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Integrated X-ray testing of the electro-optical breadboard model for the XMM reflection grating spectrometer

Description: X-ray calibration of the Electro-Optical Breadboard Model (EOBB) of the XXM Reflection Grating Spectrometer has been carried out at the Panter test facility in Germany. The EOBB prototype optics consisted of a four-shell grazing incidence mirror module followed by an array of eight reflection gratings. The dispersed x-rays were detected by an array of three CCDs. Line profile and efficiency measurements where made at several energies, orders, and geometric configurations for individual gratings and for the grating array as a whole. The x-ray measurements verified that the grating mounting method would meet the stringent tolerances necessary for the flight instrument. Post EOBB metrology of the individual gratings and their mountings confirmed the precision of the grating boxes fabrication. Examination of the individual grating surface`s at micron resolution revealed the cause of anomalously wide line profiles to be scattering due to the crazing of the replica`s surface.
Date: July 12, 1994
Creator: Bixler, J. V.; Craig, W.; Decker, T.; Aarts, H.; Boggende, T. den; Brinkman, A. C. et al.
Partner: UNT Libraries Government Documents Department

A Soft X-ray Spectrometer using a Highly Dispersive Multilayer Grating

Description: There is a need for higher resolution spectrometers as a tool for inelastic x-ray scattering. Currently, resolving power around R = 10,000 is advertised. Measured RIXS spectra are often limited by this instrumental resolution and higher resolution spectrometers using conventional gratings would be prohibitively large. We are engaged in a development program to build blazed multilayer grating structures for diffracting soft x-rays in high order. This leads to spectrometers with dispersion much higher than is possible using metal coated-gratings. The higher dispersion then provides higher resolution and the multilayer gratings are capable of operating away from grazing incidence as required. A spectrometer design is presented with a total length 3.8m and capable of 10{sup 5} resolving power.
Date: January 31, 2010
Creator: Warwick, Tony; Padmore, Howard; Voronov, Dmitriy & Yashchuk, Valeriy
Partner: UNT Libraries Government Documents Department

Time-Resolved Hard X-Ray Spectrometer

Description: Wired array studies are being conducted at the SNL Z accelerator to maximize the x-ray generation for inertial confinement fusion targets and high energy density physics experiments. An integral component of these studies is the characterization of the time-resolved spectral content of the x-rays. Due to potential spatial anisotropy in the emitted radiation, it is also critical to diagnose the time-evolved spectral content in a space-resolved manner. To accomplish these two measurement goals, we developed an x-ray spectrometer using a set of high-speed detectors (silicon PIN diodes) with a collimated field-of-view that converged on a 1-cm-diameter spot at the pinch axis. Spectral discrimination is achieved by placing high Z absorbers in front of these detectors. We built two spectrometers to permit simultaneous different angular views of the emitted radiation. Spectral data have been acquired from recent Z shots for the radial and polar views. UNSPEC1 has been adapted to analyze and unfold the measured data to reconstruct the x-ray spectrum. The unfold operator code, UFO2, is being adapted for a more comprehensive spectral unfolding treatment.
Date: March 1, 2007
Creator: Moya, Kenneth; McKenna, Ian; Keenan, Thomas & Cuneo, Michael
Partner: UNT Libraries Government Documents Department

Omega Dante Soft X-Ray Power Diagnostic Component Calibration at the National Synchrotron Light Source

Description: The Dante soft x-ray spectrometer installed on the Omega laser facility at the Laboratory for Laser Energetics, University of Rochester is a twelve-channel filter-edge defined x-ray power diagnostic. It is used to measure the absolute flux from direct drive, indirect drive (hohlraums) and other plasma sources. Calibration efforts using two beam lines, U3C (50eV-1keV) and X8A (1keV-6keV) at the National Synchrotron Light Source (NSLS) have been implemented to insure the accuracy of these measurements. We have calibrated vacuum x-ray diodes, mirrors and filters.
Date: April 15, 2004
Creator: Campbell, K; Weber, F; Dewald, E; Glenzer, S; Landen, O; Turner, R et al.
Partner: UNT Libraries Government Documents Department

