bluuebunny/crossref_metadata_2025 huggingface dataset:
New measuring system for the distribution of a magnetic force by using an optical fiber
Authors: Ishigaki H. , Oya T. , Itoh M. , Hida A. , Iwata K.
Published: July 2002

A new measuring system using an optical fiber and a position sensing photodetector was developed to measure a three-dimensional distribution of a magnetic force. A steel ball attached to a cantilever made of an optical fiber generated force in a magnetic field. The displacement of the ball due to the force was detected by a position-sensing photodetector with the capability of detecting two-directional coordinates of the position. By scanning the sensing system in a magnetic field, we obtained distributions of two-directional component of the magnetic force vector. The component represents the gradient of a squared magnetic field. The usefulness of the system for measuring the magnetic field distribution in a narrow clearance and for evaluating superconducting machine components such as magnetic bearings was verified experimentally.
Optimum extracted H− and D− current densities from gas-pressure-limited high-power hydrogen/deuterium tandem ion sources
Authors: Hiskes J. R.
Published: July 2002

The tandem hydrogen/deuterium ion source is modeled for the purpose of identifying the maximum current densities that can be extracted subject to the gas-pressure constraints proposed for contemporary beam-line systems. Optimum useful extracted current densities are found to be in the range of approximately 7–10 mA cm−2. The sensitivity of these current densities is examined subject to uncertainties in the underlying atomic/molecular rate processes. A principal uncertainty remains the quantification of the molecular vibrational distribution following H+3 wall collisions.
A compact, four-way image splitter
Authors: Murphy D. P. , Peyser T. A. , Pechacek R. E.
Published: July 2002

A compact, four-way, optical image splitter is described which maintains equal intensity and equal optical path length in each arm of the apparatus. The four output beams are parallel with the input light beam.
The minimization of ac phase noise in interferometric systems
Authors: Filinski I. , Gordon R. A.
Published: July 2002

A simple step-by-step procedure, including several novel techniques discussed in the Appendices, is given for minimizing ac phase noise in typical interferometric systems such as two-beam interferometers, holographic setups, four-wave mixers, etc. Special attention is given to index of refraction fluctuations, direct mechanical coupling, and acoustic coupling, whose importance in determining ac phase noise in interferometric systems has not been adequately treated. The minimization procedure must be carried out while continuously monitoring the phase noise which can be done very simply by using a photodiode measurement of the interferometer output. Supplementary measurements using a microphone and accelerometer will also be helpful in identifying the sources of phase noise. Emphasis is placed on new techniques or new modifications of older techniques which will not usually be familiar to most workers in optics. Thus, the necessity of eliminating the effects of index of refraction fluctuations which degrade the performance of all interferometers is pointed out as the first priority. A substantial decrease of the effects of all vibrating, rotating, or flowing masses (e.g., cooling lines) in direct contact with the optical table will also have to be carefully carried out regardless of the type of interferometric system employed.

It is recommended that this be followed by a simple, inexpensive change to a novel type of interferometer discussed in Appendix A which is inherently less sensitive to mechanical vibration. Such a change will lead to a reduction of both low-frequency and high-frequency ac phase noise by more than an order of magnitude and can be carried out for all interferometers with the exception of multiple pass optical systems and high-resolution FFT spectrometers. It is pointed out that most homemade air bladder vibration isolators are used incorrectly and do not provide sufficient reduction in the contribution of floor vibrations to phase noise. Several simple trampoline-type air bladder vibration isolator systems are described which are comparable in performance to commercial systems. With the exception of very nonrigid or undamped optical tables, the dominant source of ac phase noise at this point will usually be due to acoustic coupling to the optical components and mounts themselves. This means not only that the optical components and mounts must be rigid but that the mechanical coupling between the table and the mounts, as well as the coupling between the mounts and components themselves, be as rigid as possible.

An additional damping of optical mounts beyond that generally found in commercial mountings will also have to be carried out to obtain a further reduction of phase noise. A simple damping technique employing an additional mass and an intermediate damping layer is described which will significantly improve the performance of both homemade and commercial optical mounts. Similar damping techniques which are especially suitable for homemade optical tables and breadboards are also considered.
Removal of the plasma contained in an atomic beam produced by electron beam heating
Authors: Ohba Hironori , Nishimura Akihiko , Ogura Koichi , Shibata Takemasa
Published: July 2002

Removal of the plasma contained in a gadolinium atomic beam produced by electron beam heating was investigated. A positive or negative electric potential was applied to the plasma removal electrodes which were a pair of parallel electrodes put along the atomic beam. When a positive potential was applied to the plasma removal electrodes, the plasma could not be removed at high evaporation rates. On the other hand, the plasma could be removed by applying a high negative potential to both removal electrodes, even at high evaporation rates. The potentials applied to the electrodes required to remove the plasma were estimated using the model that a plasma at ground potential flows with the atomic beam; ions are extracted from the plasma by negatively biased removal electrodes. The estimated potentials required to remove the plasma agreed well with experimental values.
Improvements of Fourier transform phase-modulated ellipsometry
Authors: Vallon S. , Compain E. , Drévillon B.
Published: July 2002

