bluuebunny/crossref_metadata_2025 huggingface dataset:
Statistical method for efficient determination of electron temperature from pulse height analysis of soft x rays in Heliotron E
Authors: Kaneko H. , Tohda T. , Kondo K. , Zushi H. , Iiyoshi A.
Published: July 2002

A pulse-height-analysis (PHA) technique of soft x rays is applied to Heliotron E experiments. The primary interest of this measurement is the determination of the electron temperature. Since the number of photons measured in a PHA system is extremely restricted owing to a finite processing rate of the system, it is most important to use the full amount of information involved in the spectral data. The statistical estimator from the maximum-likelihood method is efficiently used for this purpose. The estimated temperature is in good coincidence with the temperature by the electron-cyclotron-emission measurement, which is calibrated by the laser Thomson scattering. A check of reliability of the estimated electron temperature is developed from a statistical test of goodness of fit. The identification of impurity lines buried in a thermal spectrum is also discussed in the spectra accumulated through several or several tens of plasma discharges. The line emissions from Si, Cl, Ca, and Ti are identified. A systematic error in the estimated temperature due to the impurity lines is evaluated. The contributions from Cl and Ti cannot be neglected in the temperature estimation from a spectrum accumulated through several currentless ECH plasmas in Heliotron E. A removal of those contributions to the temperature estimation is successfully demonstrated. The electron temperature with several percent uncertainty is obtained by PHA every 10 ms during a Heliotron E discharge.
Soft x-ray microscope at the undulator beamline of the Photon Factory
Authors: Kagoshima Yasushi , Aoki Sadao , Kakuchi Masami , Sekimoto Misao , Maezawa Hideki , Hyodo Kazuyuki , Ando Masami
Published: July 2002

A soft x-ray microscope using Fresnel zone plates as optical imaging elements was installed at the Photon Factory. It makes use of undulator radiation as a source of soft x rays ranging from 2.0 to 3.0 nm in wavelength. The optical system was designed to match to the undulator radiation. A performance test was made at 2.66 nm by various pitches of transmission gratings. Those magnified images were taken with a magnification of 230 and exposure times of about 10 s. The modulation transfer function was measured over the spatial frequency up to 3300 lp/mm. Further, magnified images of some biological specimens were obtained.
Focusing x-ray beamline for macromolecular crystallography at the Photon Factory
Authors: Satow Yoshinori , Mikuni Akira , Kamiya Nobuo , Ando Masami
Published: July 2002

A beamline (BL 6A) for x-ray crystallography mainly utilizing photographic methods was designed and constructed at the Photon Factory. A focusing mirror was installed at the beamline in order to obtain a beam with high photon flux while eliminating higher energy x rays in the beam. The mirror chamber located at 11.8 m from the source point is maintained in a high vacuum so as to keep the mirror surface clean. It accommodates a 1.3-m-long steel holder on which a mirror block is mounted. Two types of mirror blocks, plane and cylindrical ones of fused quartz, are prepared for alternative use. A radiation shielding hutch placed at around 15 m from the source is sufficiently large for installing a monochromator and various types of cameras. When the plane mirror was bent vertically, the size of the focused beam at 15.3 m was reduced to about 0.18 mm in the vertical direction. By the use of focused x rays, preliminary Laue diffraction experiments were carried out on protein crystals. Good quality diffraction patterns recorded on imaging plates were obtained by exposure of several milliseconds.
A cine K-edge subtraction angiographic system for animal studies
Authors: Ueda Ken , Umetani Keiji , Takeda Tohoru , Akisada Masayoshi , Nakajima Teiichi , Anno Izumi , Yamaguchi Chiri
Published: July 2002

A cine k-edge subtraction imaging system has been constructed for less invasive transvenous angiography research. It utilizes synchrotron radiation and consists of a monochromator, an x-ray television camera with a high-speed shutter, and a data-acquisition and control unit. A 50×60-mm2 monochromatic x ray of about 400 mR/s intensity is produced. The x-ray photon energy is changed by using an oscillating cam mechanism which changes the angle of the crystal with respect to the beam. 16 ms is required to change the photon energy across the k edge for a change up to 800 eV. K-edge subtraction angiography of rats is performed following intravenous injection of materials containing iodine. Dual-energy images are acquired using 17-ms exposures with the same interval. Repetition of this sequence gives a series of k-edge subtraction images. Arteries of 0.3–0.4 mm diam are clearly seen.
Undulator heat loading studies on x-ray monochromators cooled with liquid gallium
Authors: Bilderback Donald H. , Henderson Chuck , White Jeff , Smither Robert K. , Forster George A.
Published: July 2002

Heat loading tests were conducted with up to 360 W of undulator radiation incident on liquid-gallium-cooled silicon monochromators. Rocking curve measurements and temperature profiles (infrared camera) were obtained as a function of beam current. With large heat loads, the width of the rocking curves were observed to broaden and the gain in output flux per mA of beam current was significantly less at high beam currents than during low-current operation. The best performance was obtained using a slotted crystal with cooling channels located 0.76 mm below the surface. This crystal showed strong heating effects only above 40 mA and continued to produce an increase in output flux with beam current at the highest current tested of 76 mA.
Mirrorchambers at HASYLAB
Authors: Bittner L. , Hahn U. , Saile V.
Published: July 2002

