bluuebunny/crossref_metadata_2025 huggingface dataset:
Monitoring of the x-ray beam intensity going through a collimator using a small ionization chamber
Authors: Bosshard R. , Kahn R. , Fourme R.
Published: July 2002

We describe a device which monitors the intensity of a collimated monochromatic x-ray beam. A small ionization chamber, mounted between the collimator and the sample, is connected to a current integrator. It is constructed and operated in order to have a linear response. Technical details about electronics are given. Two diffractometers using synchrotron radiation from bending magnets are equipped with this device, with the main purpose of rescaling diffraction data from macromolecular crystals.
The SSRL beamline data acquisition systems
Authors: Cox A. D.
Published: July 2002

SSRL has recently returned to extended running following the successful commissioning of a dedicated injector, and operation of the SPEAR storage ring exclusively for synchrotron radiation research. During the hiatus, the entire beamline data acquisition systems at the laboratory have been upgraded and extended to provide a more consistent, capable, and flexible interface to synchrotron users. Currently, 20 beamline stations have been commissioned, and planning is in the advanced stage to convert the remaining three beamline stations to use the new software set. This article outlines the design goals, implementation strategies, and capabilities of the new systems.
Computer simulation of muscle dynamics
Authors: Diaz F. G. , Pantos E. , Bordas J.
Published: July 2002

Since the early work of Huxley and collaborators [H. E. Huxley, A. R. Faruqui, J. Bordas, M. H. J. Koch, and J. R. Milch, Nature 284, 5752, 140 (1980)], time-resolved x-ray diffraction using synchrotron radiation has provided and continues to provide unique information on the structural dynamics of muscle, thus addressing the fundamental question of how chemical energy is transformed into motion. While considerable progress has been made in improving data collection procedures, relatively little progress has taken place in the development of computational methods with which to interpret the large amounts of structural and functional information contained in the experimental data. Given the characteristics of the structure of muscle this poses a considerable computational challenge since realistic models of the molecular components making up the muscle fibres require extensive algorithms and computational resources. We present here a progress report on our work on this topic and describe some of the algorithmic aspects of muscle modeling as a dynamic structure and we show how visualization techniques are used to check the effect of different factors. We also describe briefly some of the insights we have gained from the modeling procedures and ‘‘theoretical experiments,’’ and the current model that fits qualitatively the main features in the experimental pattern.
Measurements of absolute sensitivity of semiconductor detectors for 7–20 keV x rays using synchrotron radiation of VEPP-3 storage ring
Authors: Dolbnya I. P. , Mezentsev N. A. , Pindyurin V. F. , Romanenko K. P. , Subbotin A. N.
Published: July 2002

Results of measurements of the absolute spectral sensitivity of silicon semiconductor detectors for 7–20 keV x rays are presented. Synchrotron radiation from a 2-T wiggler, installed at the VEPP-3 storage ring, was used for this study. Two quite different approaches were applied to measure the detector spectral sensitivity. According to the first approach, the measurements were performed in monochromatic radiation. The absolute photon flux was determined by a scintillation counter with known detection efficiency and monitored by a transmission ionization chamber. The second approach corresponds to the measurements in a ‘‘white’’ synchrotron radiation beam through sets of known absorption filters and via the following unfolding of the spectral sensitivity from a set of integral equations. The experimental results obtained by both procedures are in good agreement. The accuracy of the experimental calibration procedures is assumed to be not worse than 10%.
Gas scintillation proportional counters for x-ray synchrotron applications
Authors: Smith Alan , Bavdaz Marcos
Published: July 2002

Gas scintillation proportional counters (GSPCs) as x-ray detectors provide some advantages and disadvantages compared with proportional counters. In this paper the various configurations of xenon filled GSPC are described including both imaging and nonimaging devices. It is intended that this work be used to configure a GSPC for a particular application and predict its general performance characteristics. The general principles of operation are described and the performance characteristics are then separately considered. A high performance, imaging, driftless GSPC is described in which a single intermediate window is used between the PMT and gas cell.
Superconducting compact sources for lithography (invited)
Authors: Wilson Martin N.
Published: July 2002

The production of advanced microchips by x-ray lithography seems likely to become the first large-scale industrial application of synchrotron radiation. Of all the possible x-ray sources, only storage rings have sufficent power to achieve economic throughputs. For this reason, many rings have been and are being built worldwide for lithography. Superconducting rings are preferred because their higher magnetic fields make them more compact.
Superconducting storage ring NIJI-III
Authors: Emura K. , Tsutsui Y. , Miura F. , Takada H. , Tomimasu T.
Published: July 2002

NIJI-III is a compact, superconducting storage ring dedicated for use in several commercial applications, especially x-ray lithography. Assembly of the ring has been completed and NIJI-III has been operating since August 1990. A beam current of above 450 mA was attained at an injection energy of 280 MeV. Currents of more than 200 mA can be accumulated at the final energy of 600 MeV.
Compact synchrotron radiation depth lithography facility
Authors: Knüppel O. , Kadereit D. , Neff B. , Hormes J.
Published: July 2002