Improvements of the Fourier transform phase-modulated ellipsometry (FTPME) technique are described. Measurements performed on the silicon oxide-silicon wafer system are used to illustrate FTPME performances. In particular, the chemistry of Si(100) and Si(111) surfaces after hydrofluoric acid (HF) treatment is investigated. Precisions on the ellipsometric angles Ψ and Δ of ±0.003° and ±0.008°, respectively, are obtained in the SiHn stretching mode region. SiH and SiH2 vibrations are identified at the Si surface revealing that submonolayer sensitivity can be achieved with FTPME. As a consequence, FTPME appears as a promising technique to perform detailed studies of interface formation and thin-film growth.
Continuous sorting of magnetizable particles by means of specific deviation
Authors: Hartig Roland , Hausmann Michael , Lüers Georg , Kraus Michael , Weber Gerhard , Cremer Christoph
Published: July 2002

A device is described that has been developed for continuous magnetic sorting of particles which are typically several micrometers in diameter. In a continuously streaming fluid, strongly magnetizable particles are deviated in a different way from weakly magnetizable particles. The strongly magnetizable particles are focused into a separate stream. The two types of particles can be collected continuously into several vials. Sorting results and applications of this technique are reported.
Investigation of silicon field-effect transistors in cryogenic amplifiers for radio frequency superconducting quantum interference devices
Authors: Becker T. , Mück M. , Heiden C.
Published: July 2002

We have prepared n-channel silicon field-effect transistors, which are capable of working at liquid helium temperatures (4.2 K) and used them in cooled preamplifiers for rf superconducting quantum interference device (SQUID) readout electronics. All metallizations of these transistors were made of niobium, to study the possibility of a further integration of a SQUID and FET on the same chip. Using the FETs in a cooled preamplifier together with a rf SQUID gradiometer, the flux noise of the system could be reduced by a factor of 3 compared to a room temperature low noise preamplifier. We have also performed calculations of a possible increase of the substrate temperature due to the power dissipation of the FET and have measured the cross talk between FET and SQUID.
1.5 GHz time-to-wavelength converter
Authors: Thomas M. C.
Published: July 2002

The time-to-wavelength converter (TWC) is a fiber-based system that converts time-dependent voltage variations in a single-transient electrical pulse into wavelength-dependent power variations in an optical carrier pulse. This system is unique because its 1.5 GHz bandwidth is independent of signal transmission distance and the optical detector is a low-bandwidth gated spectrophotometer. The TWC system uses a 50-nm-wide carrier pulse centered at 810 nm. It is capable of remotely measuring a transient analog signal with a pulse width between 0.20 and 3.0 ns full width at half-maximum and has a −3 dB bandwidth from 104 MHz to 1.56 GHz. The system’s dynamic range is 12 dB for transient signals but it can be increased to about 30 dB by averaging multiple pulses. Its operation is based on the generation of an optical carrier pulse by self-phase modulation in a flexible capillary filled with carbon disulfide; wavelength dispersion in a fused-silica single-mode fiber; optical intensity modulation using a Pockels cell; and spectral analysis of the modulated optical signal.
New instrument for microbeam analysis incorporating submicron imaging and resonance ionization mass spectrometry
Authors: Ma Z. , Thompson R. N. , Lykke K. R. , Pellin M. J. , Davis A. M.
Published: July 2002

A new reflectron time-of-flight mass spectrometer for surface analysis has been developed that incorporates a Schwarzschild all-reflecting microscope. The instrument is configured for secondary ion mass spectrometry and secondary neutral mass spectrometry using either ion beam bombardment or laser ablation for sample atomization. The sample viewing and imaging system of this instrument enables in situ laser microanalysis with a lateral resolution below 1 μm. The major advantages of using a Schwarzschild objective include good lateral resolution, easy design, low cost, complete achromatism, and both viewing the sample and extracting secondary or photoions normal to its surface. The instrument has a mass resolution of m/Δm≥2000 and is capable of measuring elemental and isotopic compositions at trace levels using resonance ionization. The isotopic ratios of trace concentrations of Ti in μm size SiC grains separated from meteorites were measured. The extremely low ablation laser power used in the above experiment points to the possibility of using low-cost laser systems for laser microprobe applications.
Emittance monitors based on Bragg–Fresnel lenses
Authors: Hartman Ya. , Tarazona E. , Elleaume P. , Snigireva I. , Snigirev A.
Published: July 2002

Two different setups for imaging an undulator source in the x-ray range have been tested. In the first, two circular Bragg–Fesnel lenses (BFL) were combined to form a telescope. The second consisted of one circular BFL and an asymmetrically cut crystal which produced vertical magnification. The emittance of the electron beam ε can then be deduced from the measured size of the source σ and the knowledge of the beta function at the source: ε=σ2/β. Effects were observed due, on the one hand, to the small aperture of the BFL and, on the other hand, to the angular emission pattern from an undulator.
Variable thickness window: Thermal and structural analyses
Authors: Wang Zhibi , Kuzay Tuncer M.
Published: July 2002

A concept that uses a variable thickness window for a synchrotron radiation beamline is proposed here for third-generation synchrotron x-ray facilities that can generate a very bright x-ray beam in a very small area. The finite difference method is used to perform the variable thickness heat-transfer analysis and variable thickness plane stress analysis. Application of the variable thickness window to an advanced photon source beamline is presented.
Initial operation of insertion devices in ELETTRA (abstract)a)
Authors: Walker R. P. , Diviacco B.
Published: July 2002