The design principles and the technical details for standard mirror chambers operated at HASYLAB are described.
Beamline X-11A at the NSLS: A unique facility for x-ray absorption spectroscopy
Authors: Heald S. M. , Sayers D. E.
Published: July 2002

The design and operation of beamline X-11A at the NSLS is described. It employs a unique optical design using a two/four crystal monochromator and a SiC collimating mirror. In either the two- or four-crystal mode a sagittal focusing crystal allows collection of up to 5 mrad of horizontal divergence. Two techniques for rapid scanning of a sagitally focusing crystal will be described and compared. These are dynamically bending the crystal during the scan or translating a fixed radius bent crystal in a manner to maintain a fixed focus on the sample. The flexibility of this two/four crystal design allows the intensity and/or resolution of the beamline to be optimized for particular experiments.
Compact storage rings Siberia-AS and Siberia-SM synchrotron radiation sources for lithography
Authors: Anashin V. V. , Arbuzov V. S. , Blinov G. A. , Veshcherevich V. G. , Vobly P. D. , Gorniker E. I. , Zinevich N. I. , Zinin E. I. , Zubkov N. I. , Kiselev V. A. , Kollerov E. P. , Kulipanov G. N. , Matveev Yu. G. , Medvedko A. S. , Mezentsev N. A. , Morgunov L. G. , Perevedentsev E. A. , Petrov V. M. , Petrov S. P. , Repkov V. V. , Roenko V. A. , Skrinsky A. N. , Sukhanov S. V. , Tokarev Yu.I. , Trakhtenberg E. M.
Published: July 2002

The paper deals with two projects of compact superconducting storage rings for industrial production of integrated circuits (IC) using x-ray lithography within the 8- to 20-Å wavelengths range. The azimuthally symmetric superconducting storage ring Siberia-AS at an energy of 600 MeV is a superconducting analog of VEP-1, one of the earliest storage rings in the world intended for the purposes of high-energy physics. Unlike the conventional design, no iron yoke is used in the storage ring under consideration to form the magnetic field at the equilibrium orbit and to close the return magnetic flux—this is performed by some inner and outer superconducting windings. Such a scheme enables the size of the storage ring to be substantially reduced (a cylinder of 2 m in diameter and 2 m long), and as a result, its weight decreases, too (about 10 tons). The eight-magnet storage ring Siberia-SM is of four-order symmetry so that the periodicity element comprises two rectangular magnets and three lenses. Its basic component is a superconducting bending rectangular magnet at a 6-T magnetic field. Two variants of such magnets have been proposed: in the first, the iron yoke is utilized to form the magnetic field and to close the return flux, while the second is an ironless C-shaped magnet manufactured on the basis of original wedgelike coils.
Scanning tunneling microscope with reliable coarse positioners
Authors: Takata K. , Hosoki S. , Hosaka S. , Tajima T.
Published: July 2002

An inchworm system with a new type of clamping mechanism has been made for a coarse positioner in a scanning tunneling microscope. The clamping mechanism operates by means of springs and piezoelectric actuators. This system can move a probe tip transversely and longitudinally in the horizontal plane, and the sample vertically, in steps, with a range of 8 mm in each direction.
Production of slow positron bunches using a microtron accelerator
Authors: Mills A. P. , Shaw E. D. , Chichester R. J. , Zuckerman D. M.
Published: July 2002

The microtron accelerator at Bell Laboratories presently produces 16-μs-long, 40-mA pulses of 18.5-MeV electrons at a repetition rate of 30 Hz. Energetic positron-electron pairs are produced at a 4-mm-thick W beam dump. The positrons are moderated to a few electron volts energy by a 9-mm-diam W(110) single crystal and bunched by a parabolic potential accelerator to 14-ns full width at half maximum bursts containing (7±1)×104 positrons. The collection efficiency of the buncher is 63%. With the buncher turned off, the positron production efficiency is 4×10−8 positrons per electron.
CCD and vidicon x-ray detectors: Theory and practice (invited)
Authors: Gruner Sol M.
Published: July 2002

Because of their ability to handle the highest count rates expected at synchrotron sources, CCD and vidicon-based two-dimensional x-ray detectors are being configured into many beam lines. Although the CCD or vidicon sensing element determines the ultimate capabilities of these detectors, the practical usage of these detectors is also constrained by the specific configuration of the phosphor, intensifier, optical coupling, and readout modes which are used. Results are presented on the design of CCD and vidicon-based detectors for a variety of x-ray imaging problems. The versatility and limitations of a variety of detector configurations are discussed.
Silicon-on-insulator produced by helium implantation and thermal oxidation
Authors: Raineri V. , Campisano S. U.
Published: July 2002

A novel technique that produces a high quality low cost silicon-on-insulator is described. The method takes advantage of the formation of a buried porous layer in silicon implanted with light ions. Trenches are then formed in such a way that O2 can be transported into the cavities. Finally, an oxidation in dry O2 produces a buried oxide layer. Helium ions at energies of 40 or 300 keV and fluences up to 2×1017/cm2 were uniformly implanted into 5 in. silicon wafers. The oxidations were performed in a rapid thermal oxidation system by using dry O2 at a temperature of about 1000 °C and for times up to 5 min. Transmission electron microscopy on cross sectional samples revealed that high quality buried oxide layers were formed and defect free single crystal silicon remained at the surface.
A new design for a UHV compatible Czochralski crystal growth system
Authors: Brown S. A. , Howard B. K. , Brown S. V. , Julian S. R.
Published: July 2002

