled between them. There are two different configurations of the system, with electrons deflected in either the second or the third undulator. The electron beam dynamics calculations, current experimental results, and planned experiments are discussed. [ABSTRACT FROM AUTHOR]

The hyperfine spectral structure of radiation−laser modes of the Novosibirsk terahertz free electron laser (NovoFEL) has been measured in two its main operating regimes: resonance unstable regime with maximum output power and stabilized regime with maximum spectral power. The monochromaticity of the mode structure is shown to be practically independent of the laser operating regime and reaches a value of 2·10−8. The mode composition weakly depends on the operating regime for a well aligned electron beam and consists of many longitudinal TEMq00modes (supermode). In the case of a poorly aligned electron beam, transverse modes of the optical cavity are also excited; its intensities strongly increase in the resonance regime. [ABSTRACT FROM AUTHOR]

The Novosibirsk FEL facility includes three FELs operating in the terahertz, far-, and mid- infrared spectral ranges. It has rather long history, but its potential has not been fully revealed so far. The first FEL of this facility has been operating for users of terahertz radiation since 2004. It remains the world's most powerful sources of coherent narrow- band radiation in its wavelength range (90 – 340 µm). The second FEL was commissioned in 2009. Now it operates in the range of 35 – 80 µm, but we plan to replace its undulator soon with a new one, and its short wavelength boundary will be shifted down to 15 µm. The third FEL was commissioned in 2015 to cover the wavelength range of 5 – 20 µm. Its undulator comprises three separate sections. Such lattice is suited very well to demonstrate the new off-mirror way of radiation outcoupling in an FEL oscillator (so called electron outcoupling), which we also plan for near future. We also intend to improve the accelerator injection system. As a result, the average electron beam current and consequently the radiation power of all the three FELs will increase. In this paper, we present an overview of the facility and discuss our recent achievements and future plans. [ABSTRACT FROM AUTHOR]

Fast deformations in the quartz crystals during shock compression process have been investigated with two time-resolved methods of in-situ diffractions by x-ray free electron laser (XFEL) and large-scale molecular dynamic (MD) simulations in order to get insights in planar deformation feature (PDF) mechanism. PDFs in quartz provide strong evidence for impact and are used to estimate the impact conditions. The present experimental results on X-cut and Y-cut quartz single crystals at pressures below phase transition indicate ideal uniaxial compression and rotation of fractured grains to a direction to heat up locally due to dispersed particle velocity distribution in the dynamic movement. This could explain the observed disordering at given planes, as supported by the MD simulations. [ABSTRACT FROM AUTHOR]

In this paper we have solved gain for optical klystron free electron laser using Madey's Theorem.This paper has calculations that includes the effects of length mismatch of the two undulator sections of the klystron configuration. [ABSTRACT FROM AUTHOR]

At present, several problems and challenges have arisen as a result of human population growth and technological development, including global warming, water shortages and drought, especially in arid zones characterized by high temperatures. The low rainfall leads to increased drought and desertification, which has a negative impact on human life. In this study, a new laser technique was proposed to create rain in the atmosphere. Artificial rain can be formed by the proper energy of the laser pulse that stimulates a series of chemical and physical reactions in the clouds to obtain the appropriate rain drops. This technique is based on the use of a free electron beam with suitable energy and adaptable to the weather conditions by changing the wavelength and intensity of the laser beam and the duration of the pulse, ensuring that water droplets of sufficient size to fall. [ABSTRACT FROM AUTHOR]

Free Electron Laser with tunable wavelength and high peak power based on electron accelerators can be produced in oscillator mode (O-FEL) including optical cavity system. In this study, optimization of the main parameters of undulator magnets U35 and U110 of TARLA Oscillator FEL facility are optimized to obtain FEL beams in 3 - 250 micron wavelengths. The types and materials of undulator magnets are defined and magnetic field patterns are obtained by RADIA software. The bandwidth of the FEL beams are defined and the parameter optimization required for maximum gain is done and the maximum deflection angle of electron beam in undulator magnets are defined. As a result, based on defined U35 and U110 undulators parameters, the wavelength, energy, peak and average photon fluxes and brightness, gain and lost percentages, peak and average powers of proposed FEL beams are given. [ABSTRACT FROM AUTHOR]

