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Superconducting Undulators (SCUs) can produce higher photon flux and cover a wider photon energy range compared to permanent magnet undulators (PMUs) with the same vacuum gap and period length.To build the know-how to implement superconducting undulators for future upgrades of the European XFEL facility, the test stand SUNDAE1 for the characterization of SCU is being developed. The purpose of SUNDAE1 is the training, tuning and development of new SCU coils by means of precise magnetic field measurements.The experimental setup will allow the characterization of magnets up to 2m in length. These magnets will be immersed in a Helium bath at 4K or 2K temperature.In this article, we describe the experimental setup and highlight its expected performances.

Journal of physics / Conference Series 2380(1), 012043 (2022). doi:10.1088/1742-6596/2380/1/012043, The successful implementation of the baseline instruments at the European XFEL has triggered a second phase of instrument developments aiming to extend the portfolio of available techniques. At the soft X-ray undulator (SASE 3), the Soft X-ray Port (SXP) instrument is currently under construction. Conceived as an open port, it focuses primarily on femtosecond time-resolved X-ray photoelectron spectroscopy (TR-XPES), which has proven to be a powerful tool to understand the properties of materials and the interaction between their internal degrees of freedom. The extension of this technique to the soft X-ray energy range is only possible at MHz free electron lasers (FELs) due to space-charge effects which limit the maximum photon flux per pulse on the sample. In this contribution, the SXP instrument at the European XFEL and the implementation of TR-XPES using a momentum microscope are presented. The photon energy range available at SASE 3, 0.25 keV to 3.5 keV, and the variable polarization will allow for the simultaneous characterization of the electronic, magnetic, chemical and structural properties of materials with femtosecond time resolution. To this end, a wide range of laser excitation wavelengths, ranging from the XUV to the THz region, will be available., Published by IOP Publ., Bristol

The recent start of the European X-ray Free-Electron Laser (EuXFEL) provides a unique pulsed X-ray source of high spectral brilliance and high photon flux at a high repetition rate and opens the possibility for new scientific opportunities. However, the EuXFEL beam has a high peak power that is converted into a high cyclic thermal load on the optical elements, such as mirrors and monochromators, and is impossible to fully mitigate within the pulse train pattern. In the single crystal based X-ray monochromators, the increase of temperature leads to deformation of the crystal structure which affects the rocking curve and consequently the performance of these devices and the quality of the transmitted X-ray beam. To address the increase of temperature, we propose the use of a diamond channel-cut monochromator as an alternative to the current silicon monochromators. In this work we present the design and parameters of the diamond monochromator, heat load simulations and the surface and crystalline quality characterisation. The heat load simulations indicate a high performance of the monochromator under the pulse train of the EuXFEL and the characterisation demonstrates high crystal quality and its functionality as a double crystal monochromator.

In the X-ray FEL beam transport system, the optic components which have direct contact with the beam, e.g. mirror, absorber and beam shutter, etc., could exceed 10 kW peak heat load on a sub-mm spot. Therefore, the thermo-mechanical performance of these components under the extreme high heat load will limit the maximum allowed pulses for the safety operation of the facility. In this contribution, a selection of multi-scale and multi-physics numerical models using finite element tools is introduced to describe the interaction of X-ray laser beam with different materials, taking into consideration of the multi-coupling of heat transfer, solid mechanics, fluid dynamics and phase transitions. The verified and validated models can be referred to define damage threshold of the optic components, and to virtually reproduce the damage mechanism of the materials.

Recently, a scientific comparison of flatness measuring instruments at European National Metrology Institutes (NMIs) was performed in the framework of EURAMET. The specimen was a well-polished optical surface with a maximum measurement aperture of 150 mm in diameter. Here, we present an evaluation concept, which allows the determination of a mean flatness map taking into account different lateral resolutions of the instruments and different orientations of the specimen during measurement. We found that all measurements are in agreement with the mean flatness map within the uncertainty intervals stated by the participants. The aim of this scientific comparison is to specify an appropriate operation and evaluation procedure for future comparisons.

Nature photonics 14(6), 391 - 397 (2020). doi:10.1038/s41566-020-0607-z, 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., Published by Nature Publ. Group, London [u.a.]