The initial operation of the first three insertion devices in ELETTRA is described, including the effects on the electron beam and analysis of the first spectral measurements. Some details are also given about compensation of the ID effects, and operation of the ID control system and vacuum chamber protection system.
Beam monitor for undulator white radiation in the hard-x-ray range
Authors: Fajardo P. , Ferrer S.
Published: July 2002

In this paper an instrument for white x-ray beam monitoring suitable for experiments with undulator beams at ESRF is presented. It is based on a 500 μm thick beryllium single crystal that is interposed in the beam. Information about the shape and position of the beam is obtained from the image of a Bragg reflection recorded by an x-ray camera. When the position is determined from a single video frame, the resolution is about 10 μm. The mosaic spread and the defects of the beryllium crystal degrade the fidelity of the beam images but do not affect the resolution of the instrument as a position monitor. The major limitation comes from the unavailability of large enough Be crystals of good quality.
Experimental characterization of ALS undulator radiation
Authors: Heimann P. , Mossessian D. , Warwick A. , Wang C. , Marks S. , Padmore H. , Kincaid B. , Gullikson E. M.
Published: July 2002

The radiation from the 5 cm period undulator at the Advanced Light Source (ALS) has been characterized using a transmission grating spectrometer. Spectral and angular distributions of radiation were measured for deflection parameter K values between 0.45 and 2.12 at low storage ring current (0.1–0.5 mA). From the calibration of the spectrometer, the absolute flux density of the undulator harmonics has been determined together with the spectral linewidth. The electron-beam emittance was determined by analyzing the angular distribution of the redshifted fundamental. Comparison has been made with radiation calculations based upon the measured magnetic-field data of the undulator. Including field errors, electron-beam emittance, and energy spread, good agreement is found between theoretically and experimentally determined harmonic widths and peak brightness.
Advanced Light Source elliptical wiggler
Authors: Hoyer E. , Akre J. , Humphries D. , Marks S. , Minamihara Y. , Pipersky P. , Plate D. , Schlueter R.
Published: July 2002

A 3.5-m-long elliptical wiggler, optimized to produce elliptically polarized light in the 50 eV to 10 keV range, is currently under design and construction at the Advanced Light Source at Lawrence Berkeley Laboratory. Calculations of spectral performance show that the flux of circularly polarized photons exceeds 1013 photons/s over the 50 eV to 10 keV operating range for current of 0.4 A and 1.5 GeV electron energy. This device features vertical and horizontal magnetic structures of 14 and 141/2 periods, respectively. The period length is 20.0 cm. The vertical structure is a hybrid permanent magnet design with tapered pole tips that produce a peak field of 2.0 T. The horizontal structure is an iron core electromagnetic design, shifted longitudinally 1/4 period, that is tucked between the upper and lower vertical magnetic structure sections. A maximum peak oscillating field of 0.095 T at a frequency up to 1 Hz will be achieved by excitation of the horizontal poles with a trapezoidal current waveform. The vacuum chamber is an unconventional design that is removable from the magnetic structure, after magnetic measurements, for UHV processing. The chamber is fabricated from non-magnetic stainless steel to minimize the effects of eddy currents. Device design is presented.
A multiple objective magnet sorting algorithm for the Advanced Light Source insertion devices
Authors: Humphries D. , Goetz F. , Kownacki P. , Marks S. , Schlueter R.
Published: July 2002

Insertion devices for the Advanced Light Source (ALS) incorporate large numbers of permanent magnets which have a variety of magnetization orientation errors. These orientation errors can produce field errors which affect both the spectral brightness of the insertion devices and the storage ring electron beam dynamics. A perturbation study was carried out to quantify the effects of orientation errors acting in a hybrid magnetic structure. The results of this study were used to develop a multiple stage sorting algorithm which minimizes undesirable integrated field errors and essentially eliminates pole excitation errors. When applied to a measured magnet population for an existing insertion device, an order of magnitude reduction in integrated field errors was achieved while maintaining near zero pole excitation errors.
A new kind of UHV piezotranslator
Authors: Mazzolini F. , Fava C. , De Bona F. , Sandrin G. , Gambitta A.
Published: July 2002

A new kind of UHV compatible microdisplacement actuator has been developed. It is based on a piezoelectric translator bakable up to 150 °C, encapsulated in a stainless-steel housing. A metal bellows allows the movement of the actuator and it gives a suitable preload to compensate the vacuum load. This new actuator has a very low outgassing rate due to the external stainless-steel surface of the casing and to the UHV electrical feedthrough. The mechanical characteristics (resolution, load capability, stiffness) are similar to those available with standard non-UHV compatible piezos. This new kind of microdisplacement actuator can be used in an UHV environment without any significant effect on the ultrahigh vacuum. The vacuum test and the accuracy test in UHV have been performed and will be thoroughly described.
A beamline for macromolecular crystallography at the Advanced Light Source
Authors: Padmore H. A. , Earnest T. , Kim S.-H. , Thompson A. C. , Robinson A. L.
Published: July 2002