We describe the design of a new system for the Czochralski growth of single crystals of intermetallic materials under ultrahigh vacuum conditions. Particular attention has been paid to an arrangement for very uniform movement of the pulling mechanism. We report the growth of large high-quality single crystals of MnSi.
Theoretical reflectivities of bent crystal analyzers for fusion plasma diagnostics
Authors: Caciuffo R. , Ferrero C. , Francescangeli O. , Melone S.
Published: July 2002

The performances of curved crystal analyzers used in the plasma diagnostic spectrometers at several fusion laboratories are evaluated by means of a physical model based on the dynamical theory of x-ray diffraction. We present reflectivity curves and diffraction parameters calculated as a function of the crystal curvature for different wavelengths corresponding to the most relevant spectra of metal impurity ions present in high-energy laboratory plasma sources.
Diagnostic complex for investigations of laser fusion physical processes
Authors: Bolotin V. A. , Burdonsky I. N. , Gavrilov V. V. , Yu. Gol’tzov A. , Zhuzhukalo E. V. , Zavyaletz S. V. , Kondrashov V. N. , Kovalsky N. G. , Pergament M. I.
Published: July 2002

The key physical processes of the laser fusion are well known and include the laser beam absorption, the heat transfer from the absorption zone to the ablation surface, the shell ablation acceleration and fusion fuel compression, the initiation of an effective thermonuclear burn. The first and second issues are investigated in detail on the small and moderate size facilities and high level of understanding is achieved on both phenomena. On the other hand, to study the thermonuclear burn seriously the large scale experiments should be carried out on the facilities of the next generation. Thus the efficiency and stability of the shell acceleration are today the main objects of experimental investigations in the majority of the laser fusion research laboratories. This paper is devoted to the development of the diagnostic methods just for studies of these problems.
TFTR multichannel neutron collimator
Authors: Roquemore A. L. , Chouinard R. C. , Diesso M. , Palladino R. , Strachan J. D. , Tait G. D.
Published: July 2002

The TFTR multichannel neutron collimator provides time-resolved neutron emission profiles from ten vertical chords spaced in major radius across the vacuum vessel. An in situ calibration of the system has been made using a 120 mCi 252Cf source scanned inside the vacuum vessel. A mapping of the effective neutron acceptance aperture was performed and showed reasonable agreement with the optical predictions testifying to the effectiveness of the interstitial shielding material. Crosstalk between channels was evaluated and found to be negligible. Periodic renormalization of the system has shown a standard deviation among the sensitivities of only 2.0% over the first seven months of operation.
Edge density fluctuation diagnostic for DIII-D using lithium beams
Authors: Thomas D. M. , Hyatt A. W. , Thomas M. P.
Published: July 2002

In order to investigate fluctuations in the edge regions of tokamaks and their influence on particle and energy transport, we are developing an ñ diagnostic for the DIII-D system based on an injected neutral lithium beam. Analysis of the 670.8 nm light emitted along the beam trajectory due to collisional excitation should yield the behavior of the electron density and its associated fluctuations in the edge region of DIII-D in both L- and H-mode plasma configurations. The planned system, design considerations, and expected performance levels will be presented.
RFX x-ray pulse height analysis system
Authors: Carraro L. , Valisa M.
Published: July 2002

The x-ray pulse height analysis diagnostic designed and built for the RFX reversed field pinch experiment is presented. The system is designed so as to be sensitive over a wide range of RFX operational conditions (100 eV ≤Te ≤ 2 keV). An array of three liquid N2 cooled Si(Li) detectors looks at the plasma through an equatorial port of the torus and can be tilted ±20° off the plane in order to scan over the central half of the minor diameter on a shot-to-shot basis. A second windowless single detector views the plasma along a fixed chord through a second equatorial port and is sensitive to x-ray energies as low as 500 eV. Commercial electronics are mostly used. The throughput is limited only by the shaping amplifier and pulse pileup rejector. Software simulation of the x-ray flux, including the pulse pileup rejection procedure of the electronic chain, was used to dimension the diagnostic, i.e., number of detectors, size of the apertures, and filter combinations. Preliminary tests indicate 20 ms as a realistic target for the electron temperature time resolution, reducible to 5 ms when all of the four detectors are addressed to the same properly chosen x-ray energy region.
Time-resolved x-ray crystal spectrometer for multiterawatt Z-pinch spectroscopy
Authors: Nash T. , Deeney C. , LePell P. D. , Prasad R. , Krishnan M.
Published: July 2002

A stripline gated microchannel plate framing camera is used as a detector in a crystal spectrometer. Typical 10 ns time gates are fast enough to record the evolution of both heating and expansion of Z pinches. By introducing spatially imaging cross slits, an x-ray spectrum from a Z pinch has been simultaneously space and time resolved.
Improved high-voltage, high-frequency square-wave generator
Authors: Bernius Mark T. , Chutjian Ara
Published: July 2002

We describe an improved design and operation of a prototype high-voltage full-floating, high-frequency square-wave generator over that first described in this journal [Rev. Sci. Instrum. 60, 779 (1989)]. The final design is seen to be more versatile, overcomes possible momentary simultaneous ON states in the totem-pole MOSFET configuration, and is less susceptible to deleterious effects caused by component aging, and replacements with nonidentical parts.
MTX diagnostic and timing system for free-electron laser heating experiments
Authors: Casper T. , Allen S. , Foote J. , Fenstermacher M. , Hooper E. , Hoshino K. , Lasnier C. , Makowski M. , Meyer W. , Moller J. , Nilson D. , Oasa K. , Ogawa T. , Rice B. , Sewall N. , Stallard B. , Stever R. , Thomassen K. , Wood R.
Published: July 2002

