bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiple modulation for optical pump-probe spectroscopy
Authors: Bado Philippe , Wilson Scott B. , Wilson Kent R.
Published: March 2003

A system built largely from readily available amateur radio gear which uses radio frequency and audio modulation of pump and probe light beams allows the detection of very weak signals (rms noise ∼3×10−11W for a 10 s time constant) even in the presence of a much larger (3.6×10−2 W) background of pump and probe light.
New algorithm for the calculation of the Fourier transform of discrete signals
Authors: Mäkinen Sakari
Published: March 2003

A new algorithm for the calculation of the Fourier transform of sampled time functions is described. The algorithm is especially applicable to the Fourier analysis of nonperiodic signals which are not band limited. The method is based on second-degree polynomial interpolations between the sample points. The obtained continuous approximation of the signal allows the determination of the Fourier transform analytically. In the case of exponentially decaying functions the algorithm was found to be significantly more accurate than the conventionally used discrete Fourier transform (DFT). The computing time is only about twice the time required by the fast Fourier transform (FFT) algorithm.
Measurement of synchrotron x-ray energies and line shapes using diffraction markers
Authors: Acrivos J. V. , Hathaway K. , Reynolds J. , Code J. , Parkin S. , Klein M. P. , Thompson A. , Goodin D.
Published: March 2003

Standard reference markers for accurate, reproducible synchrotron x-ray energies are obtained using a three Si crystal spectrometer. The first two crystals are in the monochromator and the third is used to obtain diffraction markers which monitor the energy. Then for any value of the glancing angle on the reference Si crystal the energy for the (333) diffraction must occur at 3/4 that of the (444) and 3/5 of that for the (555). This establishes for the first time an absolute synchrotron energy scale. Higher-order diffractions are used to determine excitation line profiles. We conclude that the use of reference diffractions is necessary to measure reproducible x-ray energies and to analyze the incident photons’ line profile. The detection of diffractions near the edge of measurement and near the Cu edge will provide a fast secondary standard which will allow comparison of edge data between different laboratories. The diffraction profiles will allow the proper analysis of spectral line widths.
Inhomogeneous-field stripper for field ionization detection and analysis of fast beams of highly excited atoms
Authors: MacAdam Keith B. , Rolfes Richard G.
Published: March 2003

A new device is described for detection, dispersion, and analysis of keV beams of highly excited atoms. Field-ionization events are electrostatically tagged by inhomogeneous electric fields in a cylindrical geometry. State identification is based on the relationship between ionizing fields and atomic-state quantum numbers. Calibration is accomplished by injecting fast beams of selectively excited Na atoms into the stripper. Application of the detector to measurement of charge transfer from Rydberg atoms is demonstrated.
Improved control of a bleachable dye Q switch
Authors: Paul S. F.
Published: March 2003

Bleachable dyes, when used as laser Q switches, are very fast and inexpensive, but synchronization with external events is difficult because the mechanism is passive. The time at which switching occurs depends on the time history of the laser rod fluorescence which in turn is critically dependent on the flashlamp energy, temperature, and laser alignment. Techniques to reduce the uncertainty in the timing of the laser pulse are presented. Laser pulse widths of less than 100 ns, with pulse energies of ∼1 J, and timing errors of ∼3 μs are achieved with the described dye Q switch. Methods to further reduce ’’jitter’’ are given.
Length measurement using infrared two-wavelength He–Xe laser interferometer
Authors: Matsumoto Hirokazu
Published: March 2003

The results of length measurements made with a 800-mm-long gauge block, using an infrared interferometer whose light source is a 3.51– 3.37-μm simultaneous operation He–Xe laser, are described. The wavelength ratio of the 3.51-μm line to the 3.37-μm line is determined to an accuracy of 1.7×10−8 and the absolute length of the gauge block is uniquely determined to an accuracy of 4.9×10−8 by the method of excess fractions. This interferometer has a possibility of measuring lengths up to several meters.
Comparison between an amplitude-measuring wire and a slope-measuring laser water wave gauge
Authors: Lange P. A. , Jähne B. , Tschiersch J. , Ilmberger I.
Published: March 2003

Capillary waves produced in a laboratory wind wave tunnel have been measured using a wire resistance-type gauge (measuring wave amplitude) and a laser gauge (measuring wave slope). Comparison of power spectra of the gauges shows good agreement to 80 Hz, which is the upper frequency limit of the wire gauge. The upper frequency limit of the laser gauge depends upon laser beam diameter and is about 300 Hz.
Versatile microprocessor data logging and processing system for laser Doppler anemometry
Authors: Fanton Jean-Claude , Lisé Bertrand , Boulos Maher
Published: March 2003

A description is given of the design and performance of a versatile microprocessor data-acquisition system used for the logging and processing of counter-type laser Doppler anemometry data. The system with a 32-K of RAM can handle up to 10 000 data points. The statistical analysis carried out involved the determination of Vmin, Vmax, V̄, and σ together with the complete probability density distribution function. In order to allow for the repeated analysis of the same data file using different numbers of data points and velocity limits, care was taken not to destroy the original data files during the analysis. The use of an arithmetic processor unit reduced the processing time of the data by almost one order of magnitude. Under typical operating conditions, the system performed a complete statistical analysis of 10 000 data in about 28 s.
Use of laser-generated acoustic pulses to measure the electric field inside a solid dielectric
Authors: Migliori A. , Hofler T.
Published: March 2003

