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Sep 1991

Volume 62, Issue 9, pp. 2063-2293

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On a new class of field integral constraints for asymmetric adjustable‐phase insertion devices

Roman Tatchyn

Rev. Sci. Instrum. 62, 2063 (1991); http://dx.doi.org/10.1063/1.1142367 (6 pages)

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Some alternative methods of tuning variable‐field transverse insertion devices that longitudinally displace the jaws of otherwise ordinary undulator structures have been recently proposed. In this article we discuss some of the off‐axis characteristics of such schemes that could limit their range of tunability and affect their possible modes of implementation on conventional storage rings. Based on the corresponding analysis, a new set of field integral constraints for facilitating the operation of such devices is derived.
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07.77.-n Atomic, molecular, and charged-particle sources and detectors
29.20.db Storage rings and colliders
29.27.Eg Beam handling; beam transport

An active vibration isolation system for inertial reference and precision measurement

Peter G. Nelson

Rev. Sci. Instrum. 62, 2069 (1991); http://dx.doi.org/10.1063/1.1142368 (7 pages) | Cited 8 times

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We describe an active low‐frequency vibration isolation system based on an earlier instrument developed at the Joint Institute for Laboratory Astrophysics (JILA). Several modifications, which have led to improved transient response, temperature stability, and a greatly reduced size, are discussed. We also comment on how the performance of the system is limited by sensor noise, mechanical resonances, and cross couplings between the different degrees of freedom.
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91.10.-v Geodesy and gravity
07.90.+c Other topics in instruments, apparatus, and components common to several branches of physics and astronomy (restricted to new topics in section 07)

High power N2 laser with a modified gas flow system and discharge geometry

Thomas Baby, T. Ramachandran, K. Sathianandan, V. P. N. Nampoori, and C. P. G. Vallabhan

Rev. Sci. Instrum. 62, 2076 (1991); http://dx.doi.org/10.1063/1.1142369 (4 pages) | Cited 3 times

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A high power N2 laser of the double‐Blumlein type having a modified gas flow system, electrode configuration, and discharge geometry with minimum inductance is described. By incorporating a triggered‐pressurized spark gap switch, arc‐free operation was achieved for a wide E/P range. The device gives a peak power in excess of 700 kW with a FWHM of 3 ns and an efficiency of 0.51%, which is remarkably high for a pulsed nitrogen laser system. The dependence of output power on parameters such as operating pressure, voltage, and repetition rate are discussed.
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42.60.By Design of specific laser systems
42.55.Lt Gas lasers including excimer and metal-vapor lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

An arrangement of two reflective photodetectors for measuring all four Stokes parameters of light

R. M. A. Azzam

Rev. Sci. Instrum. 62, 2080 (1991); http://dx.doi.org/10.1063/1.1142370 (3 pages)

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A folded‐path two‐detector photopolarimeter for measuring all four Stokes parameters of light is described. The light beam, whose state of polarization is to be measured, strikes the two (windowless and reflective) detector surfaces at oblique incidence and with noncoincident planes of incidence. After reflection from the second detector, the beam is folded back on itself by a mirror and the feedback is interrupted periodically with a light chopper. This intermittent feedback causes square‐wave modulation of the two detector outputs which provides a 4×1 current vector I. The unknown 4×1 Stokes vector S of incident light is determined by S=A−1 I, where A is a wavelength‐dependent 4×4 instrument matrix which is fixed by calibration. Based on an explicit expression for det A, all potential singularities of A are investigated and are found to be readily avoidable. Optimum parameters are also specified that make A as far from singular as possible by maximizing its determinant.
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07.60.Fs Polarimeters and ellipsometers
42.25.Ja Polarization

A dual beam total internal reflection fluorescence spectrometer for dynamic depth resolved measurements of biochemical liquid‐solid interface binding reactions in opaque solvents

Lars W. Liebmann, John A. Robinson, and Kenneth G. Mann

Rev. Sci. Instrum. 62, 2083 (1991); http://dx.doi.org/10.1063/1.1142371 (10 pages) | Cited 2 times