The volume structure of nanocomposites obtained by laser printing from water-collagen dispersions of carbon nanofibers was studied using X-ray microtomography. For the preparation of dispersions, ultrasonic homogenization methods were used. The concentration of the components was: bovine collagen - 1 wt.%, nanofibres - 0.01 wt.% and 0.1 wt.%. The experiments were carried out at a voltage on the cathode of an x-ray tube ~ 30 kV, current strength - 300 mA; the number of projections - 3000 at the angle of rotation - 0.1º. The porosity of the composites ranged from 25 to 35%. Closed pore spaces were mainly observed in the structure of composites (28%). The pore size (16–23 μm) depended on the size of the protein conglomerates. Using the same water-collagen dispersion of carbon nanofibers, a coating was formed on 2.5 mm wide polymer tapes, which were implanted by pressfit technique into a channel formed in the cancellous bone of laboratory animals. To study the structural reaction of the bone, a three-dimensional visualization of the bone canal was carried out at different observation times. The results of the X-ray study showed that after implantation, there are processes that reflect the osteoconductive properties of the composite. [ABSTRACT FROM AUTHOR]

For real time observations of electron motion inside atoms, molecules and solids via pump-probe type of experiments, a few cycle infrared optical laser pulse is used initially as a pump to excite the electron dynamics and an attosecond pulse is used as a probe. To carry out these experiments, such shortest photon pulse needs to be develop. In free electron laser, a pulse of 270 attosecond full-width half maximum (FWHM) duration at 1 nm radiation wavelength based on our proposed single current spike scheme [1], is shown in simulations. According to the scheme, one current spike with good contrast ratio in an electron bunch is repeatedly used to amplify the seed radiation spike to a terawatt (TW) level of power. In our preliminary simulation for soft X-ray case, initial electron-beam energy spread is lower than 0.1%. However, for the realistic simulation, later stages electron-beam degradation due to the repeated use of a single spike should be taken into account. [ABSTRACT FROM AUTHOR]

An amplitude modulated laser obliquely incident on a metal film of ultrathin size deposited on a semiconductor surface, is found to give a modulated frequency terahertz (THz) surface plasmons. The THz surface plasmon field found to falls off away from the metal film both inside the semiconductor and in the free space also. The free electrons in the thin film experience a ponderomotive force which leads to excitation ofthe THz surface plasma wave (SPW) at the modulation frequency. The ratio of THz wave field to the laser field fall off the order of 10-1 at the laser intensity of 5x1012 W/cm². At the higher frequency, the efficiency falls off due to the weak coupling of SPW. [ABSTRACT FROM AUTHOR]

The AIP Proceedings article template has many predefined paragraph styles for you to use/apply as you write your paper. To format your abstract, use the Microsoft Word template style: Abstract. Each paper must include an abstract. Begin the abstract with the word “Abstract” followed by a period in bold font, and then continue with a normal 9 point font. [ABSTRACT FROM AUTHOR]