We describe a technique for measuring the electric field inside solid dielectrics and apply it to a polymethylmethacrylate sample. The technique uses a laser-generated acoustic pulse to deform the sample inhomogeneously in a nondestructive, nonperturbing manner. From the electrical response of the sample during deformation, the macroscopic electric field as a function of position may be calculated. We achieved a sensitivity of 5×104 V/m and a spatial resolution of 50 μm in a 3-mm-thick sample.
New technique for mapping heat-transfer coefficient contours
Authors: Simonich J. C. , Moffat R. J.
Published: March 2003

A new technique for mapping heat-transfer coefficient contours quickly and easily is presented. The technique utilizes cholesteric liquid crystals to infer surface temperatures. The tests conducted to ’’qualify’’ the technique for quantitative determination of heat-transfer coefficient are outlined. The experimental results obtained from this technique in simple flow situations are compared to measurements taken with conventional techniques. The frequency response of the instrument to fluctuations in heat-transfer coefficient is shown to be at least 1.3 Hz.
Measurements of neutralization efficiency of a 50-keV He+ beam in a He gas cell
Authors: Green T. S. , Holmes A. J. T.
Published: March 2003

Measurements of the power loading in some ion sources indicate that the gas inside the plasma generator of the ion sources is heated by energy and momentum exchange with the plasma ions. This hypothesis is tested by measuring the gas target thickness by the conversion of He+ beam ions to He0 by a neutralizer cell which is fed with gas from the plasma generator. The gas temperature can be derived directly from the measured gas target as the gas conductance is known. A control experiment is also made when the gas feed to the neutralizer is from an external supply.
Photochron IV subpicosecond streak image tube
Authors: Sibbett W. , Niu H. , Baggs M. R.
Published: March 2003

The electrode configuration and electron-optics of a newly designed streak image tube (Photochron IV) are described. The results of our theoretical studies show that the Photochron IV can have a limiting temporal resolution ∼0.2 ps when the photocathode is illuminated near the long wavelength cutoff and subpicosecond resolution ≲0.5 ps in the UV/visible/NIR spectral regions and ∼1 ps for 1-keV x rays. This streak tube design also possesses the features of a good dynamic range and reduced temporal distortion.
Programmable output intensity controller for monochromators
Authors: Ramadan B. , Leung Y. K. , Kos J. F.
Published: March 2003

The design of a progammable monochromator output controller is presented. It can be programmed to produce a constant intensity light beam as a function of wavelength from 300 to 1100 nm. Alternately, it may be programmed to produce any desired intensity vs wavelength output. This feature has been applied to simulate the solar spectrum between 300 and 1100 nm. The latter capability may find an important application in the testing and precise characterization of solar cells.
Sensitivity and response time improvements in a millimeter-wave spectrometer
Authors: Kolbe W. F. , Leskovar B.
Published: March 2003

An improved microwave spectrometer for the detection of gaseous pollutants and other atmospheric constituents is described. The spectrometer, which operates in the vicinity of 70 GHz, employs a Fabry–Perot resonator as a sample cell and uses superheterodyne detection for high sensitivity. The instrument has been modified to incorporate a frequency doubler modulated at 30 MHz to permit operation with a single Gunn oscillator source. As a result, faster response time and somewhat greater sensitivity are obtained. The spectrometer is capable of detecting a minimum concentration of 1 ppm of SO2 diluted in air with a 1-s time constant. For OCS diluted in air, the minimum detectable concentration is 800 ppb and with a 10-s time constant 300 ppb.
Improved technique for measuring transient changes in microwave cavity Q and resonant frequency
Authors: Amato J. C.
Published: March 2003

We describe an adaptation of a previously published technique for measuring transient changes in the Q and resonant frequency of a microwave cavity. The new method achieves high sensitivity by making use of computer-generated numerical solutions to the nonlinear equations for ΔQ and Δf0.
Simple and efficient monoenergetic electron source
Authors: Proulx M. , Marmet P. , Dutil R.
Published: March 2003

A source of monoenergetic electrons giving a high electron current (3×10−8 A) simultaneously with a good energy resolution (30 meV) is described. It has been ascertained that the emitted electron beam is not superimposed on a background which normally appears when an electron beam is scattered on deflecting electrodes within the instrument. This double 127° cylindrical selector is especially suitable for experiments where relatively high intensities in conjunction with high quality beams are essential and where stable electron currents over periods of several days or weeks are required. Such a stability is observed in the case where the gas pressure inside the selectors is as high as 10−5 Torr.
Acoustic levitating apparatus for submillimeter samples
Authors: Lee Mark C. , Feng I-an
Published: March 2003

A hemispherical focusing radiator has been employed to generate ultrahigh intensity sound waves in a gaseous medium at the center of curvature of the radiator (focal point) at 75, 107, and 163 kHz. A volumetric force is produced by optimally placing a reflector in the vicinity of the focal point to levitate samples of submillimeter sizes. It has been demonstrated that a sample with a specific gravity of 19.3 can be levitated with this apparatus. The lateral positional wandering of the sample in the force well is estimated at less than 5% of the dimension of the sample size used.
Apparatus for determining the thermal properties of large geologic samples at pressures to 0.2 GPa and temperatures to 750 K
Authors: Abey A. E. , Durham W. B. , Trimmer D. A. , Dibley L. L.
Published: March 2003