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The initiation of many physiologically important biochemical reactions is dependent on the binding of a molecule or molecules from solution to an appropriate solid surface such as a cell membrane. The quantitative study of dynamic interactions of molecules in solution with immobilized surfaces under physiologically relevant conditions presents a significant physical problem. Traditionally these measurements have been performed by discontinuous, nonequilibrium assays that cannot accurately model in vivo reaction mechanisms. Total internal reflection fluorescence spectroscopy (TIRFS) is an analytical technique that is based on the excitation of fluorescence by means of an exponentially decaying surface energy wave called the evanescent wave. The limited ‘‘penetration depth’’ of the evanescent wave leads to excitation of fluorescent molecules at or near the surface. This phenomena makes TIRFS uniquely qualified for the dynamic fluorescence study of liquid‐solid interface binding reactions. The instrument described here permits the powerful technique of TIRFS to be used by biomedical researchers in their investigation of biochemical interface reactions. The fully automated, menu driven instrument allows the real time dynamic measurement of binding of fluorescent‐labeled molecules in solution at physiologically relevant concentrations to appropriate immobilized surfaces.
The novel design of the total internal reflection element enables the study of binding from essentially opaque and highly scattering solutions such as whole blood. Measurements may be performed under static, stirred, or flow conditions. The presently described TIRFS instrument is capable of tracking a binding reaction with evanescent fields established by two identical reflecting light beams with different reflection angles. This instrumental feature allows the dynamic measurement not only of the primary binding event but also of fluctuations in the distance between the optical interface and the point of signal generation. Data from experiments involving fluorescently labeled molecules binding to cell monolayers as well as binding experiments performed in whole blood are shown to verify the instrument performance. Due to its extraordinary capabilities and its user friendly design, the developed TIRFS instrument opens up a large number of relevant but previously unmeasurable experimental systems for investigation.
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07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
87.16.-b Subcellular structure and processes
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
07.77.-n Atomic, molecular, and charged-particle sources and detectors
37.20.+j Atomic and molecular beam sources and techniques

Analysis of slit function errors in single‐shot coherent anti‐Stokes Raman spectroscopy (CARS) in practical combustors

Shawn P. Heneghan and Marlin D. Vangsness

Rev. Sci. Instrum. 62, 2093 (1991); http://dx.doi.org/10.1063/1.1142372 (7 pages) | Cited 3 times

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The temperature determined by a single‐shot coherent anti‐Stokes Raman spectroscopy (CARS) system is directly related to the half width at half maximum of the instrument slit function. Therefore, an accurate knowledge of the instrument slit function is necessary to determine temperature with CARS. However, in turbulent systems, the input slits of the spectrometer may be removed in order to guarantee signal throughput and establish the necessary dynamic range. In this case, the physical input slits of the spectrometer are replaced with apparent slits created by focussing the input beams near the entrance plane of the spectrometer. The slit function will then depend on the physical relationship among all of the optical components, the probe volume, and the dispersive performance of the spectrometer and detector, as well as the optical path through density and temperature gradients which may not be invariant in a turbulent system. The presence of high temperatures and turbulence levels can effect the size of the CARS signal origin and the optical path, and as a result, the slit function is not invariant. Ignoring these changes can result in large root mean square temperatures (decreased precision) as well as mean temperature errors. The variability of the slit width can be accounted for on a shot‐to‐shot basis by using a two parameter (HWHM of the slit function and temperature) fitting routine. For temperatures greater than 1200 K there is convergence on a best curve implying both a temperature and a slit width. This method can be used alone or in concert with various weighting schemes to improve the precision. There are two major advantages gained by allowing the slit function to vary in a CARS system: (a) it allows an increase in the precision; (b) it allows temperatures to be calculated without the assumption that the slit function does not change with temperature or turbulence or position within the flame. In fact, it allows the temperature to be determined with almost no previous knowledge of the slit function except the general shape. These two advantages combine to significantly simplify the study of turbulent combusting systems with CARS and to improve the precision, both point‐to‐point and shot‐to‐shot, of CARS.
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42.65.Dr Stimulated Raman scattering; CARS
42.65.Es Stimulated Brillouin and Rayleigh scattering
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
82.33.Vx Reactions in flames, combustion, and explosions

Multichannel time‐correlated single photon counting: Spectroscopy and time‐gated imaging using a resistive anode photomultiplier tube