High-resolution, high-transmission soft x-ray spectrometer for the study of biological samples

Description: We present a variable line-space grating spectrometer for soft s-rays that coverst the photon energy range between 130 and 650 eV. The optical design is based on the Hettrick-Underwood principle and tailored to synchrotron-based studies of radiation-sensitive biological samples. The spectrometer is able to record the entire spectral range in one shot, i.e., without any mechanical motion, at a resolving power of 1200 or better. Despite is slitless design, such a resolving power can be achieved for a source spot as large as (30 x 3000) micrometers squared, which is important for keeping beam damage effects in radiation-sensitive samples low. The high spectrometer efficiency allows recording of comprehensive two-dimensional resonant inelastic soft x-ray scatters (RIXS) maps with good statistics within several minutes. This is exemplarily demonstrated for a RIXS map of highly oriented pyrolytic graphite, which was taken with 10 min.
Date: June 11, 2009
Creator: Fuchs, Oliver; Weinhardt, L.; Blum, M.; Welgand, M.; Umbach, E.; Bar, M. et al.
Partner: UNT Libraries Government Documents Department

Development, fabrication, and metrology of the electro-optical breadboard model for the reflection grating array of the XMM grating spectrometer

Description: A prototype array consisting of eight diffraction gratings has been fabricated for the XMM Reflection Grating Spectrometer. A component of the full spectrometer is an array of approximately 200 diffraction gratings. The diffraction gratings were produced using lightweight silicon carbide substrates and a replication technique. The prototype array was developed and assembled using the same tolerances as the flight arrays which have typical tolerances of 3 {mu}m in translation and sub-arc seconds in rotation. The metrology applied during inspection and assembly included precision linear measurements, full aperture figure measurements, and angular interferometry.
Date: July 1, 1994
Creator: Decker, T. A.; Montesanti, R. C.; Bixler, J. V.; Hailey, C. J. & Kahn, S. M.
Partner: UNT Libraries Government Documents Department

Evaluation of field-portable X-ray fluorescence spectrometry for the determination of lead contamination on small-arms firing ranges

Description: Field analytical methods for the characterization of lead contamination in soil are being developed. In this study, the usefulness of a commercially available, field-portable energy-dispersive X-ray fluorescence spectrometer (XRF) is evaluated for determining the extent of lead contamination in soils on small-arms firing ranges at a military installation. This field screening technique provides significant time and cost savings for the study of sites with lead-contaminated soil. Data obtained with the XRF unit in the field are compared with data obtained from soil samples analyzed in an analytical laboratory by inductively coupled plasma atomic emission spectroscopy. Results indicate that the field-portable XRF unit evaluated in this study provides data that are useful in determining the extent and relative magnitude of lead contamination. For the commercial unit used in this study, improvements in the spectral resolution and in the limit of detection would be required to make the unit more than just a screening tool.
Date: February 1, 1995
Creator: Schneider, J.F.; Taylor, J.D.; Bass, D.A.; Zellmer, D. & Rieck, M.
Partner: UNT Libraries Government Documents Department

Industrial x-ray fluorescence analysis new applications and challenges for cryogenic detectors

Description: Cryogenic, high-resolution X-ray detectors have potential applications in industrial X-ray fluorescence (XRF) analysis. We discuss various XRF analysis techniques currently used in the semiconductor industry, problems encountered due to limitations of current detectors and the potential benefits of using cryogenic detectors in these applications. We give examples of demonstration experiments, compare the performance of current conventional and cryogenic X-ray spectrometers and present an outlook.
Date: August 1, 1997
Creator: Frank, M.
Partner: UNT Libraries Government Documents Department

High-resolution superconducting x-ray spectrometers with an active area of 282 um x 282 um