An apparatus has been designed and fabricated to measure the thermal diffusivity and thermal conductivity of relatively large geological samples in the pressure range to 0.2 GPa and the temperature range from 300–750 K. Data on a domal salt from Avery Island Mine in Southern Louisiana are presented as examples of the results obtainable from the apparatus.
Practical model for the design of step heat exchangers
Authors: Rosenbaum Ralph , Breuer Ami
Published: March 2003

A simple analysis is presented for modeling step heat exchangers for the dilution refrigerator. The model incorporates the effects of external heat leaks and the Kapitza boundary resistance. Theoretical temperatures of the heat exchangers and of the mixing chamber are in acceptable agreement with experimental results. Predictions suggest that temperatures of 6 mK can be achieved using three-step heat exchangers and a He3 circulation rate of 90 μmoles/s.
New look at solder-sealed liquid helium cryostats
Authors: Claassen J. H.
Published: March 2003

A new design for a solder-sealed demountable vacuum can that can be cycled to liquid helium temperature is described. This design is the basis of a ’’dip probe’’ used with a commercial helium storage Dewar that permits rapid turnaround cryogenic measurements at temperatures above 4.2 K. It has significant advantages over gasket-sealed designs from the standpoint of bulkiness, weight, and reliability.
Efficient collection of Raman-scattered light
Authors: Graham Daniel J. , Mushlin Richard A.
Published: March 2003

The design and implementation of a device used for Raman-scattering experiments are reported. This device, namely an optically reflecting bulb, has been found to serve as an efficient collector of light scattered by a sample located at its center. It can be constructed easily and inexpensively and can be used for both room- and low-temperature experiments. A second device which makes use of maximum reflecting surface area and a light pipe is also described.
Differential reflectometer for studies of adsorption on stepped crystal surfaces
Authors: Wolterbeek L. , Hottenhuis M. H. J. , Kuper F. G.
Published: March 2003

A differential reflectometer is described which is capable of measuring reflectivity variations down to 0.05% of those very small fractions (10−2–10−3) of the illuminated surface that are of interest, i.e., atomically stepped parts of rough or curved surfaces that have a certain orientation and reflect light into a certain direction. The intensities of the incident beam and the light reflected over a certain angle, differing by several orders, are equalized at the point of detection by optical means in order to meet the requirements of accurately determining their ratio. Apart from the glass fiber bundle, which picks up the reflected light, the same optics are present in incident as well as reflected beam paths according to the reflectometer principle. The experimental setup has been tested by measuring the adsorption speed of oxygen on rough cleaved silicon surfaces which consist of parts with varying densities of monoatomic steps.
Temperature-compensated, differential tensimeter for measuring gas adsorption by low surface area solids
Authors: Suzuki Isao
Published: March 2003

An apparatus is described which permits convenient determination of gas adsorption of solids having lower adsorption capacity at subatmospheric pressures. The apparatus consists of a differential micromanometer whose two arms are connected to a pair of sample and reference burets of nearly equal volume for dosing gas into sample and reference cells also of nearly equal volume. When the two cells are immersed in the same temperature bath this design greatly reduces measurement uncertainties due to fluctuations in temperature. Surface areas as small as 1000 cm2 can be measured through volumetric measurements of nitrogen uptake at overall pressures between 3 and 30 KPa at liquid nitrogen temperature.
Technique of range modulation for a clinical pi-meson beam
Authors: Lam Gabriel K. Y.
Published: March 2003

A simple, versatile technique of range modulation has been developed based on the mathematical technique of linear programming for linear addition of depth dose curves. This technique enables the use of discrete step range shifting, and hence results in substantial simplification in the design and operation of range modulators. A prototype using only eight steps has been constructed for the TRIUMF biomedical π− channel for cancer radiotherapy. This system has been shown to be capable of producing depth dose profiles of various characteristics required for biomedical experimentation. Its operation under computer control is also simple, accurate, and immune to large fluctuations in the output of the TRIUMF accelerator.
Simple method of measuring delay time in manufacturing delay lines
Authors: Kasahara Yukio , Mikoda Masanari
Published: March 2003

A simple method for measuring delay time in an operational frequency range is required in manufacturing delay lines used for video tape recorders and television receiver sets. This paper describes a simple method of measuring and adjusting the delay time of such delay lines. The delay time is obtained by measuring a phase difference ϑ between the signals at the input and output transducers of the delay line with frequencies under test. The delay time is more precisely obtained by measuring the ϑ at a constant frequency within the bandwidth of the delay line. A delay-time tolerance of a polished glass medium at 3.58 MHz was found to be within 100 ns. The delay time was found to be shortened by 30 ns by attaching the medium on polishing powder and oil. Also shown is a simple method for adjusting the delay time by polishing a delay medium while measuring the phase difference.
High-pressure high-temperature differential scanning calorimeter
Authors: Sandrock R.
Published: March 2003