Scott H. Courtney and William L. Wilson

Rev. Sci. Instrum. 62, 2100 (1991); http://dx.doi.org/10.1063/1.1142373 (5 pages) | Cited 13 times

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A multichannel single photon counting detection system for steady state, time‐resolved luminescence spectra, time‐gated imaging, or time‐gated Raman is described. This system, which has approximately 80 ps time resolution, is based on a microchannel plate photomultiplier with a position‐sensitive anode (Mepsicron). This detector can operate at very low light levels with excitation wavelengths from 200 nm to the near infrared. For time‐resolved luminescence applications, the system simultaneously collects 1024 decays of up to 1024 spectral channels. The measured time dispersion for spectral bandwidths greater than 100 nm are shown to be negligible.
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07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
07.60.Rd Visible and ultraviolet spectrometers
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors

CO2 gas sensor using acousto‐optic Bragg diffraction in As2Se3 glass

Mitsunori Saito and Mitsunobu Miyagi

Rev. Sci. Instrum. 62, 2105 (1991); http://dx.doi.org/10.1063/1.1142374 (4 pages) | Cited 1 time

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An acousto‐optic (AO) element made of As2Se3 glass was used for spectroscopic gas sensing. With the AO element, desired wavelengths in the infrared can be monitored by simply switching the oscillation frequency of the ultrasonic transducer. The concentration of the CO2 gas was measured by using the absorption band at 4.3 μm wavelength. To avoid measurement error due to the fluctuation in the sensing system, a probe light of 4.3 μm and a reference light of 4.7 μm were measured alternatively by switching the acoustic frequency between 50 and 54 MHz. It has been demonstrated in a preliminary experiment that the AO element is a promising device for constructing a fast, compact, and inexpensive measurement system for monitoring pollutants.
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07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
07.60.Rd Visible and ultraviolet spectrometers
78.20.hb Piezo-optical, elasto-optical, acousto-optical, and photoelastic effects

Water‐cooled quasi‐doubly bent crystal monochromator for Compton scattering experiments

Hiroshi Kawata, Masato Sato, Toshiaki Iwazumi, Masami Ando, Nobuhiko Sakai, Masahisa Ito, Yoshikazu Tanaka, Nobuhiro Shiotani, Fumitake Itoh, Hiroshi Sakurai, Yoshiharu Sakurai, Yosiyuki Watanabe, and Susumu Nanao

Rev. Sci. Instrum. 62, 2109 (1991); http://dx.doi.org/10.1063/1.1142375 (6 pages) | Cited 12 times

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Commissioning and performance of a water‐cooled quasi doubly bent crystal monochromator for Compton scattering experiments are described. The monochromator consists of an array of twenty singly bent crystals. Each crystal is half immersed in liquid Ga‐ln alloy contained in a water‐cooled holder. This is necessary because the monochromator must be able to withstand heat load of 4 kW from synchrotron radiation from an ellipsoid multipole wiggler at the 6.5 GeV accumulation ring. The alignment procedure for twenty singly bent crystals is described in detail. Its performance is as follows; the focused beam size of 60 keV x rays is about 3 mm (vertical) and 8 mm (horizontal). The flux is 6×1012 photons/s at stored currents of 30 mA and the energy resolution is 88 eV for 60 keV x rays. Heating of various adjusting mechanisms by Compton scattered x rays from both the absorber used to suppress low energy x rays and the monochromator crystals is found to be a very serious problem for designing a high energy x‐ray beamline.
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07.60.Rd Visible and ultraviolet spectrometers
78.70.Ck X-ray scattering

Kilohertz‐range flash x‐ray generator utilizing a triode in conjunction with an extremely hot cathode

E. Sato, A. Shikoda, S. Kimura, M. Sagae, H. Isobe, K. Takahashi, Y. Tamakawa, T. Yanagisawa, K. Honda, and Y. Yokota

Rev. Sci. Instrum. 62, 2115 (1991); http://dx.doi.org/10.1063/1.1142376 (6 pages) | Cited 9 times