X-ray depth lithography allows the fabrication of plastic microstructures with heights of up to 1 mm but with the smallest possible lateral dimensions of about 1 μm. A resist is irradiated with ‘‘white’’ synchrotron radiation through a mask that is partially covered with x-ray absorbing microstructures. The plastic microstructure is then obtained by a subsequent chemical development of the irradiated resist. In order to irradiate a reasonably large resist area, the mask and the resist have to be ‘‘scanned’’ across the vertically thin beam of the synchrotron radiation. A flexible, nonexpensive and compact scanner apparatus has been built for x-ray depth lithography at the beamline BN1 at ELSA (the 3.5 GeV Electron Stretcher and Accelerator at the Physikalisches Institut of Bonn University). Measurements with an electronic water level showed that the apparatus limits the scanner-induced structure precision to not more than 0.02 μm. The whole apparatus is installed in a vacuum chamber thus allowing lithography under different process gases and pressures.
Observations of a bifurcation structure in a rf driven semiconductor laser using an electronic simulator
Authors: Kao Yao Huang , Tsai Chao Hung , Wang Ching Sheu
Published: July 2002

This article presents a realization of electronic circuit to examine the dynamics of the rate equations for a directly modulated semiconductor laser. The dynamic transitions are characterized by observing the phase portraits and time evolutions of photon density and carrier density. Under the proper conditions of modulation depth and modulation frequency, the system reveals the period doubling route and bistability in various resonant regions. These are also confirmed by the numerical simulations.
Low-emittance synchrotron radiation source TNK for technology (radiation spectra and beam lines)
Authors: Korchuganov V. , Kulipanov G. , Levichev E. , Ushakov V. , Valentinov A.
Published: July 2002

The 1–2-GeV synchrotron radiation (SR) source TNK is expected to be a heart of the new Zelenograd Technological Research Center (Moscow). TNK is intended to solve submicrometer technology problems, create the base for industrial realization of advanced x-ray lithography, and to perform various x-ray structural studies within 0.2–2000 Å. The important characteristics of the facility, the features of the radiation from bending magnets and insertion devices, and SR beamline designs are described.
A beam tracking of a compact storage ring using superconducting bending magnets
Authors: Tanaka H. , Nakanishi T.
Published: July 2002

The tolerances of imperfections of superconducting bending magnets in a compact storage ring have been estimated. The storage ring, which is under construction, is a race-tracked type with combined function bending magnets. A tracking code ‘‘providence,’’ which calculates a particle’s orbit with a numerical integration of exact equations of motion has been used. The results of calculating dynamic apertures with modelized three-dimensional (3-D) magnetic fields show that multipole errors must be suppressed with (sextupole errors) ≤20[T/m2], (octupole errors) ≤110[T/m3], where the dynamic aperture is defined as a stable amplitude area with nominal aperture limitation in this paper. The dynamic aperture with actual magnetic fields has been also calculated. The result shows that the superconducting bending magnets have enough good field regions, and that the ring has a sufficient dynamic aperture: ‖x‖≂30 mm and ‖y‖≂50 mm.
High energy high resolution monochromatic x-ray computed tomography using the Photon Factory vertical wiggler beamline
Authors: Nagata Y. , Yamaji H. , Hayashi K. , Kawashima K. , Hyodo K. , Kawata H. , Ando M.
Published: July 2002

We have developed a high resolution monochromatic x-ray computed tomography system using synchrotron radiation in the energy range up to 50 keV. The system was installed in a vertical wiggler beamline (BL14C) at the Photon Factory of the National Laboratory for High Energy Physics, and consists of a double-crystal monochromator employing asymmetric Bragg reflections, a photodiode array detector with a phosphor screen, and a microcomputer for control. Computed tomography (CT) images with a pixel size of 6 to 8 μm and with a slice width ranging from 20 to 100 μm were obtained. An image subtraction technique for CT images above and below the x-ray absorption edge of iodine was also evaluated for liquid-containing glass capillaries. Since the CT value (pixel weighting) is linearly proportional to the concentration, the system can quantitatively evaluate the concentration distribution of iodine. These results indicate that the system is very useful for nondestructively evaluating fine structures and their constituent elements.
Preliminary results from a high-pressure imaging spectroscopic proportional counter
Authors: Hall C. J. , Bazzano A. , Lewis R. A. , Parker B. , Ubertini P. , Worgan J. S.
Published: July 2002

A new type of high-pressure proportional counter, with both spatial resolution and spectroscopic capabilities is being jointly developed by the Istituto di Astrofisica Spaziale (CNR), Frascati, Italy and the SERC Daresbury Laboratory, Warrington, UK. The characteristics of the detector can be optimized for the particular requirement of the experiment, either for x-ray astronomy observations from space, or for the high count rate applications associated with a synchrotron light source. In its baseline configuration, the detector is filled to 5 bar with a xenon/quench gas mixture and will be sensitive over the energy range 5 keV to 150 keV (2.5 to 0.08 Å). The positional resolution will range from 500 μm at the lower energies to around 1 mm at the higher end of the energy range. The current prototype has a sensitive area of 200×200 mm. The final version is hoped to have an area closer to 425×425 mm. The very small photon absorption length in the higher pressure gas allows the parallax effect, a feature of 1 atmosphere detectors, to be greatly reduced. The timing resolution (150 ns) of the detector enables both a high-rate capability and the possibility of the escape gate technique to achieve higher spectral resolution at energies ≳ the Xe K edge. Preliminary results are presented showing the spectral and positional resolution for the prototype detector.
Charge-coupled imagers for time-resolved macromolecular crystallography
Authors: Allinson N. M. , Colapietro M. , Helliwell J. R. , Moon K. J. , Thompson A. W. , Weisgerber S.
Published: July 2002