A new high-pressure differential scanning calorimeter for investigations in the temperature range from 300 to 600 K and pressure from 10 to 6000 bar is described. The calibration procedure for the temperatures and the heats of transition is discussed. Some results on diamantane are presented.
Simple digital integrator and pulse counter
Authors: Shoemaker James O. , Carr Robert W.
Published: March 2003

A simple and inexpensive digital circuit for pulse counting and integration of signals from a disc calorimeter, used for pulsed laser radiant energy measurements, is described.
Simple microcomputer-based apparatus for combined DLTS–C-V measurement
Authors: Asada Kunihiro , Sugano Takuo
Published: March 2003

A very simple high-performance microcomputer-based apparatus for the combination of DLTS and C-V curve measurements is reported here. This apparatus has an A/D converter instead of gated boxcar integrators and a D/A converter instead of a pulse generator, both of which are controlled by an eight-bit microcomputer. An analog feedback loop for CCDLTS is replaced by a digital control loop which does not appear in hardware. This has been done by developing an adaptive feedback gain control algorithm for the control program of the microcomputer. All data required for DLTS analyses such as the determination of energy levels, thermal emission rates, and in-depth profiles of deep traps can be obtained in a single temperature scan using the multipoint measurements of the capacitance transient (DLTS mode) performed repetitively with different filling pulse voltages. The acquisition capacity of this apparatus in a single temperature scan is about 50 times higher than that of a conventional one, which uses double boxcar integrators. In addition, C-V curve measurements (C-V mode) can be done in DLTS mode in 20 K intervals.
Birefringence measurements of crystalline polymers using a far-infrared interferometer
Authors: Jacobsson Stellan , Hård Sverker
Published: March 2003

It is demonstrated that far-infrared interferometry can be used successfully to measure birefringence of crystalline polymer samples thick enough to be opaque at visible wavelengths. The use of a strong, optically-pumped laser as a source of radiation allows absorbing plastics to be measured. An injection molded, high-density polyethylene specimen showed a birefringence of about 2%, whereas a compression-molded sample of the same material showed no measurable birefringence.
Novel directional ion energy analyzer
Authors: Stenzel R. L. , Williams R. , Agüero R. , Kitazaki K. , Ling A. , McDonald T. , Spitzer J.
Published: March 2003

A new ion energy analyzer with high angular resolution (⩽3×10−4 sr) is described. It consists of a microchannel plate followed by a retarding-grid type analyzer. The microchannel plate is not used for charge multiplication but as a geometric filter with narrow angular passband (ϑ≃0.6°) yet high transparency (T≃60%). The energy analyzer is used to measure the true velocity space distribution of low-energy ion beams (Eb = 10–100 eV) in a double plasma device. Its superior performance over the conventional gridded energy analyzer is demonstrated. Applications to the study of beam wakes are shown.
Apparatus for determining the polarity of piezoelectric crystal blanks
Authors: Gualtieri D. M.
Published: March 2003

An apparatus is described which allows the rapid determination of the polarity of cut blanks of piezoelectric crystal. Features include automatic balancing, high sensitivity, high noise immunity, operation from a unipolar power supply, and simplified display.
Design, construction, and testing of a nuclear-pumping facility at the University of Missouri Research Reactor
Authors: Lecours Michael J. , Prelas Mark A. , Gunn Steven , Edwards Chester , Schlapper Gerald
Published: March 2003

An intense effort to design, construct, and test a nuclear-pumping facility (NPF) has been completed at the University of Missouri-Columbia (UMC). The NPF has a flow capability similar to that of the now defunct Brookhaven Chemonuclear In-Pile Research Loop, plus the optical capability to monitor light output from the irradiation chamber. Both features make the UMC NPF a unique research loop usable for a wide variety of projects including radiation chemistry, fluorescence studies, photochemistry, dual media nuclear-pumped lasers, and direct nuclear-pumped lasers. Initial tests of the facility included a demonstration of 40.0 ft3/h flow rates (pump limited), and a spectral scan of N2 and He. The latter test represents a first effort in obtaining nuclear-pumped gas spectra from a high-power steady-state reactor such as the University of Missouri Research Reactor (MURR). Results indicate that observed spontaneous emission mainly comes from the first negative spectral series in N2+ (B2Σ+u →x2Σ+g) and from He*2 electronic transitions.
Description of an electronic controller used with an autocorrelator to measure a femtosecond pulse duration in real time
Authors: Kalpaxis A. , Doukas A. G. , Budansky Y. , Rosen D. L. , Katz A. , Alfano R. R.
Published: March 2003

An electronic circuit controller is described which is used with an autocorrelator and an oscilloscope to measure the duration of femtosecond laser pulses in real time. The controller drives both the autocorrelator and the oscilloscope to produce a linear trace display of a pulse autocorrelation function on an oscilloscope. The apparatus has been found very useful for monitoring, aligning, and characterizing the output from cw mode-locked dye lasers.
Point-contact electron tunneling spectrometer
Authors: Leo V.
Published: March 2003

In this paper we present the description of a point contact spectrometer which allows us to realize tunnel junctions (sample/Al oxide/Al) by mechanically approaching the sample (mounted as a moving electrode) to an oxidized Al counterelectrode. Due to the design, the careful choice of materials, and the use of a very accurate driving system (with an approach detecting feedback) this spectrometer is extremely efficient over a wide temperature range. The particular geometry makes possible the study of tunnel characteristics on single crystals of compounds that do not stand vacuum evaporation, usually involved in standard thin-film tunnel technique.
Accurate scaling of rf frequencies to a few Hz
Authors: Menders J. , Diels J.-C.
Published: March 2003