An accurate control of the optical properties of single crystal diamond during microfabrication processes such as ion implantation plays a crucial role in the engineering of integrated photonic devices. In this work we present a systematic study of the variation of both real and imaginary parts of the refractive index of single crystal diamond, when damaged with 2 and 3 MeV protons at low-medium fluences (range: 10^15 - 10^17 cm^-2). After implanting in 125x125 um^2 areas with a scanning ion microbeam, the variation of optical pathlength of the implanted regions was measured with laser interferometric microscopy, while their optical transmission was studied using a spectrometric set-up with micrometric spatial resolution. On the basis of a model taking into account the strongly non-uniform damage profile in the bulk sample, the variation of the complex refractive index as a function of damage density was evaluated., 13 pages, 7 figures. arXiv admin note: text overlap with arXiv:1608.07122

A new method of preparation of silicon-on-diamond materials is discussed in detail. Pre-characterization of the samples surfaces has been carried out, in order to calculate the optimal pressure for surface contact before the bonding process. The method is based on pulsed laser irradiation, in the 20 ps–7 ns range, at a wavelength of 355 nm, for which diamond is transparent and silicon highly absorbing. Under these conditions the material melts locally, within 100 nm at the interface, giving rise to amorphous silicon and silicon carbide. The mechanical strength of the bonding has been assessed by adhesion tests. Preliminary result on resistance to thermal annealing at 400 C in air is also reported. Uniformity of the silicon–diamond interface has been verified by scanning electron microscopy. Raman and infrared spectroscopy allowed to detect and estimate quantitatively the amorphous Si and SiC phases at the interface. A finite element simulation has been carried out, taking into account the processes occurring during the laser pulse and the subsequent cooling of the materials. As a result, energy densities per pulse required to melt locally diamond and silicon have been obtained as functions of the pulse width, giving a rationale to the formation of the SiC bond in terms of diamond–silicon inter diffusion. The experimental results of bondings performed at various energy density and pulse widths are in agreement with the model. The experimental results and the theoretical predictions are compared and discussed.

Research experiments and advanced applications often require the knowledge of the refractive index of vitreous materials under specific environmental conditions. Measurements are carried out by placing the glass sample in a cell where the required conditions are established; the probe beam enters and exits the cell through a pair of windows. A typical case is the measurement in vacuum, as it occurs when thermal cycles down to cryogenic temperatures have to be performed. In such a case, data processing has to take into account the specific geometry of the cell and the windows. Here we present closed formulas for a symmetrical configuration, and a ray tracing approach for general cases where symmetry is not guaranteed. In particular, the experimental configuration is conveniently modeled, and ray tracing is used to find out the conditions of minimum deviation, starting from a tentative value of the refractive index. The latter is successively modified until the data actually obtained from experiments are matched. Specific software is developed, accomplishing the computation task automatically by recursive iterations. The ray-tracing model is also used to numerically estimate the sensitivity of the results to the influence variables, and to work out the uncertainty balance.

A new optical configuration producing one-step 360 degrees rainbow holograms is presented. The method makes use of two concave mirrors in confocal position, with an annular aperture between the two. An experimental demonstration is given.

Fused silica plates are used in most metrology laboratories as planarity standard. Usually, these standards are calibrated in upright position, to minimize bending effects due to gravity. On the other hand, for particular applications or very large flats, it would be useful to know the absolute surface error when they are supported in horizontal position, i.e., with their axis vertical. Here we report a study regarding this setup for planarity calibration, comparing two different experimental methods with respect to predictions of finite elements analysis.

Photonic crystals are attractive optical materials for controlling and manipulating light. They are of great interest for both fundamental and applied research, and are expected to find commercial applications soon. In this work digital holography, white light interferometry and atomic force microscopy have been applied to the inspection and characterization of 1D and 2D nanofabricated LiN photonic crystals. Periodic pattern with periods ranging form several microns to a fraction of micron have been accurately analysed. Optical methods allow exploring relatively large areas while atomic force microscopy is well suited for high-resolution inspection of the small features.

A simplified version of the liquid mirror setup to serve as planarity reference standard is described in detail. Particulars of the mounting, maintenance and use of the mirror are provided. A series of measurements over a diameter of 90 mm is reported; the resulting expanded uncertainty for the peak-to-valley achieved in experiments is 7 nm (2 sigma).