Modern photon science performed at high repetition rate free-electron laser (FEL) facilities and beyond relies on 2D pixel detectors operating at increasing frequencies (towards 100 kHz at LCLS-II) and producing rapidly increasing amounts of data (towards TB/s). This data must be rapidly stored for offline analysis and summarized in real time for online feedback to the scientists. While at LCLS all raw data has been stored, at LCLS-II this would lead to a prohibitive cost; instead, enabling real time processing of pixel detector data (dark, gain, common mode, background, charge summing, subpixel position, photon counting, data summarization) allows reducing the size and cost of online processing, offline processing and storage by orders of magnitude while preserving full photon information. This could be achieved by taking advantage of the compressibility of sparse data typical for LCLS-II applications. Faced with a similar big data challenge a decade ago, computer vision stimulated revolutionary advances in machine learning hardware and software. We investigated if these developments are useful in the field of data processing for high speed pixel detectors and found that typical deep learning models and autoencoder architectures failed to yield useful noise reduction while preserving full photon information, presumably because of the very different statistics and feature sets in computer vision and radiation imaging. However, the raw performance of modern frameworks like Tensorflow inspired us to redesign in Tensorflow mathematically equivalent versions of the state-of-the-art, “classical” algorithms used at LCLS. The novel Tensorflow models resulted in elegant, compact and hardware agnostic code, gaining 1 to 2 orders of magnitude faster processing on an inexpensive consumer GPU, reducing by 3 orders of magnitude the projected cost of online analysis and compression without photon loss at LCLS-II. The novel Tensorflow models also enabled ongoing development of a pipelined hardware system expected to yield an additional 3 to 4 orders of magnitude speedup, necessary for meeting the data acquisition and storage requirements at LCLS-II, potentially enabling acquiring every single FEL pulse at full speed. Computer vision a decade ago was dominated by hand-crafted filters; their structure inspired the deep learning revolution resulting in modern deep convolutional networks; similarly, our novel Tensorflow filters provide inspiration for designing future deep learning models for ultrafast and efficient processing and classification of pixel detector images at FEL facilities. [ABSTRACT FROM AUTHOR]

This work reports on the recent activities carried out by the Detector and Instrumentation Laboratory of Elettra Sincrotrone Trieste. Since both the Elettra synchrotron and the Fermi free electron laser are generating photons in the low to medium x-ray energy range from some eV to tenths of keV the activities of the detector and instrumentation laboratory focuses on spectroscopic and imaging photon detectors, which feature high quantum efficiency from below the carbon edge and are operated also in UHV environments. Special focus will be drawn on custom made monolithic and multi element silicon drift detectors for the Twinmic and the XRF beam line at Elettra. Regarding low energy imaging detectors the PERCIVAL CMOS (‘Pixelated Energy Resolving CMOS Imager, Versatile and Large’) will be discussed which is currently being developed by a collaboration of DESY, RAL, Elettra, PAL and DLS to address the need for this type of detectors for free electron lasers in the soft X-ray regime. The majorities of Elettra’s soft x-ray beam lines are employing fast and spatially resolving electron detectors and their associated readout electronics, which have been developed in-house and have been tailored to the specific needs of the respective beam line. In addition devices for in situ beam diagnostics and dose monitoring for synchrotron radiation and FEL beams have been developed and are operated on a daily basis. Moreover, some recent results in basic research on room temperature semiconductors will be discussed. It is noteworthy that Elettra Sincrotrone Trieste through its Industrial Liaison Office commercializes many of these devices and the associated read-out electronics. In this presentation an overview of these devices and their application to specific scientific applications will be given and in view of upgrade programs future directions will be discussed. [ABSTRACT FROM AUTHOR]

ePix10K is a hybrid pixel detector developed at SLAC for demanding free-electron laser (FEL) applications, providing an ultrahigh dynamic range (245 eV to 88 MeV) through gain auto-ranging. It has three gain modes (high, medium and low) and two auto-ranging modes (high-to-low and medium-to-low). The first ePix10K cameras are built around modules consisting of a sensor flip-chip bonded to 4 ASICs, resulting in 352 × 384 pixels of 100 µm x 100 µm each. We present results from extensive testing of three ePix10K cameras with FEL beams at LCLS, resulting in a measured noise floor of 245 eV rms, or 67 e− equivalent noise charge (ENC), and a range of 11 000 photons at 8 keV. We demonstrate the linearity of the response in various gain combinations: fixed high, fixed medium, fixed low, auto-ranging high to low, and auto-ranging medium-to-low, while maintaining a low noise (well within the counting statistics), a very low cross-talk, perfect saturation response at fluxes up to 900 times the maximum range, and acquisition rates of up to 480 Hz. Finally, we present examples of high dynamic range x-ray imaging spanning more than 4 orders of magnitude dynamic range (from a single photon to 11 000 photons/pixel/pulse at 8 keV). Achieving this high performance with only one auto-ranging switch leads to relatively simple calibration and reconstruction procedures. The low noise levels allow usage with long integration times at non-FEL sources. ePix10K cameras leverage the advantages of hybrid pixel detectors with high production yield and good availability, minimize development complexity through sharing the hardware, software and DAQ development with all other versions of ePix cameras, while providing an upgrade path to 5 kHz, 25 kHz and 100 kHz in three steps over the next few years, matching the LCLS-II requirements. [ABSTRACT FROM AUTHOR]