A rf scaling circuit is described which can generate a low-frequency signal of a few Hz synchronized with frequencies of nearly one GHz. The period of the low-frequency signal is accurate to within one period of the rf signal and has a phase jitter observed to be a fraction of a nanosecond.
Simple method for producing durable ultrathin windows for use in x-ray microradiography
Authors: Dunsmuir J. H. , Varon J.
Published: March 2003

A method for preparation of durable, optically opaque, ultrathin laminates of metal and polymer for use as soft x-ray windows in contact microradiography is described. Specifically, thin copper layers produced by sputtering have been laminated on formvar supports to yield films with significantly improved Cu Lα transmission over 0.5-mil Be windows. Improvement in the spectral purity of the transmitted radiation is also expected due to filtering.
Multichannel surface arc switch
Authors: Cohn D. B. , Conley E. E.
Published: March 2003

A simple, multichannel surface switch has been developed suitable for pulse generators commonly used for TEA laser excitation. Switch voltages over the range 15–35 kV were successfully tested. Low energy, auxiliary discharge triggering was found to increase arc channel number density under some circumstances.
Simple sample cell for deoxygenation of surfactant solutions
Authors: Buell Scott L. , Demas J. N.
Published: March 2003

A simple gas bubbling system for removal of dissolved oxygen in micellar and surfactant solutions is described. The cell design allows for a continuous rapid flow of a purge gas through a surfactant solution without loss of fluid in spite of severe foaming. A long-necked cell with a conical top causes the bubbles to rupture without overflowing, and the fluid returns to the bulk solution. The cell offers numerous advantages over freeze pump thaw and other methods of deoxygenation in terms of speed, ease of sample preparation, and cost.
Soft x-ray measurements from the PDX tokamak
Authors: Silver E. H. , Bitter M. , Brau K. , Eames D. , Greenberger A. , Hill K. W. , Meade D. M. , Roney W. , Sauthoff N. R. , Von Goeler S.
Published: March 2003

Temporally and spatially resolved profiles of the PDX soft x-ray spectra have been measured during single tokamak pulses of circular divertor plasmas with a recently developed pulse-height analyzer. This detection system incorporates an array of five vertically displaced sets of lithium-drifted silicon detectors, each consisting of three independent channels optimized for rapid data collection in adjacent energy regions. Simultaneous measurements of x-ray emission integrated along five chords of the plasma cross section can, thereby, be achieved. Abel inversion of these data yields temporally resolved radial profiles of the local electron temperature from the slope of the continuum, concentrations of high-Z impurities from the characteristic line intensities, and a measure of Zeff from the continuum intensity. The techniques of x-ray pulse-height analysis, with illustrations featuring the results from the initial PDX circular plasma experiments, are discussed in detail. In addition, comparisons between circular and divertor plasmas on PDX, derived from the x-ray measurements, are also presented.
Response of CR-39 to 2-MeV microbeams of H, He, and Ne
Authors: Lefevre H. W. , Sealock R. M. , Connolly R. C.
Published: March 2003

CR-39 (allyl diglycol carbonate), a plastic track detector, has been irradiated with 2-MeV microbeams of H, He, and Ne in order to assess the usefulness of this detector for microbeam diagnostics. Optical microscopy, laser diffraction, and etching were used to examine the samples. A decrease in index of refraction, sufficient to make the radiation damage visible without etching, occurs for threshold doses between 5×104 and 5×105 particles/μm2 on beam spots 20 μm in diameter. Saturation of optical changes occurs at doses between 5×106 and 5×107 per μm 2. Diffraction intensity and optical activity were observed to develop with a time constant of several minutes after a short exposure. Below saturation, the developed diffraction intensity varies as the 1.5 power of dose. Relative diffraction intensities at a dose of 3×105/μm2 for H, He, and Ne are 1:14:93. The unetched detector is highly useful for in situ observation of beam-spot shape. Etching the detector can reveal many unexpected features.
Calibration of a Mn-activation detector for intense pulsed energetic neutron sources
Authors: Young F. C. , Pronko J. G.
Published: March 2003

A simple Mn-activation detector for pulsed MeV neutron sources with intensities exceeding 1011 neutrons/pulse is described. Absolute calibration of the detector using neutrons from the 7Li(p,n)7Be reaction is determined as a function of the distance from the source.
Superconducting susceptometer for high-accuracy routine operation
Authors: Vitale S. , Morante S. , Cerdonio M.
Published: March 2003

We present a new version of a SQUID susceptometer with the following performance. The overall accuracy is δχ≃3×10−9 (SI units). Within this figure is allowed the reproducibility in interchanging samples, the thermal expansion of the samples up to 10%, and the constancy of the calibration over a time scale of months. The sample can be interchanged in minutes and the overall time taken by the actual measurement procedure, to give results within the accuracy quoted above, is of the order of 5 min for one sample at one temperature. The temperature regulation is precise within 0.2 K between 40 and 300; the accuracy in the sample temperature has been tested to be within 0.5 K in the room temperature range. This performance is of great relevance for studies of biological molecules in solution, when different samples in different solution conditions must be compared with accuracies better than parts in a thousand of the magnetic susceptibility of the solution.
Low-temperature thermometry in high magnetic fields. V. Carbon-glass resistors
Authors: Sample H. H. , Brandt B. L. , Rubin L. G.
Published: March 2003