There exists considerable promise for the use of charge-coupled device (CCD) imagers in the fast recording of parts of macromolecular crystal Laue diffraction patterns. As part of this development CCD tests have been made with direct detection of Laue patterns from a small molecule test crystal and a protein crystal. Merging R factors (on intensity), for strong reflections, of 3% have been obtained. A time-slicing scheme for a CCD camera is discussed based on the stacking of slices held in storage in the CCD in the submillisecond time resolution range.
The one- and two-coordinate x-ray detectors
Authors: Aulchenko V. M. , Baru S. E. , Khabakhpashev A. G. , Savinov G. A.
Published: July 2002

The Institute of Nuclear Physics has designed and fabricated one- and two-coordinate x-ray detectors since 1975. For photon detection multiwire proportional chambers that operate in direct pulse count mode are employed. The characteristics of the detectors allow successful use of them for a wide range of diffractive x-ray structure studies, including studies of dynamics of structure variation (x-ray diffractive movies) and measurements at synchrotron radiation channels.
Finite element analysis of a scanning x-ray microscope micropositioning stage
Authors: Chen H. T. H. , Ng W. , Engelstad R. L.
Published: July 2002

A micropositioning stage for use with an x-ray microscope has been developed to scan samples over a 100 μm×100-μm area with a resolution of 100 Å. The stage employs flexure hinges driven by piezoelectric actuators to achieve this high positioning accuracy. Due to the severe geometry of the hinges, stresses and deflections are determined (via finite element methods) to ensure a credible design. Since the stage is to be used in a stepping capacity, natural frequencies are computed to identify resonant conditions which could potentially cause excessive deflections. The finite element models show that the stage responds like a discrete lumped-mass system for the lower modes, and a continuous system with flexural characteristics for the higher modes.
Preliminary study on the characteristics of a rf-driven H− source
Authors: McDonald D. S. , Bachman D. A. , DiVergilio W. F. , Kunkel W. B. , Leung K. N. , Williams M. D.
Published: July 2002

The use of a rf-induction discharge as a H− source is attractive for long life, pulsed, or cw operation. Recently, a new rf-driven, magnetically filtered multicusp source has been developed at LBL to generate volume-produced H− beams with extracted current densities higher than 200 mA/cm2. A total current of ∼40 mA can be obtained with a 5.6 mm diam aperture and a rf input power of 50 kW. The operating frequency is ∼2 MHz. As part of a study of the H− production mechanism in rf plasmas, measurements of the electron energy distribution have been undertaken. Initial measurements were made with a modification of the standard Langmuir probe method. The probe characteristics were sampled at different phases of the rf cycle. Results show that the electron density does not vary significantly during the rf cycle. The dependence of electron density and temperature on source pressure and axial position has been investigated and the results are summarized.
Some characteristics of the hollow-anode ion source
Authors: Miljević Vujo I.
Published: July 2002

Hollow-anode ion source with a glass discharge tube has been studied. Such a source, apart from its simple construction, is suitable for the study of the hollow-anode discharge characteristics and their influence on the ion source properties. Ion current of 1 mA (limited by the extraction power supply), when operating gas is hydrogen, has been obtained.
Negative ion beam technology for materials science (invited)
Authors: Ishikawa Junzo
Published: July 2002

Negative-ion beams can be used in materials science, i.e., ion implantation and ion beam deposition, since various types of high current negative-ion sources have recently been developed. Two types of these the NIABNIS and rf sputter types, were developed by the present authors. There are major differences between negative- and positive-ion implantations with regard to beam transport (collisional cross sections with residual gas particles) and secondary electron emission factors, but little difference in the projected ranges of implanted ions. By using negative ions in ion beam deposition, the effects of the kinetic energy and number of atoms of an ion may be clarified because negative ions have much less reactivity resulting from their internal potential energy of electron affinity than do positive ions resulting from their ionization potential.
Characteristics of an ECR ion beam source for low-pressure etching
Authors: Neumann G. , Scheer H.-C.
Published: July 2002

We have investigated an ECR ion beam source operated with a pair of coils and a two-grid extraction optics. The most important parameter for the source operation at low pressure (p<10−3 mbar) is the magnetic field in the source. A basic understanding of the physics occurring in this source can be obtained by simply registrating the total ion beam current through the first grid as a function of the magnetic field from the coils. From these characteristics we find that for the wave-propagation through the plasma column the magnet next to the microwave feed (rear magnet) is the important one. The other one (front magnet) controls the electron losses if the plasma generation is mainly located in the rear magnet. For certain magnetic field distributions we find harmonics of the ECR resonance, indicating nonlinear plasma wave interactions occurring in the source.
Insertion devices for DORIS III (invited)
Authors: Pflüger J.
Published: July 2002