Description: Superconducting tunnel junctions coupled to superconducting absorbers may be used as high-resolution, high-efficiency X-ray spectrometers. We have tested devices with niobium X-ray absorbing layers coupled to aluminum layers that serve as quasiparticle traps. In this work we measured the current pulses from a large area tunnel junction using an amplifier based on an array of 100 SQUIDs. Using this amplifier and a 282 micron X 282 micron junction, we have measured an energy resolution of 19 eV FWHM for 1.5 keV X rays and 21 eV for 2.6 keV X rays. The area of this junction is eight times the area of any junction previously measured to have such high energy resolution.
Date: September 11, 1996
Creator: Mears, C.A.; Labov, S.E.; Frank, M.; Netel, H.; Hiller, L.J.; Lindeman, M.A. et al.
Partner: UNT Libraries Government Documents Department

Low-energy response of superconducting tunnel junction x-ray spectrometers

Description: Thin film structures incorporating metallic superconducting layers and tunnel junctions can be configured as low-energy X-ray spectrometers. We present results obtained when low-energy X-rays are absorbed in niobium films coupled to aluminum layers that serve as quasiparticle traps in an Nb/Al/Al{sub 2}O{sub 3}/Al/Nb tunnel junction X-ray detector. The linearity of the pulse height as a function of energy is discussed along with the energy dependence of the observed resolution and its relation to the broadening mechanisms. A resolution of 14 eV at 1 keV has been measured with our detector cooled to 0.3 K.
Date: December 31, 1994
Creator: Labov, S. E.; Hiller, L. H.; Measrs, C. A.; Frank, M.; Netel, H.; Azgui, F. et al.
Partner: UNT Libraries Government Documents Department

A 100 ps gated x-ray spectrometer

Description: Material opacities are of interest in many fields. We have developed a Bragg reflection spectrometer that is gated for imaging samples in a laser heated environment for opacity measurement. A micro-channel plate is coated with a photocathode material and a fast pulse is launched across it. Electrons are converted to photons in a phosphor and recorded on film. Optical gate pulse widths of 100 ps are achieved. Some optical pulse width and sensitivity enhancements are noted at launch and termination. Events of interest are 200 ps long. The framing window is approximately 250 ps in length. Timing jitter is a problem. The instrument timing networks have been examined, and the source of jitter is still unknown. Timing to 50 ps resolution is desired. Close in proximity to the laser-driven event leads to complications in shielding from hard x-rays, hot electrons and shock-driven damage. High Z materials provide shielding from hard x-rays. Magnets screen out hot electrons produced by laser-matter interactions Filters provide energy fiducials. PCD`s provide high resolution timing measurements. Data is recorded on film in a specially designed film pack. The instrument is designed to be used in the NOVA Laser Facility at Lawrence Livermore National Laboratory.
Date: September 1, 1995
Creator: Walsh, P.J.; Blake, R.L.; Caldwell, S.; Hockaday, M.; Chrien, R. & Smith, R.C.
Partner: UNT Libraries Government Documents Department

Science and Technology Review June 2002

Description: This Science and Technology Review has the following stories: (1) Fighting Bioterrorism, Fighting Cancer; (2) A Two-Pronged Attack on Bioterrorism--synthetic two-legged molecules will be excellent detectors of biowarfare agents and cancer cells; (3) Adaptive Optics Sharpen the View from Earth--astronomers are obtaining images with unprecedented resolution, thanks to telescopes equipped with adaptive optics developed at Livermore; (4) Experiments Re-create X Rays from Comets--Experiments using the Laboratory's electron beam ion trap and an x-ray spectrometer designed by the National Aeronautics and Space Administration are shedding light on how comets emit x rays as they pass the Sun; (5) Chemistry--50 Years of exploring the Material World--from isotopic analysis to atomic-level simulations of material behavior, Livermore's chemists and materials scientists apply their expertise to fulfill the Laboratory's mission.
Date: June 1, 2002
Creator: Budil, K.
Partner: UNT Libraries Government Documents Department

DEVELOPMENT OF A HIGH RATE HIGH RESOLUTION DETECTOR FOR EXAFS EXPERIMENTS.