The characteristics of carbon-glass resistance thermometers for temperatures from 2.15 to 320 K and in magnetic fields of up to 19 T are described. The results from nine thermometers made from six different batches of raw material are combined to produce mean values that may be used to correct a ’’typical’’ thermometer at 19 T to within ±0.1% in temperatures between 30 and 320 K, and to within ±1% between 2.15 and 30 K. All nine sensors show a small orientation dependence of their magnetoresistance at 77 K; two out of four tested have an experimentally significant dependence at 4.2 K. The temperature error corresponding to the magnetoresistance of a miniature precision platinum resistance thermometer at 19 T is less than for carbon-glass sensors above 77 K. New recommendations are made for the optimum use of low-temperature thermometers in high magnetic fields.
Preparation of long-lived excited ions for lifetime measurement by selective electron capture
Authors: Winter Hannspeter
Published: March 2003

Lifetimes of long-lived excited singly or multiply charged ions can be measured by producing the latter via selective electron capture in collisions of slow multiply charged ions and neutral particles, and determining the decay characteristic of radiation emitted along the flight path of excited ions. As an example, ’’metastable’’ Ne+(3s4P) ions were produced by utilizing the impact of Ne+2 on Xe at an impact energy of 51.5 keV. For the shortest lived state, which probably corresponds to j = 3/2, a lifetime of 100±20 ns was obtained.
Flash ADC time-of-flight spectrometer
Authors: Egan Patrick O. , Woodle Kim
Published: March 2003

We describe a time-of-flight spectrometer based on the direct readout of a 7-bit, 15-MHz flash ADC. The wide dynamic range of this device leads to several advantages over conventional time-of-flight methods, particularly with regard to noise reduction. The performance of a CAMAC-based flash ADC/RAM unit for low-energy electron time-of-flight measurements is described.
Surface probe for measurement of liquid contact in film and transition boiling on high-temperature surfaces
Authors: Lee L. , Chen J. C. , Nelson R. A.
Published: March 2003

A microthermocouple probe to detect liquid contacts on a high-temperature surface during film and transition boiling regimes is described. Experiments indicate the probe and its associated data recording and processing circuits have sufficiently rapid response to provide quantitative measurements of individual liquid contacts, permitting calculations of contact frequencies and durations, and of average vapor versus liquid contact time fractions. Initial experimental results for pool boiling of saturated water at atmospheric pressure, in the quenching of a high-temperature copper block, indicated that the liquid contact time fraction increased from 10% to 65% in 7 s as the block surface temperature cooled from 483 to 418 K.
Linear sensor image processor
Authors: Kebedjiev A. G.
Published: March 2003

A circuit processing the video output information of a linear image sensor, used as a monitor in a control system, was developed. The circuit is sensitive to the position of the image with respect to the sensor, and if the image goes out of viewing range, the feedback loop locks safely.
Current distribution measurements on the cathode of a transient plasma column
Authors: Decoste R. , Drouet M. G.
Published: March 2003

A simple technique is used to measure the time evolution of the plasma current distribution at the cathode during a fast reversal of the arc current. Radial profiles of the current are inferred from pictures of cathode spot distributions recorded by a fast framing camera. Limitations of the technique are discussed in the context of fast current variations.
Etch decoration—scanning electron microscopy technique for measuring carbon gasification rates
Authors: Yang Ralph T. , Wong Chor
Published: March 2003

Transmission electron microscopy has been used for some important discoveries underlying gas-carbon reaction kinetics. This technique requires cleavage of the sample to about 700 Å thickness. This study demonstrates that the same results by TEM can also be obtained by a much easier technique using scanning electron microscopy. Furthermore, the SEM technique is applicable to uncleavable materials and provides additional microscopic information on the surface.
Further reflections on the role of a mass flux gauge in the calibration of mass spectrometers for dimers
Authors: Fenn John B. , Lee Naisin
Published: March 2003

As Gentry’s analysis demonstrates, mass flux gauge data are not a complete solution to the problem of calibrating mass spectrometers for dimer concentration measurements. However, they can provide information of value in estimating the minimum extent to which dimers fragment as a result of electron bombardment ionization.
CO2 laser interferometer for temporally and spatially resolved electron density measurements
Authors: Brannon P. J. , Gerber R. A. , Gerardo J. B.
Published: March 2003

A 10.6-μm Mach–Zehnder interferometer has been constructed to make temporally and spatially resolved measurements of electron densities in plasmas. The device uses a pyroelectric vidicon camera and video memory to record and display the two-dimensional fringe pattern and a Pockels cell to limit the pulse width of the 10.6-μm radiation. A temporal resolution of 14 ns has been demonstrated. The relative sensitivity of the device for electron density measurements is 2×1015 cm−2 (the line integral of the line-of-sight length and electron density), which corresponds to 0.1 fringe shift.
Phase-locked yttrium iron garnet magnetometer for remote measurement of small field changes in a fluctuating background
Authors: Carpenter Kenneth H. , daSilva Marcus K.
Published: March 2003