In the microwave tokamak experiment (MTX) program, we are concentrating on experiments using intense, free-electron laser (FEL) generated microwave pulses. In initial FEL experiments, several diagnostic instruments were operated during injection of microwave pulses with peak powers to 0.2 GW at durations of 10 ns. Fixed and spatially scanning microwave detectors and receivers and a 48-element calorimeter on the inside wall of MTX diagnosed the GW-level FEL microwave pulses. With these diagnostics, linear-wave absorption and efficiencies of transmission through the quasi-optical transport system were studied. In addition, several radially resolved measurements of plasma density, temperature, and emission were made during FEL injection and were used in the analysis of microwave absorption data. A timing system, slaved to the FEL pulse arrival time, is capable of accuracy to a few nanoseconds in order to allow measurement of heating effects on the time scale of a single FEL pulse.
An ac calorimeter for measuring heat capacity of free-standing liquid-crystal films
Authors: Geer R. , Stoebe T. , Pitchford T. , Huang C. C.
Published: July 2002

A unique ac calorimeter for measuring the heat capacity of free-standing liquid-crystal films has been developed. A theory of the measurement method used is presented and the experimental setup is discussed. The calorimeter has been used to study the nature of the smectic-A-hexatic-B transition of several liquid-crystal compounds. The evolution of the heat-capacity anomaly associated with this transition has been studied for films ranging from three to a few thousand smectic layers in thickness.
Analysis of multimode microwaves in oversize waveguide using an infrared camera image of radiated power distribution
Authors: Kiwamoto Y. , Kira F. , Saito T. , Miyoshi S. , Wada O. , Nakajima M.
Published: July 2002

A new method of mode analysis of multimode microwaves in an oversize waveguide is developed which utilizes infrared camera images of the radiation profile of microwaves launched from the waveguide end. Systematic variations of the radiation pattern with different phase shifts among constituent modes are compared with theoretical predictions to identify the constituent modes and to determine their fraction of power. Characteristics of a step-wise modulated TE02–TE01 mode converter are examined by using this method. It is demonstrated that this method is useful as a practical means for on-site analysis of waveguide properties.
Radio frequency signal processing with a monolithic four-quadrant multiplier
Authors: Kasal Miroslav , Hruby Ivan , Mustarelli Piercarlo , Scotti Sergio
Published: July 2002

A new monolithic and linear four-quadrant multiplier allows replacement of traditional hybrid-based circuits used in frequency conversion, and in-phase or amplitude modulation schemes. We demonstrate the advantages of this approach by evaluating the performances of a wideband amplitude and phase modulation unit built around the 500 MHz multiplier AD834. Key specifications of the unit we assembled are an 80 dB attenuation range, a 100 ns response time, a 360° range of phase shift, and an accuracy up to 0.02°. The device suits the phase and amplitude modulation needs of a nuclear magnetic resonance spectrometer.
Improving the performance of commercially available Geiger-mode avalanche photodiodes
Authors: Ghioni M. , Ripamonti G.
Published: July 2002

The resolution of Geiger-mode avalanche photodiodes in single photon timing is shown to be dependent on the diameter of the illuminated area. For the RCA C30902S device at room temperature, an improvement in the resolution from 460 to 320 ps FWHM (full width at half maximum) is demonstrated by concentrating the light in a 50-μm-diam spot in the center of the active area. The physical reasons that can justify such a result are dealt with. The resolution curve is affected by a tail due to diffusion effects. The tail shape and amplitude are investigated for different positions of the light spot on the active area and shown to be strongly position dependent. An analysis of the device structure accounts for this effect.
Efficient switchless multi-Joule TE-CO2 laser
Authors: Bhadani P. K. , Sylvan A. , Harrison R. G.
Published: July 2002

Switchless mode operation of a pulse TE-CO2 laser is reported. The system has provided an output energy of 7 J at atmospheric pressure from a discharge volume of 3 cm×3.3 cm×42 cm with an efficiency of 8%. Under long pulse loading, it has provided 3.5 J in a 5 μs pulse at an efficiency of 7% at a pressure of 500 mbar. The elimination of the high voltage switch from the main discharge circuit has resulted in a simple and inexpensive laser system.
Measurement under pressure of thermoelectric power along the thickness of a thin specimen
Authors: Ramasesha Sheela K. , Singh Anil K.
Published: July 2002

A method of measuring under pressure the thermoelectric power along the thickness of thin specimens is described. This method is useful in measuring thermoelectric power in a direction perpendicular to the cleavage plane of a crystal.
Rangefinder with fast multiple range capability
Authors: Payne J. M. , Parker D. , Bradley R.
Published: July 2002