Description: A new detector for EXAFS experiments is being developed. It is based on a multi-element Si sensor and dedicated readout ASICs. The sensor is composed of 384 pixels, each having 1 mm{sup 2} area, arranged in four quadrants of 12 x 8 elements, and wire-bonded to 32-channel front-end ASICs. Each channel implements low noise preamplification with self-adaptive continuous reset, high order shaper, band-gap referenced baseline stabilizer, one threshold comparator and two DAC adjustable window comparators, each followed by a 24-bit counter. Fabricated in 0.35{micro}m CMOS dissipates about 8mW per channel. First measurements show at room temperature a resolution of 14 rms electrons without the detector and of 40 rms electrons (340eV) with the detector connected and biased. Cooling at -35C a FWHM of 205eV (167eV from electronics) was measured at the Mn-K{alpha} line. A resolution of about 300eV was measured for rates approaching 100kcps/cm{sup 2} per channel, corresponding to an overall rate in excess of 10MHz/cm{sup 2}. A channel-to-channel threshold dispersion after DACs adjustment of 2.5 rms electrons was also measured.
Date: November 2002
Creator: De Geronimo, G.; O'Connor, P.; Beuttenmuller, R. H.; Li, Z.; Kuczewski, A. J. & Siddons, D. P.
Partner: UNT Libraries Government Documents Department

FRONT-END ASIC FOR HIGH RESOLUTION X-RAY SPECTROMETERS.

Description: We present an application specific integrated circuit (ASIC) for high-resolution x-ray spectrometers. The ASIC is designed to read out signals from a pixelated silicon drift detector (SDD). Each hexagonal pixel has an area of 15 mmz and an anode capacitance of less than 100 fF. There is no integrated Field Effect transistor (FET) in the pixel, rather, the readout is done by wirebonding the anodes to the inputs of the ASIC. The ASIC provides 14 channels of low-noise charge amplification, high-order shaping with baseline stabilization, and peak detection with analog memory. The readout is sparse and based on low voltage differential signaling. An interposer provides all the interconnections required to bias and operate the system. The channel dissipates 1.6 mW. The complete 14-pixel unit covers an area of 210 mm{sup 2}, dissipates 12 mW cm{sup -2}, and can be tiled to cover an arbitrarily large detection area. We measured a preliminary resolution of 172 eV at -35 C on the 6 keV peak of a {sup 55}Fe source.
Date: October 27, 2007
Creator: DE GERONIMO,G.; CHEN, W.; FRIED, J.; LI, Z.; PINELLI, D.A.; REHAK, P. et al.
Partner: UNT Libraries Government Documents Department

A broadband high-resolution elliptical crystal x-ray spectrometer for high energy density physics experiments

Description: Spectroscopic investigation of high temperature laser produced plasmas in general, and x-ray opacity experiments in particular, often requires instruments with both a broad coverage of x-ray energies and high spectral, spatial, and temporal resolution. We analyze the design, model the response, and report the commissioning of a spectrometer using elliptical crystals in conjunction with a large format, gated microchannel plate detector. Measurements taken with this instrument at the JANUS laser facilities demonstrate the designed spectral range of 0.24 to 5.8 keV, and spectral resolution E/{Delta}E > 500, resulting in 2 to 3 times more spectral data than achieved by previous spectrometer designs. The observed 100 picosecond temporal resolution and 35 {micro}m spatial resolution are consistent with the requirements of high energy density opacity experiments.
Date: March 31, 2006
Creator: Anderson, S G; Heeter, R F; Booth, R; Emig, J; Fulkerson, S; McCarville, T et al.
Partner: UNT Libraries Government Documents Department

Measurement of the relaxation time of hot electrons in laser-solid interaction at relativistic laser intensities

