Design and modeling of 40 keV X-ray optics for Titan experiment

In 2004 we designed and fabricated a 40 keV W/SiC multilayer coated mirrors with 2.0 nm period thickness that were tested at RAL (UK) in winter 2004/2005. The mirrors reflected from 35 to 70 keV (different grazing incidence angles) and showed high reflectivity. However, there was not enough beamtime at RAL to obtain quantitative results. Similar experiment will now be performed in Titan facility (LLNL). In this report we design and model multilayers with even shorter period than the ones used in 2004/2005 experiments. Our goal is to fabricate 1 nm period W/SiC multilayers with high reflectivity. This will enable operation at higher angle of grazing incidence and simplified the mounting fixture

LCLS soft x-ray imager mirrors and their performance

Soft X-ray imager mirrors have been designed, calibrated and fabricated at Lawrence Livermore National Laboratory and characterized at the Advanced Light Source for their performance between 200 and 1300 eV. The mirrors are coated with a multilayer coating consisting of 70 bilayers of W/ SiC. The mirrors are to reflect at 22.5 deg from grazing angle at 1.50 nm wavelength and the width of the reflectivity peak should be at least 1.3%. Also, the mirrors should be non-reflective elsewhere. Our multilayer design was optimized to satisfy these requirements. The coating is very challenging since the individual layer thicknesses need to be less than 1 nm thick and reproducibility from layer to layer is crucial. To minimize the second harmonic peak we designed a multilayer with {Gamma} = 0.5 (W and SiC layer thicknesses are the same). This way we end up with a mirror that has only the 1st and 3rd harmonic peak as shown in Figure 1. To suppress reflectivity outside the first peak we used our novel approach, an antireflective coating. Modeling predicted substantial reduction in reflectivity, especially for lower energies as shown in Figure 1. The experimental results of the soft x-ray imager mirror as measured at the ALS are shown in Figure 2 (log and linear scale). The energy range over which we measured the reflectivity is limited by the beamline hardware. This plot is a compilation of about six scans over different energy ranges using different gratings, filters and order sorter positions. The measured reflectivity of the peak at 1.505 nm is 4.3% with the peak width of 0.028 nm or 1.8%, satisfying the specs on the peak width. The other important specification was overall low reflectivity (except for 1st harmonic). We demonstrated this with the antireflective coating that is applied on these mirrors. The application of the antireflective coating also reduces the reflectivity of the 1st harmonic peak from 8.23% to 4.30%, which is in agreement with our modeling results. As shown in Figure 3 the antireflective coating substantially suppresses reflectivity in the energy range between 200 and 800 eV

Simultaneous imaging of the near- and far-field intensity distributions of the Ni-like Sn X-ray laser

We report two-dimensional near-field imaging experiments of the 11.9-nm Sn X-ray laser that were performed with a set of novel Mo/Y multilayer mirrors having reflectivities of up to ∼40% at normal and at 45° incidence. Second-moment analysis of the X-ray laser emission was used to determine values of the X-ray beam propagation factor M2 for a range of irradiation parameters. The results reveal a reduction of M2 with increasing prepulse intensity. The spatial size of the output is a factor of ∼2 smaller than previously measured for the 14.7-nm Pd X-ray laser, while the distance of the X-ray emission with respect to the target surface remains roughly the sam

Validation of a computational model for a coupled liquid and gas flow in micro-nozzles

The work presents verification of a numerical model for micro-jet focusing, where a coupled liquid and gas flow occurs in a gas dynamic virtual nozzle (GDVN). Nozzles of this type are used in serial femtosecond crystallography experiments to deliver samples into X-ray beam. The following performance criteria are desirable: the jet to be longer than 100 µm to avoid nozzle shadowing, the diameter as small as possible to minimize the background signal, and the jet velocity as high as possible to avoid sample’s double X-ray exposure. Previous comprehensive numerical investigation has been extended to include numerical analysis of the tip jet velocities. These simulations were then compared with the experimental data. The coupled numerical model of a 3D printed GDVN considers a laminar two-phase, Newtonian, compressible flow, which is solved based on the finite volume method discretization and interface tracking with volume of fluid (VOF). The numerical solution is calculated with OpenFOAM based compressible interFoam solver, which uses algebraic formulation of VOF. In experimental setup for model validation a 3D printed GDVN was inserted in a vacuum chamber with two windows used for illumination and visualization. Once the jet was stabilized its velocity was estimated based on a distance a droplet traveled between two consecutive illumination pulses with a known time delay. The experimental and computational study was performed for a constant liquid flow rate of 14 l/min and the gas mass flow rate in the range from 5 mg/min to 25 mg/min. The coupled numerical model reasonably predicts the jet speed and shape as a function of the gas flow