A rangefinder is described that uses the propagation time of a beam of infrared radiation to measure distances of up to 120 m with errors of less than 50 μm. The instrument is capable of measuring up to five different distances per second by directing an amplitude modulated infrared beam to a retroreflector located at the far end of each path. The instrument is being tested with the expectation that such a system could be used to make precise and rapid measurements on a large radio telescope. Such measurements would be used to adjust the shape of the telescope reflector surface to correct for thermal and gravitational deformations taking place during astronomical observations. It is possible that the measuring system could be extended to relate the positions of certain moving parts of the structure to a reference system fixed in the ground, thus opening the possibility of making corrections to the telescope pointing.
Optical design and performance of the X25 hybrid wiggler beam line at the National Synchrotron Light Source
Authors: Berman Lonny E. , Hastings J. B. , Oversluizen Tom , Woodle Martin
Published: July 2002

The X25 beam line at the National Synchrotron Light Source (NSLS) began full-power commissioning in 1990. It extracts radiation from a 27 pole hybrid wiggler, which produces up to 1.8 kW of total power with a peak horizontal density of 450 W/mrad and critical energy of 4.6 keV. The design and performance of the beam line optics are described, in particular, the cooling of the first monochromator crystal.
Performance of very thin silicon single-crystal foils under high x-ray power density
Authors: Freund A. K. , Marot G. , Kawata H. , Joksch St. , Ziegler E. , Berman L. E. , Hastings J. B.
Published: July 2002

In this paper x-ray diffraction tests of very thin silicon single crystals exposed to a wiggler beam that can generate a power density up to 200 W/mm2 are reported on. This beam was provided by the beamline X25 at NSLS, where 75 W total power are focused into a spot of 0.8 mm(h)×0.45 mm(v). An 11 μm ‘‘thin’’ Si foil glued at its periphery onto an aluminum ring at 30 °C was applied to a box that could be pressurized with He. The whole assembly was then mounted on an optically polished and watercooled Be support. By increasing the temperature of the water and thus of the Al ring above 30 °C it was possible to apply a stretching force to the Si membrane in order to keep it flat. Rocking curves 3.3 arcsec wide were obtained with a strongly attenuated beam. The rocking curve width increased to 3.9 arcsec when the power density was increased to 15 W/mm2. The crystal was destroyed at 125 W/mm2 because of the limited thermal conductivity across the small He gap.
A novel monochromator for high heat load synchrotron x-ray radiation
Authors: Khounsary Ali M.
Published: July 2002

The high heat load associated with the powerful and concentrated x-ray beams generated by insertion devices (IDs) at a number of present and many of the future (planned or under construction) synchrotron radiation facilities poses a formidable engineering challenge for the design of monochromators and other optical devices. Successful utilization of the intense x-ray beams from insertion devices depends critically on the development, design, and availability of optical elements that provide acceptable performance under high heat load. Present monochromators can handle, at best, heat load levels that are an order of magnitude lower than those generated by these IDs. The monochromator described here, and referred to as the ‘‘inclined’’ monochromator, can provide a solution to the high heat load problem. The inclined monochromator is different in a number of aspects from other conventional monochromator designs. Its primary differentiating characteristic is in the orientation of the diffracting planes. In this geometry, the crystal surface normal and the normal to the diffracting crystal planes make an angle close to 90°. This leads to a number of interesting effects including spreading of the beam over a very large area (effectively reducing the incident heat flux), and also rendering a much smaller effective slope error. Thus, a substantial enhancement in the performance of the monochromator is realized. The preliminary results of a comparative numerical simulation of the performance of the inclined monochromator under the 5-kW power undulator A beam at the Advanced Photon Source are encouraging and provide a quantitative estimate of the expected enhancement.
Summary of the satellite workshop on thermal problems of synchrotron radiation optics
Authors: Freund Andreas K. , Mills Dennis M.
Published: July 2002

Highlights of a workshop on thermal problems of synchrotron radiation optics, a satellite meeting of the 4th International Conference on Synchrotron Radiation Instrumentation, will be presented. The most recent theoretical concepts and experimental results in studies of the thermal distortion of components exposed to the high heat loads of synchrotron radiation were discussed. Presentations were made on a variety of cooling techniques such as adaptive optical components, cryogenic cooling, nonstandard geometries (e.g., thin crystals and inclined crystals), and specialized materials (e.g., beryllium single crystals and multilayers), all of which attempt to mitigate the thermal effects on the performance of the x-ray optical components.
Multilayer gratings for the soft x-ray region (invited)
Authors: André J.-M. , Sammar A. , Kahn Malek C. , Troussel P. , Bac S. , Barchewitz R. , Pardo B. , Berrouane H. , Moreno T. , Ladan F. R. , Rivoira R. , Schirmann D.
Published: July 2002

New x-ray optics based on multidimensional diffraction are now available and have specific properties and potentials. Some characteristics of multilayer laminar amplitude gratings are presented in this work and exemplified with Mo/C multilayer etched gratings (1000 lines/mm) and (4166 lines/mm) for use in the 250 eV region and the 1 keV, respectively. The fabrication, tests of the gratings, and modeling of their diffractive performances are reported. Possible applications are discussed.
Absolute measurement of the spectral and angular properties of undulator radiation with a pinhole transmission grating spectrometer
Authors: Molter Karl , Ulm Gerhard
Published: July 2002

Absolute measurements of undulator radiation in the soft x-ray region from 50 to 500 eV are presented. A dedicated compact pinhole transmission grating spectrometer has been built, which was calibrated with relative uncertainties between 5% (at 100 eV) and 20% (at 500 eV) in the calculable undispersed dipole radiation of the storage ring BESSY. We report measurements of the spectral and angular radiation properties of the 35 period wiggler/undulator installed at BESSY for K parameters of 0.1 and 1.0. Good agreement with theoretical calculations is found.
Soft x-ray monochromator configurations for the ELETTRA undulators: A stigmatic SX700 (invited)
Authors: Jark Werner
Published: July 2002