In this paper, we are presenting the Percival detector, a monolithic CMOS Imager for detection of soft x-rays in Synchrotron Rings and Free Electron Lasers. The imager consists in a 2D array of many (2M) small (27um pitch) pixels, without dead or blind zones in the imaging area. The imager achieves low noise and high dynamic range by means of an adaptive-gain in-pixel circuitry, that has been validated on prototypes. The imager features on-chip Analogue-to-Digital conversion to 12+1 bits, and has a readout speed which is compatible with most of Free Electron Laser Facilities. For direct detection of low-energy x-rays, the imager is back-illuminated and post-processed to achieve 100% fill factor. [ABSTRACT FROM AUTHOR]

The Paul Scherrer Institut is currently constructing Athos, its second Free Electron Laser with a photon energy range from 250 eV to 1900 eV and pulse energies up to 8 mJ. A single soft X-ray beamline is attached to the undulator section and distributes the radiation into three branches. The beamline design is based on a variable line space spherical grating monochromator with a grating chamber and two retractable distribution mirrors. An achromatic focusing with individual KB-mirror systems downstream of the exit slits focus the beam to the endstations. The stations can operate alternatively without interfering with each other. [ABSTRACT FROM AUTHOR]

Precise spectral characterization of every pulse is required in many x-ray free-electron laser (XFEL) experiments due to the fluctuating spectral content of self-amplified spontaneous emission (SASE) beams. Bent single-crystal spectrometers can provide suffcient spectral resolution to resolve the SASE spikes while also covering the full SASE bandwidth. However, strain and stresses due to the strong bending may affect the intrinsic diffraction properties of the crystal significantly and thus affect the spectral resolution of the device. This paper experimentally investigates the intrinsic diffraction properties of a strongly bent single-crystal diamond spectrometer to be implemented at the European XFEL and compares with theoretical calculations. [ABSTRACT FROM AUTHOR]

Free Electron Lasers provide unique opportunities in investigating ultrafast atomic-scale dynamics using X-ray Pump Xray Probe and two-pulse X-ray Speckle Visibility Spectroscopy techniques. However the performance of these techniques critically relies on maintaining the spatial overlap between the two beams at the sample location while adjusting the temporal separation between the two pulses. This presents major challenges for realizing hard X-ray split-delay optics, i.e an optical arrangement capable of generating two X-ray pulses separated in time from a single X-ray pulse. More specifically, it translates into nanoradianscale angular precision requirements. We present here a hard X-ray split-delay optics concept using 4 channelcut crystals, where the beam path length difference can be adjusted by the linear translation of two crystals having non-parallel gaps. Having two Bragg reflections from the same monolithic crystal in the opposite direction cancels positioning errors from underlying stages. As a result, this concept has lower motion precision requirements on the hardware, and yet leads to significantly higher output beam angular stability. We present a case study for this concept that covers an energy range from 7 to 12 keV and provides a delay range from -3 to 10 ps at 9 keV. [ABSTRACT FROM AUTHOR]

As the linac-based X-ray FEL oscillator is actively pursued recently, feasibility of a storage ring based X-ray FEL oscillator is examined. Conditions of the required storage ring parameters such as beam emittance and machine parameters are investigated. Also, the performance and advantages and disadvantages of a storage ring based X-ray FEL oscillator is compared with those of other X-ray FEL sources. [ABSTRACT FROM AUTHOR]

Knowledge of different properties of the radiation from X-ray FEL is very important for planning experiments. An understanding of such properties can come from start-to-end simulations of experiments: modern FEL simulation allows to reliably predict the output radiation pulses from X-ray FEL.We present a web accessible XFEL photon pulses simulation database showing data calculated with the FAST simulation framework. [ABSTRACT FROM AUTHOR]