Recently, a major reconstruction of the electron storage ring DORIS II, the DORIS III project, has been completed [W. Brefeld, H. Nesemann, and J. Rossbach, Proceedings of the European Particle Accelerator Conference, Rome (World Scientific, Singapore, 1988), p. 2389]. Figure 1 shows an overview of the new ring. Originally DORIS II had a twofold symmetry. In part C each of the two dipole magnets adjacing to the 65-m-long straight section was replaced by three corresponding weaker ones. In this way a total of seven straight sections for insertion devices are provided. Six of them are 4-m long and the one in the center is only 2.7-m long. After extensive discussions with the user groups involved, four x-ray wigglers, one asymmetric hybrid structure, one x-ray undulator, and one XUV multiple undulator of the revolver type have been proposed for six of the sections [J. Pflüger and P. Gurtler, Nucl. Instrum. Methods A 287, 628 (1990)]. One section is presently still free. All devices are either in construction or have already been completed and installed. In this contribution the mechanical and magnetic design of these devices will be described. Results of magnetic measurements of those devices which are already completed will be given in more detail.
Vertically and horizontally focusing beam line BL-3A of the Photon Factory
Authors: Sasaki Satoshi , Mori Takeharu , Mikuni Akira , Iwasaki Hiroshi , Kawasaki Koichi , Takagi Yasuo , Nose Kouichi
Published: July 2002

An x-ray beam line BL-3A at the Photon Factory has been designed and constructed to have optical components of a collimating paraboloidal mirror, a sagittal-focusing double-crystal monochromator, and a focusing paraboloidal mirror. The evaluation at the (+,−,−) setting of Si (111) showed that the vertical angular divergence was reduced from 13.4 to 9.5 (arcsec) by the collimating mirror. The vertical focusing with two mirrors gave the beam size of 0.2 mm (1/50). The horizontal beam size was reduced to 1/60 by sagittal focusing.
A new pulse counting low-energy electron diffraction system based on a position sensitive detector
Authors: Ogletree D. Frank , Blackman G. S. , Hwang R. Q. , Starke U. , Somorjai G. A. , Katz J. E.
Published: July 2002

A new low-energy electron diffraction (LEED) system has been constructed with a pulse counting position sensitive detector using channel plates and a wedge and strip anode. The detector accepts diffracted electrons over a 120° angle and the LEED pattern is recorded as a 256×256 pixel image. Individual LEED spot intensities can be measured up to a maximum linear count rate of ∼5 kHz while the dark count rate is ∼0.02 Hz, yielding a dynamic range greater than 105. Incident beam currents for LEED measurements are ∼1 pA. Diffuse LEED intensities from disordered systems can be measured using the large dynamic range of this instrument. Examples of diffuse LEED measurements are presented. The low incident beam currents also allow for LEED intensity-voltage measurements on surfaces sensitive to electron beam damage and on nonconducting surfaces.
A scanning tunneling microscope adapted to a 3-in. molecular-beam-epitaxy system
Authors: Stalder Roland , Gübeli Hans-Jürg , von Känel Hans , Wachter Peter
Published: July 2002

The combination of a custom-made scanning tunneling microscope with a commercial molecular-beam-epitaxy (MBE) system for 3-in. wafers is reported. The design of the microscope allows the exchange of the tip and piezo scanning unit in ultrahigh vacuum, thus offering the possibility to apply various local probe techniques with the same instrument. The tip can be cleaned by baking and by Ar+-ion sputtering. Good thermal stability and stiffness of the microscope is obtained by a lever-type design using two similar parallel piezo tubes for the scanner and for a mechanical contact close to the tip, respectively. A two-stage spring vibration isolation with internal viscous damping is used to achieve good mechanical stability for atomic-scale resolution without any further vibration isolation of the MBE system.
Two-dimensional time-resolved imaging with 100-ps resolution using a resistive anode photomultiplier tube
Authors: Charbonneau S. , Allard L. B. , Young Jeff F. , Dyck G. , Kyle B. J.
Published: July 2002

A two-dimensional microchannel plate photomultiplier with a position sensitive resistive anode has been integrated with time-correlated single photon counting circuitry. The result is a very powerful spectroscopic system which combines the very low dark count and parallel collection capabilities of the imaging tube with simultaneous timing information about the individual photon events. The digital x,y and timing information for each photon event is directly stored onto a hard-disk in real time. When the detector is placed at the output of a spectrometer, the system provides software-controllable arbitrary time windowing of complete spectra. When used as an image recorder, the system provides software-controllable time windowing of entire two-dimensional images, with ∼100-ps effective frame times.
Formation of buried oxide in silicon using separation by plasma implantation of oxygen
Authors: Liu Jingbao , Sundar Kumar Iyer S. , Hu Chenming , Cheung Nathan W. , Gronsky Ron , Min Jing , Chu Paul
Published: July 2002

Plasma immersion ion implantation (PIII) is used to fabricate buried oxide layers in silicon. This ‘‘separation by plasma implantation of oxygen’’ (SPIMOX) technique can achieve a nominal oxygen atom dose of 2×1017 cm−2 in implantation time of about 3 min. SPIMOX is thus presented as a practical high-throughput process for manufacturing silicon-on-insulator. In the SPIMOX samples prepared, three distinct modes of buried oxide microstructure formation are identified and related to the as-implanted oxygen profiles. A first-order model based on oxygen transport and oxide precipitation explains the formation mechanisms of these three types of SPIMOX layers.
Laboratory test of a LSM-based narrow bandpass and high throughput camera for Tokamak plasma imaging between 100 and 200 Å
Authors: Huang L. K. , Regan S. P. , Finkenthal M. , Moos H. W.
Published: July 2002