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The construction and the fundamental studies of a kilohertz‐range flash x‐ray generator having a triode in conjunction with an extremely hot cathode are described. This generator consisted of the following components: a constant‐high voltage power supply, an energy storage condenser of 100 nF, a constant high‐voltage power supply for regulating an initial grid voltage of −1.6 kV, a grid pulser, and an x‐ray tube. The x‐ray tube was of an enclosed‐triode type and consisted of the following major parts: an anode rod made of copper, a plane anode tip (target) made of tungsten, a focusing electrode made of iron, a hot cathode (filament) made of tungsten, a grid made from tungsten wire, and a glass tube body. The energy storage condenser was charged from 50 to 70 kV, and the electric charges in the condenser were discharged repetitively to the x‐ray tube by the grid electrode driven by the grid pulser. The temperature of the filament was about 2000 K, and the cathode current was primarily controlled by the grid voltage and its value was less than 1.2 A. The pulse widths were about 1 μs and the maximum repetitive frequency was about 2.0 kHz. The x‐ray intensity was 19.7 nC/kg at 0.5 m per pulse with a peak grid voltage of 1.0 kV and a condenser charged voltage of 70 kV.
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07.85.-m X- and γ-ray instruments
84.47.+w Vacuum tubes
84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables

Development of a quadrupole mass spectrometer using the second stable zone in Mathieu’s stability diagram

Seiji Hiroki, Tetsuya Abe, and Yoshio Murakami

Rev. Sci. Instrum. 62, 2121 (1991); http://dx.doi.org/10.1063/1.1142377 (4 pages) | Cited 10 times

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A quadrupole mass spectrometer (QMS) utilizing the second stable zone in Mathieu’s stability diagram was developed. The system performance was experimentally compared with the conventional QMS using the first stable zone. The peak shapes obtained were sharper and the tail components arising from adjacent peaks were less than those of the conventional QMS, although the analyzable range was limited to lower mass and the attenuation in sensitivity was about 1/50. This improved QMS is usable in detecting very small peaks adjoining large ones.
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07.75.+h Mass spectrometers

An electron‐impact ionization time‐of‐flight mass spectrometer using a simple high‐voltage square pulse generator

Kwang Woo Jung, Sung Seen Choi, and Kyung‐Hoon Jung

Rev. Sci. Instrum. 62, 2125 (1991); http://dx.doi.org/10.1063/1.1142378 (6 pages) | Cited 9 times

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A versatile electron‐impact time‐of‐flight mass spectrometer (EI‐TOFMS) in a pulsed molecular beam has been constructed. The instrument contains a fast rise time, square pulse generator, biased at high voltage, which simplifies the implementation of EI‐TOFMS. Power field effect transistors are used as the active switching element, which afford compact size and simplified circuit construction. The effect of the shape of the repelling pulse on the flight time and space focusing condition is estimated by numerical calculation. Preliminary test results are provided for pulsed molecular beams of ammonia and hydrogen iodide.
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07.75.+h Mass spectrometers
36.40.-c Atomic and molecular clusters
82.33.Vx Reactions in flames, combustion, and explosions

A quadratic potential time‐of‐flight mass spectrometer for use with slow positron ionization sources and other large‐volume ion sources

L. D. Hulett, D. L. Donohue, and T. A. Lewis

Rev. Sci. Instrum. 62, 2131 (1991); http://dx.doi.org/10.1063/1.1142327 (7 pages) | Cited 16 times

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A time‐of‐flight spectrometer has been specially designed for measuring the masses of ions produced by low‐energy positrons interacting with organic molecules in a Penning trap. To make the flight times insensitive to the starting positions of the ions in the trap, acceleration was done using a potential that varied as the square of the distance of the ion from the detector. The containment of the positrons in the Penning trap for extended time periods effected very long collision paths between the positrons and the molecules. The entire length of the Penning trap source could be sampled. These features produced high sensitivity, enabling the measurement of ionization processes with small cross sections. The spectrometer is useful for mass spectrometry of ions produced by processes other than positron interaction. Both large and small volume sources can be accommodated.
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07.75.+h Mass spectrometers
29.25.Lg Ion sources: polarized
29.25.Ni Ion sources: positive and negative
52.80.Sm Magnetoactive discharges (e.g., Penning discharges)

Spectroscopic plasma tomography with multiple photocollector arrays

Satoshi Sugimoto and Seiich Goto

Rev. Sci. Instrum. 62, 2138 (1991); http://dx.doi.org/10.1063/1.1142328 (4 pages) | Cited 4 times