Since the laser invention [1, 2], the advent of Free Electron Lasers (FEL) [3, 4] in the X-ray domain half a century later, has opened new areas for matter investigation with higher temporal resolution. In parallel, the development of laser plasma acceleration (LPA) [5] that delivers today several GeV beam acceleration [6] in a short distance appears also very promising. The qualification of the LPA for FEL application can thus be viewed as an important challenge [7]. Nevertheless, present LPA electron beam parameters (e. g. energy spread and beam divergence) do not meet conventional accelerator state-of-the-art performance and FEL application requires a specific beam handling. In such a prospect, the COXINEL beam manipulation line [8, 9] using variable permanent magnet quadrupoles for emittance growth mitigation and de-mixing chicane for the energy spread handling developed at SOLEIL has been installed for using electrons produced with an intense laser of Laboratoire d’Optique Appliquee (LOA). ´ Strategies for controlling electron beam position and dispersion have been elaborated and demonstrated [10]. Finally, undulator spontaneous emission has been measured at the end of the line. [ABSTRACT FROM AUTHOR]

Development of past and future light sources for synchrotron radiation research is discussed. Starting with the development of 3rd generation sources, the development of X-ray free electron lasers (XFELs) and new generation storage rings with a multi-bend-achromat lattice configuration is discussed. One future ideal form could be the combination of a pulsed X-ray free electron laser (XFEL) featuring both high peak brilliance and a reasonably high (∼10 kHz) repetition rate, with a CW XFEL offering both time-space coherence and moderate average brilliance. [ABSTRACT FROM AUTHOR]

Hard X-ray Free Electron Lasers (XFEL) generate intense coherent X-ray beams by passing electrons through very long periodic magnet structures, which extend over hundreds of meters. The SASE1 and SASE2 undulator systems of the European XFEL consist of 35 segments with variable gap planar undulators which are initially tuned to precise onaxis magnetic field strengths in a magnetic measurement lab to keep a quality parameter, the K-value variation from segment to segment below the pierce parameter. After tunnel installation only photon based methods can determine the K-values of undulator segments with a similar accuracy. The synchrotron radiation from single or a few segments can be spectrally filtered by a dedicated crystal monochromator (K-monochromator) and recorded with either a point detector such as a photo diode or with an imager that provides 2D information, tuned for high sensitivity to detect low photon densities from distant single undulator segments. This instrumentation is applied for electron orbit analysis and optimization, and adjustment of individual undulators in terms of their central magnetic axis with respect to the electron beam. Single undulator segments were analyzed by scanning the monochromator crystal angle and detecting the steepest slope of a photo diode signal. Alternatively in the "electron-kick” method, an imager recorded the two radiation cones of electrons passing through one undulator segment, being kicked laterally and radiating a second time in the next downstream undulator. [ABSTRACT FROM AUTHOR]

SwissFEL is a free electron laser at the Paul Scherrer Institut in Switzerland, which became operational by the end of 2017. Initially, it will host two undulators ARAMIS and ATHOS. The former is operational and generating tender to hard x-rays (2 to 12 keV), whilst the latter is in the process of being installed and will provide soft x-rays ranging from 0.2 to 2 keV. Each undulator will eventually serve three different endstations. Recent Genesis [1] simulations have shown that the ATHOS branch can operate in a high-power mode, which will increase the photon pulse energy by one order of magnitude to 8.1 mJ at 250 eV. This will lead to peak beam intensities inside the frontend, which will damage any normal incidence absorber. To overcome this issue a photon beam diffusor is proposed in this paper. At the core of this instrument is a bent rod, which is positioned at a grazing angle relative to the incident beam, so that it acts like a defocussing mirror, reflecting most of the incident power and increasing the divergence of the reflected beam. Due to the increased divergence, the beam diameter is increased by a factor of 10 after propagating over a few meters, thus reducing the peak intensity by a factor of 100 to a level, which can be safely absorbed by a normal incidence absorber. [ABSTRACT FROM AUTHOR]