Description: The authors have measured the relaxation time of hot electrons in short pulse laser-solid interactions using a picosecond time-resolved x-ray spectrometer and a time-integrated electron spectrometer. Employing laser intensities of 10{sup 17}, 10{sup 18}, and 10{sup 19} W/cm{sup 2}, they find increased laser coupling to hot electrons as the laser intensity becomes relativistic and thermalization of hot electrons at timescales on the order of 10 ps at all laser intensities. They propose a simple model based on collisional coupling and plasma expansion to describe the rapid relaxation of hot electrons. The agreement between the resulting K{sub {alpha}} time-history from this model with the experiments is best at highest laser intensity and less satisfactory at the two lower laser intensities.
Date: August 22, 2006
Creator: Chen, H; Shepherd, R; Chung, H K; Dyer, G; Faenov, A; Fournier, K B et al.
Partner: UNT Libraries Government Documents Department

Quantifying the Sensitivity of Superconducting High-Resolution X-Ray Spectrometers

Description: Superconducting tunnel junction (STJ) X-ray spectrometers have been developed for synchrotron-based high-resolution soft X-ray spectroscopy. We are quantifying the improvements in sensitivity that STJ spectrometers can offer for the analysis of dilute specimens over conventional semiconductor and grating spectrometers. We present analytical equations to quantify the improvements in terms of spectrometer resolution, detection efficiency and count rate capabilities as a function of line separation and spectral background. We discuss the implications of this analysis for L-edge spectroscopy of first-row transition metals.
Date: October 4, 2004
Creator: Drury, O & Friedrich, S
Partner: UNT Libraries Government Documents Department

High-resolution spectroscopy using synchrotron radiation for surface structure determination and the study of correlated electron systems

Description: The surface structure of three molecular adsorbate systems on transition metal surfaces, ({radical}3 x {radical}3)R30{degrees} and (1.5 x 1.5)R18{degrees} CO adsorbed on Cu(111), and c(2x2) N2/Ni(100), have been determined using Angle-Resolved Photoemission Extended Fine Structure (ARPEFS). The adsorption site and bond lengths are reported for the adsorbate-metal bond and the first two substrate layers. The ARPEFS diffraction pattern of the shake-up peak for c(2x2) N2/Ni(100) is also discussed. A unique method of experimentally determining the angular momentum and intrinsic/extrinsic origin of core-level satellites is presented. We show for the first time that satellite peaks not associated with chemically differentiated atomic species display an ARPEFS intensity oscillation. Specifically, we present data for the C 1s from ({radical}3x{radical}3)R30 CO/Cu(111) and p2mg(2x1)CO/Ni(110), N is from c(2x2) N2/Ni(100), and Ni 3p from clean nickel(111). The satellite peaks in all cases exhibit ARPEFS curves which indicate an angular momentum identical to the main peak and are of an intrinsic nature. A Fourier Transform Soft X-ray spectrometer (FF-SX) has been designed and is under construction for the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. The spectrometer is designed for ultra-high resolution theoretical resolving power E/{Delta}E{approx}-10{sup 6} in the photon energy region of 60-120 eV. This instrument is expected to provide experimental results which sensitively test models of correlated electron processes in atomic and molecular physics. The design criteria and consequent technical challenges posed by the short wavelengths of x-rays and desired resolving power are discussed. The fundamental and practical aspects of soft x-ray interferometry are also explored.
Date: May 1, 1996
Creator: Moler, E.J. Jr.
Partner: UNT Libraries Government Documents Department

X-ray laser interferometry: A new tool for AGEX

Description: Collisionally pumped soft x-ray lasers now operate over a wavelength range extending from 4--40 nm. With the recent advances in the development of multilayer mirrors and beamsplitters in the soft x-ray regime, we can utilize the unique properties of x-ray lasers to study large, rapidly evolving laser-driven plasmas with high electron densities. By employing a shorter wavelength x-ray laser, as compared to using conventional optical laser as the probe source, we can access a much higher density regime while reducing refractive effects which limit the spatial resolution and data interpretation. Using a neon-like yttrium x-ray laser which operates at a wavelength of 15.5 mn, we have performed a series of soft x-ray laser interferometry experiments, operated in the skewed Mach-Zehnder configuration, to characterize plasmas relevant to both weapons and inertial confinement fusion. The two-dimensional density profiles obtained from the interferograms allow us to validate and benchmark our numerical models used to study the physics in the high-energy density regime, relevant to both weapons and inertial confinement fusion.
Date: October 1, 1995
Creator: Wan, A.S.; Moreno, J.C. & Libby, S.B.
Partner: UNT Libraries Government Documents Department