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A spectroscopic plasma tomography measurement system has been developed and operated on a field‐reversed configuration (FRC) plasma machine with the use of five photocollector arrays. Each photocollector array that is located azimuthally around the plasma column consists of ten optical fibers and a pinhole. Two‐dimensional (2D) and time‐resolved visible emission profiles can be reconstructed numerically from the fifty‐channel projection data. The use of five multichannel visible monochromators makes it possible to obtain a result that has explicit physical meanings. A computer simulation has been performed to demonstrate the potential to reconstruct the 2D profile without the assumptions about plasma rotation or symmetry. The first experimental result for visible bremsstrahlung emission profiles of the FRC plasma is presented.
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52.70.-m Plasma diagnostic techniques and instrumentation
42.30.Wb Image reconstruction; tomography

Production of a 95% proton yield beam in a semicylindrical plasma generator

Kazuhiro Watanabe, Masanori Araki, Masayuki Dairaku, Hiroshi Horiike, Yoshihiro Ohara, Yoshikazu Okumura, Jérôme Paméla, Shigeru Tanaka, and Kenji Yokoyama

Rev. Sci. Instrum. 62, 2142 (1991); http://dx.doi.org/10.1063/1.1142329 (4 pages) | Cited 3 times

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A high proton yield beam was produced in a semicylindrical multicusp plasma generator. The dimension of the cylinder is 34 cm in diameter and 129 cm in length, and the beam extraction area is 8 cm in width and 120 cm in length. A strongly linked magnetic field configuration was utilized to confine the primary electrons in the cylinder and prevent them from flowing into the beam extraction region. As a temporary test hydrogen ion beams were extracted from the central region of the plasma generator. Ion species in the beam were measured by a Doppler‐shifted spectroscopy of Balmer‐alpha light and found to be 95% at a beam current density of 175 mA/cm2 at the filling pressure of 0.4 Pa.
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52.50.Dg Plasma sources
07.77.-n Atomic, molecular, and charged-particle sources and detectors
52.70.Kz Optical (ultraviolet, visible, infrared) measurements

A method to measure poloidal field coil irregularities in toroidal plasma devices

R. J. La Haye and J. T. Scoville

Rev. Sci. Instrum. 62, 2146 (1991); http://dx.doi.org/10.1063/1.1142330 (8 pages) | Cited 23 times

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A ring of accurately placed and matched printed circuit coils is placed at the center of the DIII‐D tokamak vacuum vessel, aligned magnetically with the toroidal field and used to measure the nonaxisymmetric magnetic field of each of the 18 poloidal field coils. [Toroidal and poloidal variations can be of mode n and m, respectively, with helical variations of form cos(nϕ−mθ).] From the error fields, it is computed that the most irregular poloidal field coil is one of the outer vertical field coils having a shift of 1.9 ±0.2 cm (compared to a diameter of 482 cm), and having an ellipticity 1.0027. All the 18 poloidal field coils together make a resonant, helical, radial error field for m=2, n=1 of about 1.4 × 10−4 of the toroidal field.
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52.55.Fa Tokamaks, spherical tokamaks

Compact supersonic molecular beam source with a liquid nitrogen trap

Hidehiko Nonaka, Takashi Shimizu, and Kazuo Arai

Rev. Sci. Instrum. 62, 2154 (1991); http://dx.doi.org/10.1063/1.1142331 (5 pages) | Cited 3 times

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A compact supersonic molecular beam source was developed that has a liquid nitrogen trap to cryogenically pump the gas and is small enough in size to install in conventional molecular beam epitaxy (MBE) systems. With the source, well‐collimated molecular beams of N2O and NO2 whose flux densities are ∼1016 molecules cm−2 s−1 are generated. The effectiveness of the source was proved in the preparation of oxide superconducting thin films by MBE with an NO2 beam where as‐grown superconducting films were obtained in high vacuum of ≤10−5 Pa.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment

A low temperature NMR probe for use in a dilution refrigerator

P. L. Kuhns, S.‐H. Lee, C. Coretsopoulos, P. C. Hammel, O. Gonen, and J. S. Waugh

Rev. Sci. Instrum. 62, 2159 (1991); http://dx.doi.org/10.1063/1.1142332 (4 pages) | Cited 5 times