A narrow-bandpass (∼7 Å) and high-throughput (f/5.5) extreme ultraviolet (XUV) camera using layered synthetic microstructure (LSM) coated optics has been built and tested at the Johns Hopkins University laboratory in order to image tokamak plasma emission between 100 and 200 Å. The LSM camera was tested with a Penning ionization discharge emission source. The test measures the spectral bandpass, the spatial resolution, and the relative photosensitivities. The XUV camera will be used to measure the O vi 150 Å line brightness on the Phaedrus-T tokamak with a tangential view to investigate the impurity transport.
An x-ray target probe for superthermal electron and field line pitch measurements
Authors: Hokin Sam
Published: July 2002

An insertable target x-ray probe has been designed which may be used for two different purposes: measurement of superthermal electron temperature and drift speed, and measurement of the local magnetic field line pitch, both with fast time resolution (1 μs). The diagnostic is intended for use on the Madison Symmetric Torus (MST) reversed-field pinch. For the first application, the probe is fitted with six detectors, three viewing the part of the target facing toward the incident electrons, and three viewing the part facing away; each set of three has 0.3, 0.6, and 1.2 mil Be filters for energy discrimination. By subtracting signals from detectors with the same filter but opposing views and dividing signals from detectors with different filters but the same view, one can derive the electron drift speed and parallel temperature. For the second application, the six detectors are replaced by a single position-sensitive detector, which produces a signal indicating the position of the ‘‘hot spot’’ on the target, and therefore the field line pitch. The diagnostic can withstand high temperatures and can therefore be inserted further into the plasma than electrostatic probes.
PROMT: A multiposition Thomson-scattering system for RTP
Authors: Barth C. J. , Dirkx M. L. P. , Grobben B. J. J. , Verhaag G. C. H. M. , Wilbers A. T. M. , Donné A. J. H.
Published: July 2002

PROMT is a system for multiposition Thomson scattering in use at the Rijnhuizen Tokamak Project tokamak. Light from a ruby laser is scattered by the free electrons in the plasma and is collected along a vertical chord of 180 mm. Electron temperature and density profiles can be measured resolving up to 36 spatial elements. Scattered light is spectrally analyzed by a Littrow polychromator and subsequently detected with an intensified charge coupled device camera. At densities of 2×1019 m−3 electron temperatures in the range of 50 eV–3 keV can be measured with an accuracy of ∼5%.
Neutron time-of-flight ion temperature diagnostic for inertial-confinement-fusion experiments
Authors: Chrien Robert E. , Simmons David F. , Holmberg Dale L.
Published: July 2002

We are constructing a Ti diagnostic for low neutron yield (5×107 to above 109) d-d and d-t targets in the Nova facility at Livermore. The diagnostic measures the neutron energy spread with 960 scintillator-photomultiplier detectors located 28 m from the target and operates in the single-hit mode. Each detector can measure a single neutron arrival with time resolution of 1 ns or better. The arrival time distribution is constructed from the results of typically 200–500 detector measurements. The ion temperature is determined from the spread in neutron energy ΔEn∝Ti1/2, which is related to the arrival time spread by Δt/t≂−(1/2)ΔEn/En. Each neutron arrival is detected by using a photomultiplier tube to observe the recoil proton from elastic scattering in a fast plastic scintillator. The timing electronics for each channel consist of a novel constant fraction-like discriminator and a multiple hit time-to-digital converter. The overall system design, together with single-channel performance data, is presented.
Time resolved soft x-ray imaging with submicron spatial resolution (invited)
Authors: Willi O. , Afshar-rad T. , Desselberger M. , Dunne M. , Edwards J. , Khattak F. , Taylor R.
Published: July 2002

Recent progress in multilayered mirror technology has allowed the developments of novel imaging systems for probing of high density plasmas in the soft x-ray regime. The experimental system described here basically consists of a spherical multilayered mirror which reflects a narrow band (∓5 eV) of soft x-ray radiation in the 50 to 200 eV energy region. The mirror images either the self-emission of a laser produced plasma and/or the shadow of the expanding plasma generated by a separate laser produced x-ray source with approximately 50× magnification in the image plane and submicron resolution in the target plane. The time resolution of about 150 ps is obtained with either a gated microchannel plate intensifier as detector or a short pulse x-ray backlighter. This imaging technique has been applied to several different studies of laser produced plasmas. Measurements of the overdense plasma profiles were carried out by imaging the self-emission produced by bremsstrahlung. Two-dimensional x-ray radiographs of the density region close to the ablation surface of laser irradiated targets were recorded to observe the uniformity of the overdense plasma blowoff. The hydrodynamics of thin foil targets driven with either laser or soft x-ray radiation was investigated.
A fusion-product source
Authors: Wenzel K. W. , Lo D. H. , Petrasso R. D. , Coleman J. W. , Li C. K. , Lierzer J. R. , Borrás C. , Wei T. , Hsieh E. , Bernat T.
Published: July 2002

A Texas Nuclear Cockcroft–Walton neutron generator was refurbished for use as a general fusion-product source. This well-calibrated source is now used routinely for characterizing energetic charged-particle detectors, for the development of nuclear fusion diagnostics, for studying radiation damage, and for calibrating x-ray detectors for laboratory and space plasmas. This paper is an overview of the facility. We describe the main accelerator operating systems, the primary fusion reactions studied, and several diagnostics used to characterize the fusion-product source.
Wideband ‘‘silicon bolometers’’ on the LSX field reversed configuration experiment
Authors: Maqueda R. J. , Wurden G. A. , Crawford E. A.
Published: July 2002