This paper presents a new tele-operated robotic chain for real-time ultrasound image acquisition and medical diagnosis. This system has been developed in the frame of the Mobile Tele-Echography Using an Ultralight Robot European Project. A light-weight six degrees-of-freedom serial robot, with a remote center of motion, has been specially designed for this application. It holds and moves a real probe on a distant patient according to the expert gesture and permits an image acquisition using a standard ultrasound device. The combination of mechanical structure choice for the robot and dedicated control law, particularly nearby the singular configuration allows a good path following and a robotized gesture accuracy. The choice of compression techniques for image transmission enables a compromise between flow and quality. These combined approaches, for robotics and image processing, enable the medical specialist to better control the remote ultrasound probe holder system and to receive stable and good quality ultrasound images to make a diagnosis via any type of communication link from terrestrial to satellite. Clinical tests have been performed since April 2003. They used both satellite or Integrated Services Digital Network lines with a theoretical bandwidth of 384 Kb/s. They showed the tele-echography system helped to identify 66% of lesions and 83% of symptomatic pathologies.

We discuss classical experiments in the field of laser speckle interferometry. The typical optical setup consists of a laser diode and off-the-shelf optical elements, like a lens to expand the beam and plane mirrors to deflect it. A low-cost commercial CCD photocamera is used to acquire the speckle images. Items investigated are diffusing objects, illuminated with the laser diode and imaged on the CCD under appropriate experimental conditions. Pictures are taken both with the object at rest and under stress. The pictures are subtracted from one another with a standard software, pixel by pixel; the subtraction reveals fringes of the deformation occurred between the two exposures. With interferograms obtained in this way, we can study mechanical systems with an accuracy of the order of the wavelength of the light source used. Changing the optical setup, the measurement becomes sensitive to stresses along the camera optical axis direction (out-of-plane) or in the perpendicular plane (in-plane). Making long-time exposures it is also possible to study vibrational modes of suitable items (time-average). Three different setups are investigated and examples of measurement are reported.

Confidence building measures (CBMs), particularly military ones, that address the security needs of North and South Korea could decrease the risk of conflict on the Korean Peninsula and help create an environment in which to negotiate a peace regime. The Korea Institute for Defense Analyses (KIDA) and the Cooperative Monitoring Center (CMC) of Sandia National Laboratories collaborated to identify potential CBMs and define associated monitoring. The project is a conceptual analysis of political and technical options for confidence building that might be feasible in Korea at some future time. KIDA first analyzed current security conditions and options for CBMs. Their conclusions are presented as a hypothetical agreement to strengthen the Armistice Agreement by establishing Limited Force Deployment Zones along the Military Demarcation Line. The goal of the hypothetical agreement is to increase mutual security and build confidence. The CMC then used KIDA`s scenario to develop a strategy for cooperative monitoring the agreement. Cooperative monitoring is the collecting, analyzing and sharing of agreed information among parties to an agreement and typically relies on the use of commercially available technology. A cooperative monitoring regime must be consistent with the agreement`s terms; the geographic, logistic, military, and political factors in the Korean setting; and the capabilities of monitoring technologies. This report describes the security situation on the Korean peninsula, relevant precedents from other regions, the hypothetical agreement for reducing military tensions, a monitoring strategy for the hypothetical Korean agreement, examples of implementation, and a description of applicable monitoring technologies and procedures.

We present the fabrication and characterization of opto-mechanical micro-resonators developed to detect radiation-pressure coupling between light and a macroscopic body. The major achievements of this work are the development of complex high aspect ratio shapes by using the deep-RIE Bosch process and the integration of a high-reflectivity dielectric mirror. The micro-resonators were used as an end-mirror of a Fabry-Perot cavity, attaining an optical finesse of about 6 × 104, and at cryogenic temperature (about 10 K) we measured a mechanical quality factor up to 2 × 106 at about 90 kHz. These features make our devices particularly suitable for experiments on quantum-opto-mechanics.