The European X-ray Free Electron Laser (European XFEL) is a new user facility in the metropolitan area of Hamburg, Germany. It offers ultra-short (femtosecond) and intense (GigaWatt) transversely coherent x-ray laser beams in the soft to hard x-ray domain at MHz repetition rate. Up to 2700 pulses per train will be delivered at 10 Hz train repetition rate. The x-ray diagnostics [1-4] serves the electron machine to achieve lasing by Self-Amplified Spontaneous Emission (SASE), supports the SASE tuning, and assists to align and commission the photon beam transport. Finally, it delivers non-invasive online beam diagnostic data to the users at the experimental end-stations. In May 2017 the first undulator beamline, SASE1, was successfully commissioned with beam, and First Lasing was detected. This presentation describes the contribution of photon diagnostics during the distinct commissioning phases: Pre-beam checkout, first light from the bending magnets, x-rays from single undulator segments, SASE tuning with many undulator segments, First Lasing, optics alignment for FEL beam transport through the tunnel up to the experimental hutches, and finally beam delivery to first users. Assessed beam properties included per-pulse intensity, beam position, shape, lateral dimensions, and spectral properties. During this period, the machine provided up to 0.1 nm wavelength at up to 1.5 mJ pulse energy, up to 300 FEL pulses per train, and up to 4.5 MHz intra-bunch train repetition. [ABSTRACT FROM AUTHOR]

The stable trajectory of a charged particle in an external guiding field is an essential condition for its acceleration or for forcing it to generate radiation. Examples of possible guiding devices include a solenoidal magnetic field or permanent periodic magnet in klystrons, a wiggler in free-electron lasers, the lattice of any accelerator, and finally the crystal lattice for the case of channeling radiation. We demonstrate that the trajectory of a point-charge in a radially polarized laser Bessel beam may be stable similarly to the case of a positron that bounces back and forth in the potential well generated by two adjacent atomic planes. While in the case of channeling radiation, the transverse motion is controlled by a harmonic oscillator equation, for a Bessel beam the transverse motion is controlled by the Mathieu equation. Some characteristics of the motion are presented. [ABSTRACT FROM AUTHOR]

Laser-plasma accelerators (LPAs) have the potential to drive compact free-electron lasers (FELs). Even with LPA energy spreads typically at the percent level, the e-beam brightness can be excellent, due to the low normalized emittance (<0.5 µm) and high peak current (multi-kA) resulting from the ultra-short e-beam duration (few fs). It is critical, however, that in order to mitigate the effect of percent-level energy spread, one has to actively manipulate the phase-space distribution of the e-beam. We provide an overview of the methods proposed by the various LPA FEL research groups. At the BELLA Center at LBNL, we are pursuing the use of a chicane for longitudinal e-beam decompression (therefore greatly reducing the slice energy spread), in combination with short-scale-length e-beam transportation with an active plasma lens and a strong-focusing 4-m-long undulator. We present ELEGANT & GENESIS simulations on the transport and FEL gain, showing strong enhancement in output power over the incoherent background, and present estimates of the 3D gain length for deviations from the expected e-beam properties (varying e-beam lengths and emittances). To highlight the role of collective effects, we also present ELEGANT & GENESIS simulation results. [ABSTRACT FROM AUTHOR]

The development of the fourth generation light sources based on the X-ray free electron laser (XFEL) opens new perspectives in the investigation of high-energy-density plasmas. The properties of these tunable X-ray laser sources permit to consider an active spectroscopy experiments to improve the understanding of hot and dense plasmas. In this work, we present prospective calculations of spectral line shapes and redistribution functions of the neon-like aluminum 1s2s22p6nl - 1s22s22p5nl, (n = 3, 4, 5, ..) and 1s2s22p63l - 1s22s22p6 lines at 1490 eV and 1572 eV, respectively, for typical laser-plasma conditions. These calculations are based on a theoretical model for calculating the redistribution function in hot and dense plasmas. It relies on an extension of the Frequency Fluctuation of Model. This model takes into account the complexity of the atomic structure of ionic emitters and the various line broadening mechanisms including effects of the emitter environment fluctuations. [ABSTRACT FROM AUTHOR]