Silicon photodiode detectors, which have nearly flat energy response from 1 eV to 6 keV [R. Korde and L. Randall Canfield, Proc. SPIE 1140, 126 (1989)], were used as bolometers in the field reversed theta pinch experiment LSX. Plasma escaping from the field reversed configuration is naturally diverted to the ends of the vacuum enclosure. There it affects the bolometer measurements either by direct energy deposition or by emission of low energy photons. These two particle effects can be avoided by optimizing the location of the bolometers and restricting their field of view. Good agreement is observed between the silicon bolometers and a gold foil calorimeter.
Electrostatic energy analyzer for multi-MeV heavy ion beam probes
Authors: Leisenfelder H. J. , Hickok R. L. , Resnick J. H. , Crowley T. P. , Schatz J. G.
Published: July 2002

As heavy ion beam probe energies increase, the commonly used parallel-plate energy analyzer may not be practical. A cylindrical electrostatic analyzer is being tested as a possible replacement. However, a prototype 120° analyzer failed to behave as prescribed by an ideal model that neglected fringing fields. A simulation of this analyzer, which used a detailed finite element evaluation for the fringe field, predicted the behavior and suggested that a better refocus is achieved at 108°. Simulation of a 108° analyzer is compared to experimental measurements and confirms that the numerical model correctly predicts the analyzer’s operation.
Combined energy dispersive EXAFS and x-ray diffraction
Authors: Dent A. J. , Wells M. P. , Farrow R. C. , Ramsdale C. A. , Derbyshire G. E. , Greaves G. N. , Couves J. W. , Thomas J. M.
Published: July 2002

An in situ experiment to measure both x-ray absorption spectroscopy and x-ray diffraction of aurichalcite is described. The experiment uses position sensitive detectors to enable both data sets to be collected while the sample is slowly decomposed in air and then reduced in hydrogen.
X-ray reflection properties of annealed silicon single crystals
Authors: Zaumseil P. , Winter U. , Joksch St. , Freund A. K.
Published: July 2002

We present a series of x-ray reflectivity measurements performed on annealed Czochralski grown silicon (ACS) crystals in the energy range E<50 keV using sealed tube sources. To analyze the origin of the enhanced reflectivity of this material compared to perfect, FZ-grown silicon, double and triple crystal diffractometer measurements were carried out. The results are discussed with regard to the application of ACS for monochromatization of synchrotron radiation in the mentioned energy range.
Improvement of a sagittally focusing double-crystal monochromator
Authors: Koyama A. , Nomura M. , Kawata H. , Iwazumi T. , Sato M. , Matsushita T.
Published: July 2002

Establishment of the parallelism between two axes, that of x rays and that of the cylinder made by a bent crystal, is found to be important when a sagittally focusing double-crystal monochromator is used. Detectable increase of reflection width and decrease of output intensity is observed when the angle between the above two axes becomes only 0.1°. With the help of rotation stages to adjust the axis of the cylinder, the focus smaller than 1 mm is obtained up to 11 keV at BL-6B of the Photon Factory and about 3 mm is established up to 28 keV at NE1 of the Accumulation Ring.
The secret life of image plate phosphors
Authors: Hall C. J. , Lewis R. A. , Parker B. , Worgan J. S.
Published: July 2002

X-ray imaging using storage phosphors is an increasingly popular method of taking data on synchrotron x-ray stations. There are now commercially available scanners, which are being used at Daresbury and most other synchrotron light facilities worldwide. Although the basic principle behind the x-ray stimulation and the subsequent readout of the phosphor has been known for a number of years, the details of the physical mechanisms have not been widely published and appear to be incompletely understood. Users of image plate systems might be surprised to learn of some of the observations made by the Daresbury Detector Development Group during the assessment of the storage phosphor technique as applied to x-ray diffraction on the synchrotron. We present intriguing examples of yet unexplained phenomena which may need to be taken into account for experiments with very low experimental signal-to-noise ratios in their images. Possible future developments in image plate phosphors are also discussed.
A differential scanning dilatometer
Authors: Bánó Mikuláš , Švarcberger Jiří , Lutterová Zuzana
Published: July 2002

A sensitive differential scanning dilatometer for the study of the volume changes, mainly in aqueous dispersions and solutions, is presented. The volume changes in the sample during temperature scanning are compared with the changes in a solvent at the same temperature. The metal membranes take up the expansion and change the electrical capacitance between the membranes and their surrounding electrodes. The volume of two sample chambers is 1.5 ml, the sensitivity of the instrument is 2 nl in the temperature range (0–60) °C.
Sensitive method for the measurement of the Kerr magneto-optic effecta)
Authors: Minden H. T.
Published: July 2002

Apparatus for the measurement of the transverse Kerr magneto-optic effect is described. The instrument was based on a standard research ellipsometer in a polarizer, compensator, sample, analyzer (PCSA) configuration. The light source was a laser whose intensity was acousto-optically modulated. At the same time the magnetization of the magnetic film sample was modulated by the field of a nearby coil. The frequency of the magneto-optic modulation was much less than that of the intensity. Both the intensity and magneto-optic signals were measured as functions of the analyzer and polarizer angles. The automation of the measurement is outlined. The methods are described by means of which the magneto-optic variation in ψ and Δ were calculated. Typical experimental results are presented for ferromagnetic films which were overcoated with a multilayer dielectric stack.
Easily realized inelastic electron tunneling spectrometer
Authors: Wang Y. , Mallik R. R. , Henriksen P. N.
Published: July 2002