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We report an NMR probe that we use in ultra low temperature experiments in a top‐loading dilution refrigerator. The probe is thermally anchored to the 1.2 K pumped 4He pot and is thermally isolated from the sample located inside a Kel‐F cup containing liquid 3He. The probe is adapted from a standard double resonance probe, using air trimmer capacitors, a λ/4 cable, a homemade saddle coil, and metal film resistors. The double resonance design breaks the probe’s tuning ranges into two bands. The high frequency band tunes from 100 to 150 MHz covering all the nuclei with large gyromagnetic ratios, 3H, 19F, 1H, 3He. The low frequency band tunes for 17 to 54 MHz covering all nuclei with gyromagnetic ratios between 133Cs and 119Sn. The air trimmer capacitors have an open structure that allows efficient pumping and the metal film resistors are used to reduce the Q of the probe. This probe has been successfully used for a wide range of nuclei including 1H, 19F, 3He, 119Sn, 117Sn, 115Sn, 11B, 13C, 29Si, 27Al, and 2H.
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07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment

Semiautomated analysis of clay samples

Luciano da F. Costa, Xiaoling Leng, Mark B. Sandler, and Peter Smart

Rev. Sci. Instrum. 62, 2163 (1991); http://dx.doi.org/10.1063/1.1142333 (4 pages) | Cited 3 times

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Important information about physical characteristics of clays can be inferred from the distribution of the orientations of straight lines in photographs of cross sections of its samples. This article describes the development of a semiautomated system for clay analysis that is based on the application of computer vision techniques. Due to the inherent complexity of these techniques, two strategies have been used in order to reduce the execution time: an effective technique, the binary Hough transform, is applied for detection of straight lines and the transputer is used to enhance the system processing power. The article includes the characterization of the clay analysis application, the description of the binary Hough transform for detection of straight line segments, the presentation of the semiautomated system, and a complete illustrative example.
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07.05.-t Computers in experimental physics
42.30.Wb Image reconstruction; tomography
91.60.-x Physical properties of rocks and minerals

Scanning probe tips formed by focused ion beams

M. J. Vasile, D. A. Grigg, J. E. Griffith, E. A. Fitzgerald, and P. E. Russell

Rev. Sci. Instrum. 62, 2167 (1991); http://dx.doi.org/10.1063/1.1142334 (5 pages) | Cited 30 times

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Probe tips for scanning tunneling microscopy have been sharpened using focused ion beam milling. Reproducible tips were formed on polycrystalline W and Pt‐Ir shanks, but this technique is not limited to these materials. The tips were found to have cone angles of 12±3° and radii of curvature as sharp as 4 nm. Focused ion beam machining allows precise control of the final shape of the tips which is important in metrology measurements of various nanostructure devices.
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07.78.+s Electron, positron, and ion microscopes; electron diffractometers
41.75.Ak Positive-ion beams
41.75.Cn Negative-ion beams
07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination

Apparatus for adsorption studies

M. Rocca, U. Valbusa, A. Gussoni, G. Maloberti, and L. Racca

Rev. Sci. Instrum. 62, 2172 (1991); http://dx.doi.org/10.1063/1.1142335 (5 pages) | Cited 52 times

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In this paper a UHV apparatus for studying adsorption of gases on surfaces will be described. The system is specifically designed for measuring the sticking coefficient of a molecule on the surface and its dependence on energy and angle of incidence. The method is based on the use of an electron energy loss spectrometer which detects the amount of the adsorbed species as a function of the exposure of the surface to a supersonic nozzle beam which deposits the molecular species at different energies and angles of incidence. Measurements of the sticking probability of O2 on Ag(001) are presented showing the capability of the method.
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07.30.Hd Vacuum testing methods; leak detectors
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

An ultrahigh vacuum single crystal adsorption microcalorimeter

C. E. Borroni‐Bird and D. A. King

Rev. Sci. Instrum. 62, 2177 (1991); http://dx.doi.org/10.1063/1.1142525 (9 pages) | Cited 65 times