Correlated analyses of D- and 15N-rich carbon grains from CR2 chondrite EET 92042

Extract from introduction: Insoluble organic matter (IOM) and matrix from primitive carbonaceous chondrites carry isotope enrichments (?D?20000', ?15N?3200�) that are comparable to those in interplanetary dust particles [1, this work]. Hence, primitive organics that formed in the protosolar cloud (PSC) – or maybe in the cold outer regions of the protoplanetary disk – survived accretion and planetary processing on the asteroids, the parent bodies of the chondrites

Growth of thick, crystalline material using dc-magnetron sputtering in Mag1 deposition chamber

We demonstrated dense, non-columnar growth of thick Mo films by moving the substrates in and out of the plasma thus allowing the surface reconstruction and by interrupting the growth with Si layers. The multilayers made this way have very smooth surface, about 1.3 nm rms high spatial frequency roughness, while also maintaining the periodicity of a reflective coating. These preliminary results hint that the surface reconstruction is an important physical process that controls the growth mechanisms. Further studies, combined with theoretical modeling, are essential to further our knowledge on how to predict and control desired microstructure for different materials

Cryptotomography: reconstructing 3D Fourier intensities from randomly oriented single-shot diffraction patterns

We reconstructed the 3D Fourier intensity distribution of mono-disperse prolate nano-particles using single-shot 2D coherent diffraction patterns collected at DESY's FLASH facility when a bright, coherent, ultrafast X-ray pulse intercepted individual particles of random, unmeasured orientations. This first experimental demonstration of cryptotomography extended the Expansion-Maximization-Compression (EMC) framework to accommodate unmeasured fluctuations in photon fluence and loss of data due to saturation or background scatter. This work is an important step towards realizing single-shot diffraction imaging of single biomolecules.Comment: 4 pages, 4 figure

Planning and designing an integrated management of coastal hypoxia in the Emila Romagna region water (Northern Adriatic Sea)

Abstract The design of an integrated monitoring network useful for the early-warning, the management and mitigation of both the environmental and socio-economic costs of hypoxia/anoxia events in the Northern Adriatic coastal zone, south of the mouth of the Po river, is described in the contribute. It has been developed within the EMMA research project (Environmental Management through Monitoring and Modelling of Anoxia; LIFE04ENV/IT/0479) (2004-2007). Over the past few decades, hypoxia events have recurrently affected the coastal zone of Emilia Romagna Region (Italy). Data collected by the C.Z. lying in the Province of Rimini, because of its economic importance, are presented. The area is subjected to intense anthropogenic pressure due to its high population (416 000 equivalent inhabitants) with tourist seasonal peaks of up to 973 110 equivalent inhabitants (in summer time), to industrial and agricultural activity, to maritime traffic and nutrient river discharges (about 600 tons y-1 of nitrogen and 300 tons y-1 of phosphorus, in 2002). Hypoxia and anoxia have a negative effect on the quality of bathing waters as well as on fishing and mussel farming, which are important activities for the economy of the area. The planning of the monitoring network has been carried out by analyzing the scientific knowledge on hypoxia in the local area; its integration with other existing monitoring activities, available facilities and data resources was considered in order to optimize cost effectiveness of the network

Optics and multilayer coatings for EUVL systems

EUV lithography (EUVL) employs illumination wavelengths around 13.5 nm, and in many aspects it is considered an extension of optical lithography, which is used for the high-volume manufacturing (HVM) of today's microprocessors. The EUV wavelength of illumination dictates the use of reflective optical elements (mirrors) as opposed to the refractive lenses used in conventional lithographic systems. Thus, EUVL tools are based on all-reflective concepts: they use multilayer (ML) coated optics for their illumination and projection systems, and they have a ML-coated reflective mask