A beamline for macromolecular crystallography has been designed for the ALS. The source will be a 37-pole wiggler with a 2-T on-axis peak field. The wiggler will illuminate three beamlines, each accepting 3 mrad of horizontal aperture. The central beamline will primarily be used for multiple-wavelength anomalous dispersion measurements in the wavelength range from 4 to 0.9 Å. The beamline optics will comprise a double-crystal monochromator with a collimating premirror and a double-focusing mirror after the monochromator. The two side stations will be used for fixed-wavelength experiments within the wavelength range from 1.5 to 0.95 Å. The optics will consist of a conventional vertically focusing cylindrical mirror followed by an asymmetrically cut curved-crystal monochromator. This paper presents details of the optimization of the wiggler source for crystallography, gives a description of the beamline configuration, and discusses the reasons for the choices made.
Spectroscopy beamline at the Advanced Photon Source for the photon energy region from 0.5 to 3 keV (abstract)
Authors: Randall K. J. , Gluskin E. , Xu Z.
Published: July 2002

Interest in the 0.5–3 keV, intermediate x-ray, energy region has recently intensified as this spectral region covers, among others, the important L and M edges of transition metal and rare-earth magnetic materials, respectively. Third-generation synchrotron facilities with their inherent high brightness have the unique potential to cover this energy region with high-resolution, high-flux x-ray beams ideal for spectroscopic studies. A 5.5 cm period, planar undulator to be installed on the 7 GeV Advanced Photon Source will produce a high brightness source of intermediate energy x-rays. The 0.5–3 keV spectroscopy beamline is based on the spherical grating monochromator design that has already been shown to yield high resolution and throughput in the soft x-ray region below 1 keV. The beamline has been designed to cover the entire region with a peak resolving power of 6000–10 000. Photon flux at the sample is calculated to be in the range from 1011 to 1013 photons/s into a spot size of 1 mm2. A refocusing mirror will be used to further demagnify the image size at a second experimental station. As a second phase to the spectroscopy program, an elliptically polarized insertion device will be used. The polarization preserving nature of the grazing incidence optical elements in the SGM is crucial to obtain x rays of well-defined polarization. The beamline layout, together with calculations of resolution, throughput, power loading, and high harmonic suppression will be presented. The photoemission experimental end stations for the spectroscopy station will also be briefly described. This research was supported by the U.S. Department of Energy, BES Materials Sciences under Contract No. W-31-109-ENG-38.
Explosive bonding and its application in the advanced photon source front-end and beamline components design
Authors: Shu D. , Li Y. , Ryding D. , Kuzay T. M. , Brasher Dave
Published: July 2002

Explosive bonding is a bonding method in which the controlled energy of a detonating explosive is used to create a metallurgical bonding between two or more similar or dissimilar materials. Since 1991, a number of explosive bonding joints have been designed for high-thermal-load ultrahigh-vacuum (UHV) components in the Advanced Photon Source. A series of standardized explosive bonded joint units has also been designed and tested, such as oxygen-free copper (OFHC) to stainless-steel vacuum joints for slits and shutters, GlidCop (GlidCop is a trademark of SCM Metal Products, Inc.) to stainless-steel vacuum joints for fixed masks, and GlidCop to OFHC thermal and mechanical joints for shutter face plates, etc. The design and test results for the explosive bonding units to be used in the Advanced Photon Source front ends and beamlines will be discussed in this paper.
Precision white-beam slit design for high power-density x-ray undulator beamlines at the Advanced Photon Source
Authors: Shu D. , Brite C. , Nian T. , Yun W. , Haeffner D. R. , Alp E. E. , Ryding D. , Collins J. , Li Y. , Kuzay T. M.
Published: July 2002

A set of precision horizontal and vertical white-beam slits has been designed for the Advanced Photon Source x-ray undulator beamlines at Argonne National Laboratory. There are several new design concepts applied in this slit set, including a grazing-incidence knife-edge configuration to minimize the scattering of x rays downstream, enhanced heat transfer tubing to provide water cooling, and a secondary slit to eliminate the thermal distortion on the slit knife edge. The novel aspect of this design is the use of two L-shaped knife-edge assemblies, which are manipulated by two precision X-Z stepping linear actuators. The principal and structural details of the design for this slit set are presented in this paper.
Upgrade of triple-axis/four-circle diffractometer at PF-BL3A
Authors: Takagi Yasuo , Kikuchi Toshiharu , Mizutani Toshiyuki , Imafuku Muneyuki , Sasaki Satoshi , Mori Takeharu
Published: July 2002

Several new goniometers were installed on the triple-axis/four-circle diffractometer, SIN-1 at PF-BL3A to improve data acquisition ability and beam collimation. The most prominent improvement is development and installation of a new two-circle/one-linear goniometer, which was designed to mount various x-ray detectors, such as an imaging plate or a multielement solid-state detector to acquire diffraction and/or fluorescence data over a wide range of scattering angles. The new goniometer and the original four-circle goniometer have a common rotation center (i.e., the four-circle goniometer center). The new goniometer can be operated independently of the four-circle goniometer for a wide range of scattering angles. The new two-circle/one-linear goniometer consists of a tandem combination of a translation stage, η, and two-circle goniometers, κ and ξ, where these axes η, κ, and ξ correspond to polar coordinates (ρ, θ, φ), respectively. Other improvements such as development of a pair of total reflection mirrors for the collimator axis are also reported.
A calibration standard for laser-Doppler perfusion measurements
Authors: Liebert A. , Leahy M. , Maniewski R.
Published: July 2002