An easily realized inelastic electron tunneling spectrometer (IETS) controlled by computer through an IEEE-488 interface bus is described. Components and circuits of the system are described in detail in order to help newcomers to IETS build a research quality spectrometer on a relatively low budget. The system design is much simpler and easier to implement than others reported in the literature, and experimental results indicate that the spectrometer has comparable resolution and signal-to-noise ratio. Additionally, in-house software routines offer the system considerable flexibility in spectral data manipulation, for example, background correction, numerical differentiation, and subtraction of one spectrum from another may be performed.
Inexpensive operating system for whispering-gallery-mode laser using dye-doped solid small spheres
Authors: Taniguchi Hiroshi , Yamada Hiroshi , Fujiwara Tamiya , Tanosaki Shinji , Baba Mamoru
Published: July 2002

A simple and inexpensive system is reported for a whispering-gallery-mode (WGM) laser using a dye-doped solid small sphere. A WGM laser is pumped by a compact transversely excited atmospheric (TEA) UV N2 laser. Experiments using the inexpensive system and some features in the WGM laser are demonstrated.
Thermal and infrared performance of a free-standing microthermocouple
Authors: Srinivas T. A. S. , Timans P. J. , Butcher R. J. , Ahmed H.
Published: July 2002

This paper discusses the thermal and optical characteristics of a free-standing microthermocouple with a view to its application as an infrared detector. This device is a radiation thermocouple in which the hot junction is thermally isolated from the substrate by making it free-standing. When radiation is absorbed by the device, the free-standing structure heats while the much larger cold junction, which is in physical and thermal contact with the substrate, remains at ambient temperature. Copper and constantan have been used as the thermocouple materials. Electrical and optical measurements have been performed for free-standing wire lengths of 20, 40, and 60 μm and have been theoretically modeled. Thermal analysis shows that convective heat loss is significant and from the measurements a convection coefficient of 20 000 W m−2 K−1, for the free-standing wires, has been deduced. The time constants of these devices were of the order of a few microseconds. The device output has been shown to depend on the polarization of the input infrared radiation. The output was largest when the free-standing wires were parallel to the polarization of the incident radiation.
Automatic high-resolution instrumentation for investigation of thermal switching in transparent ferroelastic crystals
Authors: Miga S. , Dec J.
Published: July 2002

An automatic arrangement for investigation of thermal switching in transparent ferroelastic crystals is described. The polarization microscope image converted by the CCD camera is analyzed using a PC computer equipped with a real-time video image digitizer card.
A compact electron-gun evaporation source for highly stable evaporation of refractory metals
Authors: Beag Y. W. , Egawa K. , Shimizu R.
Published: July 2002

An evaporation source of simple and compact construction was devised. This source is 20 mm in diameter and 30 mm long; is composed of a ring filament, control aperture, and disk-shaped sample (source) and shield cover; and enables the evaporation of source material to be easily controlled at a constant rate without the use of a feedback system. This evaporation source ensures depositions at constant rates for several hours. Refractory metal films of several thousand angstroms thickness can be deposited onto substrates held 10 cm from the source. Typical performance characteristics in the application to Ti films are presented.
Calibration method for the quantitative analysis of gas mixtures by means of multiphoton ionization mass spectrometry
Authors: Boesl U. , Weickhardt C. , Schmidt S. , Nagel H. , Schlag E. W.
Published: July 2002

A technique for quantitative analysis of gas mixtures in a laser mass spectrometer is presented. It is based on the addition of two calibration gases with different orders of multiphoton ionization process to the sample gas. The ratio of the signals of these two internal standards serves as a sensor for the laser intensity within the ionization volume. Thus strongly fluctuating signals due to higher-order multiphoton ionization can be normalized for every single laser shot. In addition, for such a relative measurement, effects of long-term drifts of the apparatus are eliminated. Concentrations varying from a few ppm to several percent could be determined with an accuracy better than 10% at every single laser shot. Therefore this technique allows high time resolution.
Mathematical model for predicting the molecular intensity of a solenoid-actuated pulsed beam source
Authors: Zou B. S. , Duduković M. P. , Mills P. L.
Published: July 2002

A mathematical model for evaluating the molecular intensity produced by a solenoid-actuated pulsed beam source is described. The particular source studied here is used to introduce reactant gas pulses at various user-specified intervals into a fixed-bed microreactor system for transient catalysis studies where quantification of the inlet pulse intensity is required for data analysis. The model equations which describe the beam source performance utilize relationships from one-dimensional isentropic gas expansion, gas effusion through a small hole, and macroscopic mass balances around the valve orifice from which a closed-form algebraic expression for the pulse intensity is obtained. The parameters in this expression represent observables which include the ideal gas specific heat capacity ratio, the stagnation properties of the gas in the supply chamber of the beam source, and the beam valve driver settings. Comparisons between experimental and predicted values for the pulse intensities, where the latter are of the order 1017 molecules per pulse, show excellent agreement.
A quick-retrieval high-speed digital framing camera
Authors: Sato A. H. , Yee J. , Bellan P. M.
Published: July 2002