This report presents a modification of an SX700 plane grating monochromator, which can be made to work stigmatically by introducing an entrance slit. It will then provide the highest possible photon density in the exit slit with resolving powers that can be very high because it is not any longer source-size limited. Instead it can be adjusted according to the slit settings. The deterioration of the resolving power because of slope errors in the ellipsoid can be avoided by orienting this mirror for sagittal focusing in the grating dispersion plane. In this configuration the instrument can be matched almost ideally to undulator sources.
Six-degree-of-freedom vibration isolation systems with application to resonant-mass gravitational radiation detectors
Authors: Aldcroft T. L. , Michelson P. F. , Taber R. C. , McLoughlin F. A.
Published: July 2002

In this paper we discuss passive vibration isolation systems for ultralow temperature gravitational radiation detectors, using a detector at Stanford University as the primary example. We review the basic theory of such isolation systems and describe methods of analysis for one-degree-of-freedom isolators. With these methods we derive fundamental constraints on the performance of gravitationally loaded isolators. Next we discuss general design considerations, optimization, and detailed analysis of six-degree-of-freedom isolators. We conclude with experimental data from isolators designed for the Stanford gravitational radiation detector.
High-resolution photoacoustic Ti:sapphire/dye ring laser spectrometer
Authors: Zhan Xiaowei , Kauppi Esa , Halonen Lauri
Published: July 2002

A high-resolution photoacoustic Ti:sapphire/dye ring laser spectrometer with a high level of automation is described. It produces high quality Doppler-limited overtone spectra. The performance of the spectrometer has been demonstrated by measuring both low- and high-resolution spectra of acetylene in the wave number regions 10850–12900 cm−1 and 11500–11650 cm−1, respectively. The spectra show large signal-to-noise ratios (≳7000) for strong absorption peaks. Some strong absorption lines have been compared with published FTIR spectral data.
Ion movie camera for particle-beam-fusion experiments
Authors: Stygar W. A. , Mix L. P. , Leeper R. J. , Maenchen J. , Wenger D. F. , Mattson C. R. , Muron D. J.
Published: July 2002

A camera with a 3 ns time resolution and a continuous (≳100 ns) record length has been developed to image a 1012–1013 W/cm2 ion beam for inertial-confinement-fusion experiments. A thin gold Rutherford-scattering foil placed in the path of the beam scatters ions into the camera. The foil is in a near-optimized scattering geometry and reduces the beam intensity∼seven orders of magnitude. The scattered ions are pinhole imaged onto a 2D array of 39 p-i-n diode detectors; outputs are recorded on LeCroy 6880 transient-waveform digitizers. The waveforms are analyzed and combined to produce a 39-pixel movie which can be displayed on an image processor to provide time-resolved horizontal- and vertical-focusing information.
Time-resolved measurements of the focused ion beams on PBFA II
Authors: Mix L. P. , Stygar W. A. , Leeper R. J. , Maenchen J. E. , Wenger D. F.
Published: July 2002

A time-resolved camera has been developed to image the intense ion beam focus on PBFA II. Focused ions from a sector of the ion diode are Rutherford scattered from a thin gold foil on the diode axis and pinhole imaged onto an array of up to 49 PIN detectors to obtain the spatially and temporally resolved images. The signals from these detectors are combined to provide a movie of the beam focus with a time resolution of about 3 ns and a spatial resolution of 2 mm over a 12 mm field of view. Monte Carlo simulations of the camera response are used with the measured ion energy to account for the time-of-flight dispersion of the beam and to convert the recorded signals to an intensity. From measurements on an 81° sector of the diode, average intensities on a 6 mm sphere of about 5 TW/cm2 and energies approaching 80 kJ/cm2 are calculated for standard proton diodes. Corresponding numbers for a lithium diode are less than those measured with protons. The details of the analysis and image reconstruction will be presented along with scaled images from recent ion focusing experiments.
Optical fluctuation measurements of turbulence using a diagnostic beam on Phaedrus-T
Authors: Evensen H. , Brouchous D. , Diebold D. , Doczy M. , Fonck R. J. , Nolan D.
Published: July 2002

Plasma density turbulence has been measured with the beam emission spectroscopy (BES) diagnostic system, using a low-power neutral beam with He0 and H0 as beam species. In general, He0 (588 nm) provided the best signal-to-noise ratio due to its lower edge plasma background interference. Simultaneous measurements of edge density fluctuations have been made with BES and Langmuir probes; the spectra are seen to be essentially identical, and the fluctuation amplitudes from both diagnostics are in close agreement. A poloidal coherence length of about 2–4 cm was observed. Radial propagation of modes was not seen, but a lab-frame poloidal phase velocity at r/a=0.77 of about 7×105 cm/s in the electron diamagnetic direction was observed, corresponding to m=8–75 kHz.
Response of SBDs to MeV protons, tritons, and alphas: Evidence that the charged-particle sensitive depth is not generally the depletion depth
Authors: Lo D. H. , Petrasso R. D. , Wenzel K. W. , Coleman J. W. , Li C. K. , Lierzer J. R. , Hsieh E. , Bernat T.
Published: July 2002