The objective of the present study was the development of a new calibration standard for the laser-Doppler perfusion monitors. The beat frequency spectrum obtained from a solution of latex spheres undergoing Brownian motion was compared to that obtained from a porous polyethylene material containing the same solution. The mixture of static and dynamic scattering events in the latter case was expected to produce a spectrum similar to that obtained in the real human tissue. The results obtained demonstrate clearly the difference between the signals recorded from the commonly used motility standard which are the result of multiple Doppler shifting and homodyne mixing, and those generated from our enhanced model which predominantly result from single Doppler shifting and heterodyne mixing.
Design of high heat load white-beam slits for wiggler/undulator beamlines at the Advanced Photon Source
Authors: Shu D. , Tcheskidov V. , Nian T. , Haeffner D. R. , Alp E. E. , Ryding D. , Collins J. , Li Y. , Kuzay T. M.
Published: July 2002

A set of horizontal and vertical white-beam slits has been designed for the Advanced Photon Source wiggler/undulator beamlines at Argonne National Laboratory. While this slit set can handle the high heat flux from one APS undulator source, it has a large enough aperture to be compatible with a wiggler source also. A grazing-incidence, knife-edge configuration has been used in the design to eliminate downstream x-ray scattering. Enhanced heat transfer technology has been used in the water-cooling system. A unique stepping parallelogram driving structure provides precise vertical slit motion with large optical aperture. The full design detail is presented in this paper.
Apparatus to measure the shear modulus of Langmuir monolayers as functions of strain amplitude and frequency
Authors: Ghaskadvi R. S. , Ketterson J. B. , MacDonald R. C. , Dutta P.
Published: July 2002

We have built an apparatus to study the viscoelastic response and measure the complex shear moduli of Langmuir monolayers as functions of the frequency and amplitude of the applied sinusoidal shear strain. A rotor is placed in contact with the monolayer and suspended by a torsion wire; a coil attached to the rotor carries a direct current. The voltage induced in this coil by a high-frequency external magnetic field is used to measure the angle of rotation with an accuracy of ∼0.005°. A low-frequency external magnetic field is used to drive the rotor into forced oscillations at the desired frequency (1 mHz–1 Hz), or the rotor may oscillate freely with the “natural” frequency variable over the range 0.01–3 Hz using a static external magnetic field. The apparatus has a large dynamic range for shear modulus measurement (∼5×10−3–103 dyn/cm), achieved by using the free oscillation (ring-down) method for films with low shear moduli (∼5×10−3–1 dyn/cm), and the forced oscillation method for films with higher shear moduli (∼1–103 dyn/cm). We have found that the complex shear modulus G of heneicosanoic acid Langmuir monolayers depends on the applied strain except at very low amplitudes. We also present sample data showing the frequency dependence of G.
Probehead with interchangeable tunable bridged loop-gap resonator for pulsed zero-field optically detected magnetic resonance experiments on photoexcited triplet states
Authors: Weis V. , Mittelbach W. , Claus J. , Möbius K. , Prisner T.
Published: July 2002

Conventional zero-field optically detected magnetic resonance (ODMR) is normally performed by using a slow-wave helix for microwave excitation with a quality factor Q≈1. With available microwave sources this low Q factor leads to long microwave pulse lengths for coherent pulse experiments (π-pulse duration of about 300 ns for 20 W microwave excitation power). For our zero-field experiments we took advantage of the bridged loop-gap microwave resonator configuration with relatively high Q factor. Without the possibility of tuning the Zeeman energy level splitting as in electron paramagnetic resonance (EPR), in zero-field ODMR the resonator has to cover a wide range of frequencies. We are able to tune our probehead in the range of 1.9–8 GHz with a loaded Q factor of up to 800 by using interchangeable bridged loop-gap resonators of various designs. Thereby, the pulse lengths, compared to the slow-wave helix, could be reduced by nearly one order of magnitude (tresonatorπ=45 ns employing the same microwave power of 20 W). Experimental data are presented for triplet states of photoexcited acridine and benzophenone molecules at different resonance frequencies for their |Tx〉−|Tz〉 transitions (ν=2.472 GHz and ν=5.226 GHz), respectively.
A tandem parallel plate analyzer
Authors: Hamada Y. , Fujisawa A. , Iguchi H. , Nishizawa A. , Kawasumi Y.
Published: July 2002

By a new modification of a parallel plate analyzer, second-order focusing is obtained for arbitrary injection angles. This kind of an analyzer with a small injection angle has the advantage of low operating voltages, compared to the Proca and Green analyzers where the injection angle is 30 deg. The newly proposed analyzer will be very useful for precise energy measurements in the MeV range.
Development of an L-band electron spin resonance/proton nuclear magnetic resonance imaging instrument
Authors: Sato Toshiyuki , Oikawa Kazuo , Ohya-Nishiguchi Hiroaki , Kamada Hitoshi
Published: July 2002