The ferromagnetic resonance frequency in small yttrium iron garnet (YIG) spheres placed in a rf filter structure is used to measure small changes in large magnetic fields in the presence of high-level random fluctuations of the background field. (Such measurements are needed for fusion plasma diagnostics.) This YIG magnetometer probe is driven by a microwave network analyzer whose working frequency is phase locked to the probe resonance, yielding an output frequency that is linearly related to the magnetic field magnitude. The YIG filter’s phase response is used to control the system frequency, allowing measurement resolutions almost two orders of magnitude better than the YIG resonance 3 dB linewidth. Noise is effectively removed by the phase lock circuitry’s low cut-off frequency and by time averaging using a frequency counter. Accuracy is essentially limited by the uncertainty in determining the constants in the linear field-frequency equation and by maintenance of constant temperature and magnetic field direction during incremental measurements.
Q-switched, mode-locked, and cavity-dumped ruby laser
Authors: Houtman H. , Meyer J. , Hilko B.
Published: March 2003

A single, coaxial spark-gap switch is used to initiate the functions of Q switching, actively mode locking, and cavity dumping of a ruby laser oscillator. These functions are shown to be easily synchronized to high precision. As a result, a single light pulse having an energy of 180 mJ and 400 ps duration, can be dumped from the cavity after only 100 ns delay with respect to the trigger pulse. Shot-to-shot jitter of ±50 ps (with respect to switch closure), and ±10% in energy is demonstrated.
All-glass vacuum-insulated liquid-nitrogen cooled CO laser
Authors: Haupt E. , Irniger V. , Pohl D. W. , Herrmann W.
Published: March 2003

An all-glass design for a vacuum-insulated liquid-nitrogen cooled CO laser is described. The outer jacket of this laser tube consists of a silvered all-glass Dewar which efficiently thermally insulates the cryogenic reservoir. The laser is operated in a pulsed mode using car ignition coils as high-voltage transformers. The laser is inexpensive, easy to operate, and reliable. Up to 260 W peak power at 0.1 ms pulse duration and 50 pulses/s was attained.
Increasing the efficiency of a multicusp ion source
Authors: Ehlers K. W. , Leung K. N.
Published: March 2003

The characteristics of a multicusp ion source are compared for two types of permanent magnets. A technique for reducing the ion loss to the regions between the line cusps is described. The effect of this magneto-electrostatic containment scheme is shown to increase the overall efficiency of the ion source.
Measurement of the spin polarization of an optically pumped ensemble of He (23S) atoms
Authors: Cheng Chu , Giberson K. W. , Harrison A. R. , Tittel F. K. , Dunning F. B. , Walters G. K.
Published: March 2003

A technique is described that enables simple, direct determination of the spin polarization of an optically pumped ensemble of He (23S) atoms. The polarization is obtained from measurements of the attenuation of the circularly polarized output of a color-center laser tuned to the 1.08 μm He (23S1→23P0) transition.
Pulsed-laser time-of-flight atom-probe field ion microscope
Authors: Tsong T. T. , McLane S. B. , Kinkus T. J.
Published: March 2003

A linear-type pulsed-laser time-of-flight atom probe has been developed. With a flight path length of ∼200 and ∼425 cm, the mass resolution is comparable to the energy focused time-of-flight atom probe of much more elaborate mechanical and electrical design. The isotopes of Mo, Xe, and W are completely separated to the roots of the mass lines. We also discuss how the mass resolution of the pulsed-laser atom probe can be further improved and where this instrument will be useful.
Framing camera tube for subnanosecond imaging applications
Authors: Kalibjian R. , Thomas S. W.
Published: March 2003

A dissector/restorer-type framing camera tube has been characterized with a Nd:YAG mode-locked laser. The three-frame format tube, referenced to the photocathode, has a 5×5-mm field of view and 0.3-ns duration frames with better than 5 lp/mm spatial resolution. A scan-rate matching technique is described that can increase the framing speed into the subpicosecond range for this type of camera tube.
Ion-extraction performance of the circular magnetic-multipole bucket ion source applied for the neutral beam injection system of the Heliotron E machine
Authors: Sano Fumimichi , Obiki Tokuhiro , Sasaki Akihiko , Iiyoshi Atsuo , Uo Koji
Published: March 2003

The ion-beam extraction performance of the 30-kV–35-A circular magnetic-multipole bucket ion source applied for the neutral beam injection system of the Heliotron E fusion machine has been investigated with special reference to ion-beam optics. By using the numerical simulation code for the cylindrical ion-extraction system, the computational beam-divergence angles have been compared with the experimental data. The experiments show that the applied three-electrode beam optics are satisfactorily stable against source-plasma variation and that the minimum beam-divergence angle is less than 1.15 deg. The obtained optimal perveance of the ion source is nearly 6.3×10−6 (A/V3/2), and the experimental optics behavior is in reasonable agreement with the numerical prediction. On the basis of the experiments, the effect of the edge angle of the first beam-forming, high-potential electrode is also discussed. The experiment suggests that the obtuse angle (∼73°) for that edge is preferable to the acute angle (∼30°).
Electron beam probe for charge neutralization studies of heavy ion beams
Authors: Shiloh J. , Lampel M. , Sah R.
Published: March 2003