As part of an on-going effort to develop diagnostics for energetic charged particles from laboratory and space experiments, we examined the possibility that particle identification could be expedited by varying the applied bias voltage on silicon surface barrier detectors (SBDs). Using MeV protons, tritons, and alphas, we performed spectroscopy experiments whereby we observed changes of the energy spectrum as a function of the bias voltage. These particles were either generated via a Cockcroft–Walton linac as fusion products, or emitted from radioisotopes. The results indicate that, contrary to commonly held belief, the detector sensitive depth is not generally the depletion depth. Indeed for partially depleted SBDs the performance is not greatly degraded even for zero bias.
Thermal difference spectroscopy
Authors: Holcomb M. J. , Collman James P. , Little W. A.
Published: July 2002

We have developed a simple method of collecting the thermal derivative spectra of solids. In this method, a sample’s reflectance is measured at two specific temperatures and the thermal difference of the material’s reflectance is calculated. By digitally averaging these differences, we obtain spectra equivalent to thermal modulation spectra. Since this is not a modulation technique we have named it thermal difference spectroscopy. Using the thermal difference spectrometer we have achieved a base line noise level in the normalized thermal difference reflectance spectrum (ΔR/R) of approximately 5×10−5. To demonstrate the technique’s utility as a truly noncontact derivative spectroscopy we have collected thermal difference spectra of both thin-film and bulk samples.
A small spot Kerr photometer system
Authors: Ramesh Mahadevan , Crowell R. W. , Dey Subrata
Published: July 2002

A magneto-optic small spot Kerr photometer device with a sampling spot size in the range of 4 μm is described. Key design features of the instrument include long working distance, large air-core electromagnetic field coils, a sample holder which accommodates large samples, and a modulation detection scheme. Direct BH loops or the derivative, susceptibility signals can be obtained from a local area illuminated by the laser spot. The instrument can be used to obtain variations in magnetic properties across a large sample and is particularly suitable in wafer level testing in a manufacturing as well as research environment. Some studies done on soft magnetic films using this equipment are presented as examples of the versatility of the instrument.
High temperature reactor system for study of ultrafast gas-solid reactions
Authors: Raghunathan K. , Ghosh-Dastidar A. , Fan L.-S.
Published: July 2002

A high-temperature reactor system is developed for studying ultrafast gas-solid reactions. Time-resolved measurements of the reaction kinetics and changes in particle properties can be obtained with this system in the time scale 10–100 ms. The reactor system consists of an electrical furnace and ceramic reactor tubes, a pulse powder feed system, injection and collection probes, and a cascade impactor for in situ particle size classification. The feed system injects solids as short pulses and is capable of handling powders of size 1 μm or less. Hot jet impaction technique is used for rapid heating of the powder to the reaction temperature. The injection and collection probes are equipped with optical systems that are interfaced with a microcomputer data acquisition system, perform particle injection/sampling, reaction quenching, and optical solids monitoring. The most unique feature of the reactor system is its ability, using the probe combination, to directly measure residence times as low as 10 ms for the solids sampled from the high-temperature environment. Sample results are shown for the decomposition of limestone at 975 °C.
A high-intensity diffuse light source of ultrashort duration for reflected-light color photography
Authors: Krehl P. , Engemann S.
Published: July 2002

For use in reflected-light color photography a diffuse light source has been developed which has an annular geometry (347×140 mm in diameter) and coaxially surrounds the optical beam of recording. The light source has a luminous peak intensity of 200 Mcd and emits a flash with a duration of 180 ns FWHM. The principle of operation is based on a chain of nine V-shaped light-emitting gliding sparks, each consisting of at least 50 interstitial copper electrodes for the generation of micro gliding discharges. They are all connected in series and driven by a modified nine-stage Marx-surge generator. Substituting each V-shaped gliding spark by two U-shaped Xe-filled flash lamps doubles the light output as well as the flash duration.
A fully automated stage for loss measurements of optical waveguides
Authors: Kensky E. Thomas , Zelmon David E.
Published: July 2002

A novel test setup for making three-prism or out-of-plane scattering loss measurements for thin-film optical waveguides is described. The test structure is automated and provides quick, convenient and repeatable measurements. The setup is relatively easy to fabricate and employs several unique features which improve the accuracy and repeatability of the measurements including real-time coupling force monitoring.
Determination of ultrasound velocity and attenuation in single crystals by means of x-ray diffraction
Authors: Zolotoyabko E. , Panov V. , Schvarkov D.
Published: July 2002

A new method of determination of ultrasound velocity and attenuation in single crystals by means of dynamic x-ray diffraction is substantiated theoretically and experimentally. The diffractional response in a crystal undergoing stationary or pulsed acoustic excitation is considered. The frequency dependence of the diffraction intensity yields information on ultrasound velocity. Time scanning of the diffraction response under pulsed excitation allows one to determine the attenuation coefficient. Enhancement of the ultrasound-induced x-ray diffraction contrast is achieved for high-frequency acoustic waves, when x-ray extinction length exceeds the ultrasonic wavelength. The sensitivity and accuracy limitations of the method due to diffraction spreading of the acoustic beam, to the finite thickness of the sample and its inhomogeneity, and to lateral dissipation of the acoustic energy are evaluated. The pertinent experimental data were obtained for silicon and quartz single crystals. The advantages of the proposed method versus the conventional acoustic technique are analyzed.
Characterization of two resistive anode encoder position sensitive detectors for use in ion microscopy
Authors: Brigham Robert H. , Bleiler Roger J. , McNitt Paul J. , Reed David A. , Fleming Ronald H.
Published: July 2002