An imaging instrument for measuring the 2D distribution of both free radicals and protons in a single sample was developed. A common resonator was designed for this instrument that can resonate at an L-band electron spin resonance (ESR) frequency or a HF (27.7 MHz) proton nuclear magnetic resonance (NMR) frequency. This resonator enabled construction of a simple detection block for the instrument. Because the detection processes of ESR and NMR are similar, many components, including the main magnet, magnetic-field modulation coils, field gradient coils, electrical circuits, data acquisition system, computer for reconstructing images, and most of the software were shared by these two systems. By using this instrument, both ESR and NMR images of the head of a live rat were successfully produced. The free radical distribution could be positioned by superimposing the ESR image on the NMR image.
Angle-dispersive diffraction measurement system for high-pressure experiments using a multichannel collimator
Authors: Yaoita Kenichi , Katayama Yoshinori , Tsuji Kazuhiko , Kikegawa Takumi , Shimomura Osamu
Published: July 2002

An optical device called a multichannel collimator (MCC) was developed to rapidly perform an angle-dispersive diffraction using a multi-anvil press (MAP) with synchrotron radiation. The MCC consists of multiple channels of collimators in a radial alignment. This eliminates diffraction from the materials surrounding the sample so that we can obtain high-quality diffraction from samples in a MAP using an imaging plate. We have installed a MCC system on a MAP named MAX90 at the Photon Factory, National Laboratory for High Energy Physics. Performance of the MCC has been satisfactorily evaluated, and diffraction patterns of liquid sodium and liquid gallium under 4.8 GPa have been successfully obtained using this system.
An image converting system in framing and streak mode for impulsive soft x-ray observation
Authors: Yanagidaira Takeshi , Hirano Katsumi
Published: July 2002

A high-speed image converting system is described. The system is capable of display both in multiframing- and streak-mode image for a pulsed x-ray source. The system relies on a new concept without employing an image converter tube. To achieve both temporally and spatially resolved display, the image of the x-ray source is acquired with a pinhole camera and with multichannel arrayed scintillator–photomultiplier combinations, which are used complementarily. The temporal resolution is 3 ns. This system is successfully used to observe the time evolution of soft x-ray emissions around 4 Å in plasma focus discharges with puffed Ar.
Application of the singular valve decomposition–Prony method for analyzing deep-level transient spectroscopy capacitance transients
Authors: Mazzola M. S. , Younan N. H. , Soundararajan R. , Saddow S. E.
Published: July 2002

In this article, a modified covariance method for analyzing deep-level transient spectroscopy (DLTS) capacitance transients using a combined singular value decomposition/Prony (SVD–Prony) method is presented. This combined method is based upon using the SVD method first to accurately estimate the number of exponentials contained in transient capacitance data, then the Prony method is applied to obtain an accurate estimate of the exponential time constants. Results are presented for simulated exponential data with additive white-Gaussian noise and for real DLTS data to demonstrate the applicability of the presented technique. In addition, a statistical analysis is performed to study the behavior of this technique and its effectiveness in extracting the capacitance parameters at different noise levels. Finally, the problem of multiple exponential detection is addressed.
Thermoelectric properties of the Au/Pt thermocouple
Authors: Kim Yong-Gyoo , Gam Kee Sool , Kang Kee Hoon
Published: July 2002

An Au/Pt thermocouple having a gold-bridged junction instead of a Pt coil is fabricated and its thermoelectric properties are investigated at the Sn, Zn, Al, and Ag freezing points. Reproducibility is found to be excellent and standard deviation is as small as ±4 mK at the Ag fixed point. Immersion properties, which indicate homogeneity of the thermocouple wire, are also shown to be very good, with standard deviation estimated as about 10 mK. In order to investigate interchangeability, 20 sets of Au/Pt thermocouples are made and their emfs are measured at the same fixed points. Thermocouples from the same spool are reproducible within ±0.02 °C for the whole temperature range. For practical use of the Au/Pt thermocouple, an inverse function and a deviation function for calibration are proposed. The inverse function has two temperature ranges and is accurate within ±1 mK, while the deviation function is a third-order polynomial without a constant term. The Au/Pt thermocouple is stable at high temperatures for long periods. After 1500 h at 1000 °C, the thermal emf at the Ag fixed point is changed by about 0.9 μV (about 40 mK). After the other experiments, calibration uncertainties at the fixed points are evaluated. At the Ag fixed point, the maximum expanded uncertainty is calculated and is about ±30 mK at a confidence interval of 95%. It is shown that the gold-bridged Au/Pt thermocouple is reproducible, accurate, and stable. At present, the Korea Research Institute of Standards and Science (KRISS) uses Au/Pt thermocouples as secondary standard thermometers; they are supplied to industry as certified references.
Behavior of high energy ions in the GAMMA 10 tandem mirror
Authors: Ichimura M. , Satake C. , Sakata K. , Furukawa S. , Nakamura M. , Saito T. , Tanaka S. , Kanazawa S. , Ishikawa E. , Takayama S. , Motegi S. , Saosaki S. , Nakashima Y. , Hojo H. , Tamano T. , Yatsu K.
Published: July 2002