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The design of an ultrahigh vacuum microcalorimeter enabling calorimetric heats of adsorption to be obtained on single crystal surfaces as a detailed function of coverage is discussed. The system comprises a pulsed supersonic molecular beam source, an ultrathin metal single crystal, and remote infrared temperature sensing. Sticking probabilities and coverages are determined pulsewise by the King and Wells method, and heat capacity calibrations are conducted in situ by laser beam pulsing. Results for CO and O2 on Ni{110} demonstrate excellent sensitivity to adsorption of ∼10−13 moles of gas (∼0.01 monolayer). The heat capacity of the calorimeter is 4.2 μJ K−1.
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07.20.Fw Calorimeters
68.43.-h Chemisorption/physisorption: adsorbates on surfaces

A high‐pressure volumetric gas adsorption system

F. W. Giacobbe

Rev. Sci. Instrum. 62, 2186 (1991); http://dx.doi.org/10.1063/1.1142336 (7 pages) | Cited 2 times

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A unique, all‐metal, volumetric gas adsorption system has been described. This device was capable of facilitating precise and semiautomatic measurements which could be used to produce complete adsorption isotherms. Isotherm temperatures could be controlled and maintained at the boiling point of liquid nitrogen, argon, and oxygen. In addition, relatively high‐pressure adsorption isotherms could be measured due to the all‐metal construction of the adsorption system.  
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07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

A ‘‘Quad‐Disc’’ static pressure probe for measurement in adverse atmospheres: With a comparative review of static pressure probe designs

Randall T. Nishiyama and Alfred J. Bedard

Rev. Sci. Instrum. 62, 2193 (1991); http://dx.doi.org/10.1063/1.1142337 (12 pages) | Cited 16 times

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There are many areas of need for accurate measurements of atmospheric static pressure. These include observations of surface meteorology, airport altimeter settings, pressure distributions around buildings, moving measurement platforms, as well as basic measurements of fluctuating pressures in turbulence. Most of these observations require long‐term observations in adverse environments (e.g., rain, dust, or snow). Currently, many pressure measurements are made, of necessity, within buildings, thus involving potential errors of several millibars in mean pressure during moderate winds, accompanied by large fluctuating pressures induced by the structure. In response to these needs we designed a ‘‘Quad‐Disc’’ pressure probe for continuous, outdoor monitoring purposes which is inherently weather protected. This Quad‐Disc probe has the desirable features of omnidirectional response and small error in pitch. A review of past static pressure probes contrasts design approaches and capabilities.
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07.90.+c Other topics in instruments, apparatus, and components common to several branches of physics and astronomy (restricted to new topics in section 07)
89.60.-k Environmental studies
92.90.+x Other topics in hydrospheric and atmospheric geophysics (restricted to new topics in section 92)

Aeroacoustic flow sensor

P. Shakkottai, E. Y. Kwack, and L. H. Back

Rev. Sci. Instrum. 62, 2205 (1991); http://dx.doi.org/10.1063/1.1142338 (8 pages) | Cited 1 time

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A theoretical analysis of standing waves in a pipe with flow was conducted aimed toward the development of a flowmeter based on a measurement of phase difference between two points on the circumference of a pipe separated axially by an integral multiple of half sound wavelength. Effects of nonzero Mach number, variable ratios of upstream and downstream running waves, choice of location of the sensing pressure taps, and the incorrect spacings were examined numerically. Calculations were also made for steam flow where the maximum Mach number is much smaller than in cold air flows. For an industrial application where steam flow velocities are below 50 m/s, a very accurate sensor is shown to be possible. Experimental data were obtained by using an active aeroacoustic source over the range of 50 m/s to zero in an air flow. Experimental phase plots obtained from several coast‐down tests have been compared with analytical results. The agreement with theory is excellent when the spacings are near Nλ/2 and the sensing locations are near the pressure antinodes. Otherwise, some zero shifts are introduced. Theory predicts that for steam flow much better results can be expected because the maximum Mach number is much smaller. Effects due to the (1−M2) factor would be imperceptible for steam flow.
Show PACS
47.80.-v Instrumentation and measurement methods in fluid dynamics
47.60.-i Flow phenomena in quasi-one-dimensional systems
43.58.+z Acoustical measurements and instrumentation
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