This paper argues that cooperative monitoring plays a critical role in the implementation of regional security agreements and confidence building measures. A framework for developing cooperative monitoring options is proposed and several possibilities for relating bilateral and regional monitoring systems to international monitoring systems are discussed. Three bilateral or regional agreements are analyzed briefly to illustrate different possibilities. These examples illustrate that the relationship of regional or bilateral arms control or security agreements to international agreements depends on a number of factors: the overlap of provisions between regional and international agreements; the degree of interest in a regional agreement among the international community; efficiency in implementing the agreement; and numerous political considerations. Given the importance of regional security to the international community, regions should be encouraged to develop their own infrastructure for implementing regional arms control and other security agreements. A regional infrastructure need not preclude participation in an international regime. On the contrary, establishing regional institutions for arms control and nonproliferation could result in more proactive participation of regional parties in developing solutions for regional and international problems, thereby strengthening existing and future international regimes. Possible first steps for strengthening regional infrastructures are identified and potential technical requirements are discussed.

Consider a market with the following characteristics: 1) privacy, that is, each agent knows only his own valuation (or cost) conditions; 2) exchange follows the rules of the oral double auction, that is, buyers freely announce bids or accept offers and sellers freely announce offers or accept bids; 3) aggregate market supply and demand per trading period is stationary for at least two to three periods; and 4) there are at least four buyers, and as many sellers. The literature reporting the results of a large number of experimental markets with these characteristics documents what appears to be a remarkably rapid convergence to a competitive equilibrium (CE).' However, any claim of double auction (DA) "convergence" to the CE can only have meaning in one of three senses: (i) The CE is attained immediately. (ii) After T periods of trading, some measure of the market's state, such as mean price, is nearer, relative to experimental sampling variability, to a CE than to some distinct alternative equilibrium such as a monopoly or Nash equilibrium. (iii) After T periods of trading, this measure is nearer to a CE in DA experimental markets than in markets organized under a different institution of contract, for example, a sealed-bid auction. Since everything from electrons and the stars to rats and people yield state measures subject to "error" or random variation, the deterministic criterion (i) can have no serious scientific standing. By such criteria any hypothesis can be rejected and there could be no science of physics, biology, or economics.2 With the exception of certain very simple markets such as single object auctions, or certain idealized markets such as the Cournot quantity adjuster model, economics has only two concepts of equilibrium-monopoly and competitive. The only formal model of DA trading that has been proposed (see David Easley and John Ledyard, p. 6) predicts stochastic convergence (in finite time, with probability one) to a CE. Hence, the only test alternative to the CE research hypothesis in DA markets is a monopoly (or monopsony) equilibrium. Experimentalists have not reported statistical tests of the CE *Professor, department of economics, University of Arizona; assistant professor, department of economics, Indiana University; instructor, department of economics, University of Arizona; and Sandia National Laboratories, Albuquerque, NM, respectively. We are indebted to the National Science Foundation for research support, and to Art Denzau and Mort Kamien for helpful comments. 'There is an early and recently growing body of experimental evidence for convergence to a competitive equilibrium under double auction rules: the earliest evidence (contained in experiments initiated in January 1956) is reported in Smith (1962, 1964, 1965, 1976). However, these early experiments used between twenty and fifty or so participant buyers and sellers because, in keeping with prevailing professional beliefs, it was thought that a CE was unlikely to be approached unless numbers were quite large. Using large numbers was not unreasonable since it is a good beginning procedure to give a theory whatever is believed to be its "best shot." More recent evidence using six buyers, six sellers, and two traders in "speculative" DA markets with cyclical demand is reported by R. M. Miller, Charles Plott, and Smith, and Williams (1979). For evidence from a comparison of oral and computerized DA experiments with four buyers and four sellers, see Williams (1980). For further evidence in the context of the study of price controls, see M. Isaac and Plott (1981b) and Smith and Williams (1981b); in the context of a conspiracy study see Isaac and Plott (1981a); in the context of comparisons between DA and posted offer pricing, see Jon Ketcham, Smith, and Williams; in the context of a study of four variations on DA rules, see Smith and Williams (1980). All of these more recent papers report double auction experiments using no more than four buyers and four sellers. 2As Frederick Mosteller once noted, if you wanted to reject the inverse square law of attraction, try tossing a sheet of paper out the window.