In the GAMMA 10 tandem mirror, ion cyclotron range of frequency heating has been used effectively in the central cell. The ion temperature becomes several keV and an ion beta value is a few %. Semiconductor detectors are used for measurement of high energy protons in both parallel and perpendicular directions to the magnetic field line. Observed pitch angle distribution peaks near the cyclotron resonance layer and estimated pressure profile in the axial direction is consistent with the profile from a diamagnetic loop array. Strong temperature anisotropy can drive an Alfvén ion cyclotron (AIC) mode unstable. In a typical discharge, the temporal evolution of the endloss high energy ions has strong correlation with that of the AIC-mode amplitude. The enhancement of the loss of high energy ions due to the AIC mode is suggested.
Persistent photoconductivity and electron density dependent magnetotransport measurements in narrow InGaAs/InP quantum wells
Authors: Müller S. , Pillath J. , Bauhofer W. , Kohl A. , Heime K.
Published: July 2002

We have observed a significant persistent photoconductivity effect in narrow InGaAs/InP quantum wells grown by metalorganic vapor phase epitaxy. This effect enables a detailed study of transport parameters as a function of the electron density. In this way, the interface roughness scattering can be separated from the strongly density dependent Coulomb scattering. For different preparation conditions, we find a strong correlation between the amount of interface roughness scattering and structural data of the interface. The ratio of quantum to classical scattering times remains ≪1 even in the case when Coulomb scattering is not the predominant scattering mechanism.
An active spectrometer
Authors: Brooks N. H. , Finkenthal D. F. , Jensen T. H. , Naumenko N. N. , Tugarinov S. N.
Published: July 2002

This article describes a new type of correlation spectrometer, dubbed an “active spectrometer.” It utilizes an oscillating mirror in a 1/4-m-Rowland circle spectrometer configuration to displace the spectrum periodically in the dispersion direction relative to fixed exit slits. The wavelength of the light passing through each slit is modulated sinusoidally at the mechanical oscillation frequency and its intensity is measured with a spot detector such as a photomultiplier or photodiode. With a PC-based control/data acquisition system, the signal from each detector is sampled digitally at a frequency constrained to be an integral multiple of the mirror drive frequency. From the resultant phase locking between the signal sampling and the mirror oscillation, it follows that the correlation function between the signal and mirror phase angle is obtained simply by averaging the data from successive mirror scans. Such a scan-averaged spectrum with low noise may then be compared with digitally stored reference spectra obtained through the same instrument. ac coupling of detector and amplifier results in rejection of continuum light and, when photodiodes are used as detectors, the maximization of preamplifier gain.
A heatable large volume pressure cell for neutron powder diffraction: The Kiel–Berlin Cell II
Authors: Knorr K. , Annighöfer B. , Depmeier W.
Published: July 2002

The construction principles of a new heatable large volume high-pressure cell for neutron powder diffraction, the Kiel–Berlin Cell II, are presented. The basic design is of the piston/cylinder type. The cell is designed to operate up to pressures of 3.5 GPa and temperatures above 800 K. First tests showed the mechanical stability of the cell to be ensured up to the corresponding necessary sample load of 50 tons and a prestress of 110 tons. The cell is intended for use at reactor-based neutron sources. The use of a large sample (1.5 cm3) allows rapid data collection. There are no major geometrical restrictions in the scattering plane. The projected temperature could be reached simultaneously to the application of pressure. First neutron experiments revealed a good signal-to-noise ratio of the diffracted neutrons. For the present layout of the Ti/Zr pressure cylinders and upper stability limit of 1.2 GPa was determined.
Fabrication of single self-supported metallic nanometric wires
Authors: Laı̈ W. , Degiovanni A. , Morin R.
Published: July 2002

The fabrication of self-supported ultrathin metallic wires is described. The initial material is a Pt/Rh (10%) wire embedded inside a 50 μm diameter Ag sheath. The thinning procedure which includes mechanical, chemical, annealing, and ion milling processes, leads to diameters down to 60 nm. Each wire is curved then fixed on a dedicated support suited to all the successive preparation steps. This mechanical attachment permits a precise positioning of such a wire at micrometric distances from a flat surface and therefore, its use as an electron biprism in low-energy electron interferometry experiments. The wire thinning is limited by the creation of cusps on the wire shape.
Fluorescence intensity and lifetime measurement of free and particle-bound fluorophore in a sample stream by phase-sensitive flow cytometry
Authors: Steinkamp John A. , Keij Jan F.
Published: July 2002

We report a novel method to quantify fluorescence intensity and lifetime of free (solution) and particle-bound fluorophore in a flow stream. The technique combines flow cytometry and frequency-domain lifetime spectroscopy principles to make unique fluorescence measurements on free fluorophore and fluorophore-labeled particles. Fluorophore-labeled microspheres suspended in a fluorophore solution are analyzed as they flow through a chamber and pass across an intensity-modulated laser beam consisting of a continuous-wave (cw) direct-current (dc) and high-frequency (sine wave) excitation component. Fluorescence emission signals consisting of a dc-offset steady-state sinusoidal signal (fluorophore solution) and a sinusoidally modulated Gaussian-shaped signal pulse (fluorophore-labeled particles) are processed electronically to quantify intensities and lifetimes. The cw-excited, particle-associated fluorophore (pulse) and steady-state (dc) solution fluorescence intensity signals are measured using low-pass filtering to remove the high-frequency signal components and an ac-coupled and a gated dc amplifier to process the respective particle-bound and free fluorophore signals. The high-frequency excited, particle-bound fluorophore and free fluorophore lifetimes are individually measured using two pairs of phase-sensitive detectors to provide signals proportional to the sine and cosine of the respective phase shifts, which are ratioed to determine the respective lifetimes. The fluorescence signal intensity and lifetime detection channel outputs are displayed as frequency distribution histograms using a computer-based data acquisition system.
Solid-state pulsed power for driving a high-power dense plasma focus x-ray source
Authors: Petr R. , Reilly D. , Freshman J. , Orozco N. , Pham D. , Ngo L. , Mangano J.
Published: July 2002