Preliminary optical design of a varied line-space spectrograph for the multi-channel detection of near-edge X-ray absorption fine structure (NEXAFS) spectra in the 280-550 eV energy range

Description: The optical design of a varied line-space spectrograph for the multi-channel recording of NEXAFS spectra in a single {open_quotes}snapshot{close_quotes} is proposed. The spectrograph is to be used with a bending magnet source on beamline 7.3.2 at the Advanced Light Source (ALS). Approximately 20 volts of spectra are simultaneously imaged across a small square of material sample at each respective K absorption edge of carbon, nitrogen, and oxygen. Photoelectrons emitted from the material sample will be collected by an electron imaging microscope, the view field of which determines the sampling size. The sample also forms the exit slit of the optical system. This dispersive method of NEXAFS data acquisition is three to four orders of magnitude faster than the conventional method of taking data point-to-point using scanning of the grating. The proposed design is presented along with the design method and supporting SHADOW raytrace analysis.
Date: July 1, 1996
Creator: Wheeler, B.S.; McKinney, W.R.; Hussain, Z. & Padmore, H.
Partner: UNT Libraries Government Documents Department

Properties of plasma radiation diagnostics

Description: A number of diagnostics utilizing the radiation emitted from high-temperature plasmas have been developed at Los Alamos. Photoemissive x-ray diodes with photon energy bandpass filters provide time resolved rough spectral data from bout 6 eV to > 10 keV photon energy. Filtered silicon photodiodes can be used down to 1 eV and offer the advantages of nominally flat response and ability to operate in poor vacuum conditions. Both types of diodes will provide a rough time resolved spectrum and both are relatively inexpensive, reliable, and passive (i.e. no synchronization problems). For higher energy resolution bent crystal spectrographs are used in the x-ray region. With the addition of streak cameras or gated microchannel plates these systems provide data with high energy and high time resolution. To measure the total energy output a thin foil bolometer is used that measures the change in foil resistance as it is heated by the plasma radiation. Information on the physical location of the plasma is provided by a suite of visible framing cameras and x-ray pinhole cameras. By combining these diagnostics into a complementary set good diagnostic information can be guaranteed on any plasma experiment.
Date: June 1, 1996
Creator: Idzorek, G.C. & Oona, H.
Partner: UNT Libraries Government Documents Department

Cryogenic high-heat-load optics at the advanced photon source

Description: Cryogenically cooled silicon monochromators have found wide application at the Advanced Photon Source (APS) and other third-generation synchrotron radiation facilities. Currently, 17 insertion device beamlines at the APS are implementing cryogenic, silicon double-crystal monochromators (DCM) at the first optical element. Recently, several silicon crystal monochromators internally cooled with liquid nitrogen have been tested on the sector 1-ID undulator beamline at the APS. Rocking curves at various energies were measured simultaneously in first and third order from a Si(111) DCM in the Bragg reflection geometry at a fixed undulator gap of 11.1 mm. The crystal exhibited a sub-arc second thermal broadening of the rocking curve over a first order energy range from 6.0 to 17.0 keV up to a maximum incident power of 561 W in a 2.5 V x 2.0 H mm{sup 2} beam. It has been demonstrated that cryogenic silicon monochromators can handle the highest power beams from hard x-ray undulators at the APS without significant thermo-mechanical distortion.
Date: June 1, 1997
Creator: Rogers, C.S.
Partner: UNT Libraries Government Documents Department