The design and operation of an electron beam probe for ion beam diagnostics is described. Advantages of this method for the analysis of space-charge neutralization studies are discussed and examples of its applications to heavy ion beams are shown.
Extraction of volume-produced H− ions from a multicusp source
Authors: Leung K. N. , Ehlers K. W. , Bacal M.
Published: March 2003

H− ions formed by volume processes are extracted from a multicusp ion source. It is shown that a permanent magnet filter together with a small positive bias voltage on the plasma grid can produce a very significant reduction in electron drain as well as a sizable increase in H− ions available for extraction. A further reduction in electron current is achieved by installing a pair of ceramic magnets at the extraction aperture. The combined arrangement improves the ratio of extracted H− ion current to electron current to about unity.
New operation mode of a microchannel plate for the detection of low-energy positive ions
Authors: Koshida Nobuyoshi , Nagashima Norio
Published: March 2003

The gain characteristics of a microchannel plate (MCP) operated in the reflection mode are measured for positive ions with energies between 100 and 300 eV. Singly charged alkali ions emitted thermionically are used as the incident ions. The gain in the reflection mode is found to be higher than that in the conventional transmission mode. A preacceleration for the penetrating ions into the channels is responsible for the high gain obtainable. This result suggests the potential usefulness of a MCP operated in the reflection mode for the detection of low-energy positive ions.
Simple double diaphragm press for diamond anvil cells at low temperatures
Authors: Daniels W. B. , Ryschkewitsch M. G.
Published: March 2003

A very simple welded double diaphragm press has been constructed and tested. It is suitable for providing the forces and displacements for operation of a diamond anvil cell and requires only a small capillary connecting a helium gas pressure source and the diamond anvil cell.
High-temperature, high-pressure 10-μm absorption cell
Authors: Robinson A. M. , Haswell P. , Billing M.
Published: March 2003

An absorption cell for use with 10-μm radiation has been designed and tested. The cell is capable of operation to 400 °C and to pressures of at least 15 atm.
Versatile sample chamber for neutron scattering work at high and low temperatures
Authors: Zabel H.
Published: March 2003

A simple sample chamber for neutron scattering work is described which can be used in the temperature range from liquid He to 740 K. The design is based on a stainless-steel conical press fit utilizing the aluminum edge of the sample can as a gasket.
Simple and economic compressors for large-volume gas transport laser systems
Authors: Seguin H. J. J. , Dow J. , Seguin V. A.
Published: March 2003

Design, construction, and operational details of a simple and efficient axial flow compressor, suitable for large closed-cycle gas transport laser applications is described. These compact and high performance devices are easily assembled from standard low-cost industrially available components. Performance achieved is as good as that of commercial units, but at an order of magnitude lower cost.
Thermoelectrically regulated sample holder for Raman spectroscopy
Authors: Pézolet Michel , Boulé Bernard , Bourque Daniel
Published: March 2003

An easily built thermostated sample cell holder for Raman spectroscopy is described. The apparatus, which uses thermoelectric heat pumps as heating and cooling elements, is characterized by a fast response and a temperature stability at the sample of better than ±0.1 °C over the −20° to 100 °C temperature range. The desired temperature can be either selected manually or controlled by computer.
100-μK temperature controller
Authors: Esman R. D. , Rode D. L.
Published: March 2003

A temperature-controller system yielding 100-μK temperature stability at and above room temperature is described. The temperature controller is dc coupled and utilizes integrated-circuit temperature sensors. The thermal interface operates at ambient pressure and provides high-speed electrical and optical access suitable for use with semiconductor lasers.
Multiple mixer, cryogenic receiver for 200–350 GHz
Authors: Archer J. W.
Published: March 2003

This paper describes a new 200–350-GHz dual polarization heterodyne radiometer receiver for radio astronomy applications. The receiver incorporates four pairs of cryogenically cooled Schottky-barrier diode single-ended mixers, each pair covering a 30–40-GHz subband of the full operating band. Each mixer, with its IF amplifier, is mounted in an individual cryogenic subdewar comprising a separate vcuum chamber and a cold stage, which may be readily thermally connected to or disconnected from the main refrigerator by a novel mechanical heat switch. A dual polarization LO diplexer is mounted on a rotary table above the subdewars. For band selection, the two diplexer rf output ports may be positioned over any of the four pairs of subdewars. The SSB receiver noise temperatues achieved are less than 500 K between 200 and 240 GHz, less than 800 K between 245 and 275 GHz and 1500 K at 345 GHz.
Measurement of static magnetization using electron spin resonance
Authors: Schultz S. , Gullikson E. M.
Published: March 2003

A method is presented for measuring the dc magnetization of a sample using a conventional electron spin resonance (ESR) spectrometer. This method has the feature that the magnetization is obtained simultaneously with the ESR spectrum of the sample. However, the method may also be applied to samples not exhibiting an ESR signal.
Instrument to detect vapor nucleation of superheated drops
Authors: Apfel Robert E. , Roy S. C.
Published: March 2003

An instrument to detect the vaporization of superheated drops is described. Using this instrument, quantitative tests have been performed of the response of the superheated drop neutron detector [Nucl. Instrum. Methods 162, 603 (1979)], a tool for possible use in neutron dosimetry, area monitoring, and nuclear spectroscopy.