Solid-state pulsed power technology has been successfully applied to a high average power dense plasma focus (DPF) x-ray point source. In the past, electrode erosion and the associated insulator lifetime have been the primary limiting factors for implementing a DPF x-ray source in a practical x-ray lithographic tool. The solid-state pulsed power supply described here uses fast-switching thyristors, diodes, and saturable magnetics to eliminate current reversal through the DPF electrodes. This has improved the DPF system performance and lifetime by reducing the electrode and insulator vaporization rates more than 20× compared to conventional sparkgap-switched drivers. Erosion measurements indicate that an electrode set can last more than 5 million shots before refurbishment. The DPF source produces an average energy of 7.3 J pulse into 4π Sr at a 1.1 keV effective wavelength in ∼1 Torr of neon gas at repetition rates up to 60 Hz. The x-ray yield efficiency is nominally 0.6%.
Simple and inexpensive interferometry of shock wave developments from pulsed high-current discharge
Authors: Takaki K. , Kobayashi T. , Fujiwara T.
Published: July 2002

Interferometer measurements are extremely informative in shock wave studies allowing direct evaluations of the gas density. The primary goal of the work presented is to build a laser interferometer that meets the requirements of the highest possible simplicity, economy, convenience, and ease of construction. In our experiments, we used a low average power (10 mW) He–Ne laser without complication, expense, and environmental section. The He–Ne laser interferometer with the Michelson arrangement was used to measure the line-averaged gas densities of shock waves. Temporal and spatial measurements of the density were performed for shock wave developments from high-current pulse discharges. The shock wave propagates in the radial direction of the discharge channel with supersonic speed. The shock velocity, however, decreased from 2–0.5 km/s with the distance of the shock propagation. The width of the high density region, that is in the vicinity of the shock front was compressed from 3.5 to 1.8 mm according to the time variation of the discharge current.
A method and technique for observing the stereo pseudocolor image of phase change of objects
Authors: Chen Guan-ying , Duan Wenshan
Published: July 2002

A real-time white light stereo pseudocolor encoding method and technique in a microscope is presented, which demonstrated that the phase information of an object is not totally lost in incoherent imaging. The image system is an improved microscope and attached optical elements can be stacked together in the microscope tube, so the structure is compact. The irradiance distribution at the output plane of the microscope is obtained by means of the theory of partially coherent light. At the conditions of that the aperture stop and focal length of condenser are a right magnitude, and the illuminative light source is incoherent or partially coherent, the theoretical analysis indicates that the irradiance distribution at output plane is presented by the stereo pseudocolor image which is characterized by the phase rate-of-change function of input object. A bleached holographic grating as an input object is observed, and its optical parameters are measured directly. Experimental results are discussed, which basically agreed with theoretical analysis.
Simulation of the thermoelastic behavior of an LLL x-ray interferometer
Authors: Bergamin A. , Cavagnero G. , Mana G. , Massa E. , Zosi G.
Published: July 2002

In order to achieve the strictest tolerances required in the manufacturing of an x-ray interferometer of the triple Laue type (LLL) to be used in the accurate determination of the silicon lattice parameter, a new shape of the analyzer crystal is considered. The simulation of its behavior proves that, if specified elastic and thermal load upper limits are satisfied, the lattice plane deformations are compatible with a measurement uncertainty of a few parts in 109.
A method for determining intrinsic shapes of overlapping spectral lines in Auger-photoelectron coincidence spectroscopy
Authors: Arena D. A. , Bartynski R. A. , Hulbert S. L.
Published: July 2002

We present a general technique to assess and remove unwanted contributions from closely spaced features in spectra acquired using Auger-photoelectron coincidence spectroscopy. We use the Ag 3d5/2 and 3d3/2 core levels and their associated core valence–valence Auger decays, the Ag M5VV and M4VV Auger lines, to demonstrate this technique. Ag M5VV and M4VV Auger spectra were obtained in coincidence with 3d5/2 and 3d3/2 core photoelectrons, respectively. We have also measured the 3d5/2 and 3d3/2 core level spectra in coincidence with M5VV and M4VV Auger electrons. In the coincidence spectra, the contribution from the spin-orbit partner is considerably reduced but, in general, not eliminated. However, by measuring all four coincidence spectra, enough information is obtained to unambiguously assess and remove the unwanted contributions and thus determine the intrinsic line shape of the M5VV and M4VV Auger lines. As a cross-check of this subtraction technique, we find that the intrinsic M5VV and M4VV line shapes give an excellent account of the conventional, noncoincidence Ag M4,5VV spectrum with the expected 6:4 ratio. The correction technique described here can be applied to a large number of systems where the close separation of core lines produces additional spectral features in the coincidence measurements of their associated Auger spectra.