A new high-speed digital framing camera is described. The design is built around a rotating polygon mirror that provides a framing rate of 24 000 frames/s. The camera electronics digitizes an image into a 32×104 grid of pixels, where the second dimension of the grid can be varied and is determined by the 8 bit computer-aided measurement and control digitizer sampling rate. Available digitizer memory provides for 314 frames at this horizontal resolution. The advantages over other available high-speed framing cameras are (1) low cost of the system provided the digitizers are available, (2) rapid retrieval of a recorded event, and (3) the ease with which the system can be used. Sample results from an application in high-power arc photography are given to illustrate the system’s spatial and temporal resolution.
Picosecond electrical characterization of x-ray microchannel-plate detectors used in diagnosing inertial confinement fusion experiments
Authors: Denysenko A. , Alexandrou S. , Wang C.-C. , Bradley D. K. , Donaldson W. R. , Hsiang T. Y. , Sobolewski Roman , Bell P. M.
Published: July 2002

The picosecond electrical pulse-propagation characteristics of microchannel-plate detectors, used in diagnosing laser-driven inertial-confinement-fusion experiments, were measured with an electro-optic sampling system. We determined propagation velocity and signal distortion of the microchannel-plate microstrip, as well as its characteristic impedance and the substrate relative dielectric permittivity. These parameters are critical for proper calibration of the detectors and serve as a guide for their improved designs.
Ion-sputtering atomic beam source for high-resolution laser spectroscopy of refractory elements
Authors: Wakasugi M. , Jin W. G. , Inamura T. T. , Murayama T. , Wakui T. , Kashiwabara T. , Katsuragawa H. , Ariga T. , Ishizuka T. , Koizumi M. , Sugai I.
Published: July 2002

A high-resolution laser spectroscopy system for refractory elements with an argon-ion- sputtering atomic beam source was constructed, and it has been demonstrated that the sputtering method is extremely useful as an atomic beam source for high-resolution laser spectroscopy to measure hyperfine structures and isotope shifts for refractory elements, such as Hf, Ta, and W. This source produced intense neutral atomic beams of more than 1010 atoms/s for these elements, and the yield was easily controlled by adjusting the argon-ion current and the acceleration voltage. Resonance linewidths were 32, 66, and 48 MHz for Hf, Ta, and W, respectively, which are sufficient to measure the hyperfine structures and the isotope shifts in optical transitions. With this system, the signal-to-noise ratio reached more than 106. In addition, the temperature of the sputtered atoms found was rather low compared to the kinetic energy given to the atoms.
Fabrication of optical fiber probes for nanometer-scale dimensional metrology
Authors: Marchman H. M. , Griffith J. E. , Filas R. W.
Published: July 2002

The fabrication of cylindrical probes having diameters as small as 50 nm is described in this article. The planar endface (advantageously oriented perpendicular to the axis of the cylindrical probe) and sharp 90° corners of the end portion of the probe enable accurate measurement of a feature being scanned, even at sudden jumps in the surface. Conical and flaired probes can also be fabricated with variations of this technique. The fabrication techniques described in this article are simple and inexpensive; only a Teflon beaker, optical fiber, etching solution, polymer solution, fiber cleaver, and optical microscope are necessary.
A table-top x-ray microbeam scanning facility
Authors: Attaelmanan A. , Larsson S. , Rindby A. , Voglis P. , Kuczumow A.
Published: July 2002

The x-ray microbeam scanning facility in our laboratory at Chalmers University of Technology/Göteborg University is described in terms of optical and mechanical design, imaging capacity, spatial resolution, and sensitivity. Different types of visualization of the elemental distribution are demonstrated and application of image processing is discussed. Examples of applications in the field of single-particle analysis as well as tree ring analysis are given. Future perspectives of the technique are also discussed.
Development of the National Institute of Radiological Sciences electron cyclotron resonance ion source for the heavy ion medical accelerator in Chiba
Authors: Kitagawa A. , Yamada S. , Kohno T. , Murakami T. , Muramatsu M. , Noda K. , Ogawa H. , Sato Y. , Yamada T. , Yoshizawa J. , Fu S. , Sekiguchi M. , Ohshiro Y. , Hattori T. , Shibuya S. , Matsushita H. , Sawada K. , Morishita O.
Published: July 2002

The development of an electron cyclotron resonance ion source for the heavy ion medical accelerator in Chiba (HIMAC) injector is reported. The HIMAC is a heavy ion medical accelerator for cancer therapy. The electron cyclotron resonance (ECR) ion source is expected to provide a long lifetime, easy operation, and easy maintenance for medical use. The NIRS-ECR ion source has a single closed ECR stage, and a microwave frequency of 10 GHz is applied. Under the present performance, the output electrical currents of the ions are 2500 eμA for He1+, 300 eμA for C2+, 480 eμA for Ne3+, and 110 eμA for Ar6+. Stability of the intensity is better than 2%. The transmission efficiency through a low-energy beam-transport line with an acceptance of 200 πmm mrad is more than 70%; the typical 50% and 90% emittances of the injection beam with 8 keV/u are 20 and 80 πmm mrad, respectively. These performances satisfy the requirements for radiotherapy.