Both the standard resistive anode encoder (RAE) position sensitive ion detector and a new faster version have been adapted for use with CAMECA IMS-3f/4f imaging secondary-ion mass spectroscopy instruments. Each detector includes a dual microchannel plate image intensifier mounted in front of a resistive anode. The conversion efficiencies of the standard and fast detectors are 60% and 55%, respectively. The high count rates attainable with the fast detector require high strip-current microchannel plates for optimum performance. The mass bias of these detectors is proportional to (mass)1/2 and can be compensated by adjustment of detector supply voltage. The response across the active area of these detectors is uniform to within 3% with the greatest deviations occurring at the periphery. Distortion and pixel-to-pixel bias are negligible with the standard RAE, but noticeable in the prototype of the fast RAE. Software has been developed that corrects pixel-to-pixel bias. The dead times of the standard and fast RAE systems are 4.3±0.1 μs and 330±2 ns which limit practical count rates to about 40 000 and 600 000 Hz, respectively. For many applications, the higher ion arrival rates and dynamic range of the fast RAE imaging system more than compensate for the increased pixel-to-pixel bias and distortion and the small decrease in conversion efficiency.
Electrical conductivity measurements of corrosive liquids at high temperatures
Authors: Silný A. , Haugsdal B.
Published: July 2002

Construction of a computerized device for the electrical conductivity measurements of the liquids at elevated temperatures up to 1500 K is described. The method of four electrodes with double immersion developed by Ohta et al. extensively described in Jpn. Inst. Met. 45, (10) 1036 (1981) was selected. The greatest advantage of this method is that it eliminates the influence of the double layer capacity and all interfacial phenomena occurring during the measurement. The method should be an absolute one, but, as was found in case of corrosive melts (fluorides) at high temperatures, a calibration is necessary. The accuracy of the results obtained by this method lies in the range of ±3% and precision in range of ±1%.
Adapting a compact Mott spin polarimeter to a large commercial electron energy analyzer for spin-polarized electron spectroscopy
Authors: Huang Di-Jing , Lee Jae-Yong , Suen Jih-Shih , Mulhollan G. A. , Andrews A. B. , Erskine J. L.
Published: July 2002

A modified Rice University-type compact Mott spin polarimeter operating at 20 kV is adapted to a large commerical hemispherical electron energy analyzer. Normal energy analyzer functions are preserved via a retractable channeltron in the polarimeter acceleration column. In the spin-detection mode, the polarimeter permits analysis of two orthogonal transverse spin-polarization components. Electron trajectory analysis is used to optimize polarimeter lens column voltages in both normal and spin-detection modes. Performance levels are established by experiments and significantly improved spin-detection efficiency is shown to be accessible by changes in the polarimeter collection solid angle.
Polarization analyzing system for x-ray magnetic Kerr rotation in x-ray magnetic resonant scattering
Authors: Mori Koichi , Namikawa Kazumichi , Funahashi Yoshisato , Higashi Yasuo , Ando Masami
Published: July 2002

We made a new polarization analyzing system for measuring a rotation of major axis of elliptical polarization in x-ray magnetic resonant scattering. This system, based on a two-axis diffractometer, is characterized by introducing a 45° linearly polarized x-ray incident beam. Design and performance of the system are described. The rotation can be measured with precision of 0.2°–0.3° at the vicinity of Gd L3-absorption edge where the maximum rotation is about −2°.
New method for the measurement of gadolinium atomic beam velocity using Langmuir probes
Authors: Ogura Koichi , Shibata Takemasa
Published: July 2002

The velocity of a gadolinium atomic beam produced by electron beam heating was found to range from 700 to 1000 m/s by measuring the drift velocity of the plasma, which is produced by ionizing atoms in the atomic beam with pulsed dye lasers and using Langmuir probes. The measured atomic beam velocity spread agrees with that determined by the microbalance method.
High efficiency molecular-beam ionization detector with short ionization region
Authors: Kuhnke K. , Kern K. , David R. , Comsa G.
Published: July 2002

A mass selective electron-impact ionization detector for use in energy resolved thermal He scattering experiments is presented. The detector combines a short effective ionization region (approximately 3 mm FWHM) with a high detection efficiency of 10−5 at 2 mA electron emission. An efficiency of 10−4 at 10 mA emission current can be achieved if time resolution below 20 μs is dispensable. The design is discussed and measurements of detection efficiency and time resolution are presented. The ionizer can likewise be employed for an efficient detection of other types of atoms or molecules.
Calibration and error analysis of a new magnetic sphere microrheometer
Authors: Lewis J. L. , Burns S. M. , Samuels S. J. , Powell R. L. , Katz David F.
Published: July 2002

A magnetic microrheometer has been built, which can be used to study the rheological properties of materials that are available in small volumes and have distinct phases. The instrument performs creep tests (displacement in response to an imposed force), using magnetic microspheres of diameter 7 μm and larger. Displacement histories of the spheres are video-recorded and analyzed, with high resolution, using computer vision methods. In this article, results are presented for the magnetic force calibration and for a test using a Newtonian fluid to evaluate the performance of the instrument. A comprehensive analysis of the different sources of error in measuring Newtonian fluid viscosities was performed, resulting in quantitative delineation of the accuracy and precision of the microrheometer.