bluuebunny/crossref_metadata_2025 huggingface dataset:
Straight Edge Profile Analysis by the Diffractographic Method with Application to Razor Blades
Authors: Hageniers O. L. , Pryor T. R. , Pastorius W. J. , North W. P. T.
Published: February 2004

Presented is an application of the recently described diffractographic method to razor blade edge profile analysis. Using the technique, the whole edge profile may effectively be viewed at considerably higher magnification than is obtainable with conventional contour projectors. In addition, the profile may be electro-optically scanned to yield apparently reliable magnifications in excess of 50 000×. The easily automated nature of the scan process is an additional advantage.
An Acoustic Device for Determining the Isotopic Ratio of a 3He–4He Gas
Authors: Fraser J. C.
Published: February 2004

An acoustic device is described which measures the 3He concentration of a 3He–4He gas mixture. The device was designed to provide an inexpensive system to continuously monitor the operation of a 3He–4He dilution refrigerator. The isotopic fraction may be easily measured to a precision of 1%.
A Proton Magnetic Field Controller
Authors: La Force Richard Conley , La Force Gunilla , Hansen Christopher R.
Published: February 2004

We have designed, constructed, and operated a magnetic field controller that locks the field to a proton nuclear magnetic resonance signal. The frequency of the proton spectrometer is, in turn, locked to a frequency swept synthesizer. The controller operates over ±1000 Oe centered at 3000 Oe. The long term stability is 3×10−3 Oe.
An Experimental Method for Interdigital Surface Wave Transducer Weighting
Authors: Haydl William H.
Published: February 2004

A simple experimental method to change the finger overlap and thus the frequency response of interdigital transducers is described. The method allows many changes to be made on the same transducer and should prove of value in the development of surface wave devices.
High Voltage Pulse Amplifier Drives Capacitive Loads with Short Rise Times
Authors: VAN DER Veeke A. A.
Published: February 2004

A simple low power complementary cascade amplifier is described which can deliver relatively high voltage pulses to capacitive loads. The pulse amplitude is about 170 V, while the rise times are between 15 and 60 nsec for capacitive loads between 20 and 300 pF.
Alloys for Fabricating Apertures for Cu Kα X-Ray Experiments
Authors: Hallock Robert B.
Published: February 2004

Certain readily available alloys, composed primarily of bismuth, have been found well suited for the fabrication of apertures and slits used to define beams of Cu Kα x rays. The primary advantage of these alloys is the ease with which they can be cast and then machined to relatively high tolerances.
Waveform-Independent Lock-In Detection
Authors: Geist Jon
Published: February 2004

A modification of the commonly used lock-in detection technique is proposed. This technique produces an output signal that is independent of the waveform of the input signal.
An Inexpensive Electronically Controlled Constant Rate Addition Funnel
Authors: Engel Paul S.
Published: February 2004

The construction of an inexpensive electronically controlled constant rate addition funnel is described. The device is capable of slowly adding liquid reagents to a chemical reaction and features both variable pulse intervals and variable pulse width.
A Bellows Seal Superfluid Valve
Authors: Hallock Robert B.
Published: February 2004

A superfluid-tight valve that utilizes a bellows is described. Features of the valve include a nonrotating seal and ready interchangeability of parts.
Cleaning and Activation of Beryllium-Copper Electron Multiplier Dynodes
Authors: Pongratz Morris B.
Published: February 2004

The cleaning and activation procedure followed in preparing beryllium-copper dynodes for electron multipliers used in sounding rocket experiments to detect auroral electrons is described.
Fluorine Pressure Change Monitor for a Reacting System
Authors: Suchard Steven N. , Bergerson Lee D.
Published: February 2004

Recent experimental results on the performance of a pulsed HF chemical laser have indicated that the presence of HF in the chemical reactants prior to laser initiation degrades the laser performance. In order to monitor the amount of HF produced when the chemical reactants are mixed, a device has been developed that measures the change in concentration of one of the reactants. This device, which relies on the absorption of light by molecular F2, has been shown to have an accuracy of better than 5% in the measurement of the F2 pressure.
Temperature Controller for Dilution Refrigerators
Authors: Burgess A. E. , Crooks M. J.
Published: February 2004

An electronic analog device for automatically controlling the mixing chamber temperature of a dilution refrigerator is described. A self-inductance magnetic thermometer is used as the temperature sensing element. Using this device we were able to hold the mixing chamber temperature changes to less than 0.1 mK for periods of up to 12 h in the temperature range between 0.4 and 0.1 K.
A Capacitance Meter for Bilayer Membrane Studies
Authors: Wobschall Darold
Published: February 2004

A meter which features direct readout of the capacitance of artificial lipid bilayer membranes is described. It is basically an ac ohmmeter that has been designed to minimize the commonly encountered series (solution) and input resistance errors. An accuracy of about 3% can be achieved for typical membrane capacitances of 10−3−10−1 μF.
Cementing Teflon at Low Temperatures
Authors: Reichert Jonathan F.
Published: February 2004

Ordinary rubber cement has been found to make a strong and reliable low temperature bond between Teflon and a wide variety of materials.
Thermometric Properties of Carbon-Impregnated Porous Glass at Low Temperatures
Authors: Lawless W. N.
Published: February 2004

Samples (4.8×1.6×1.0 mm) were cut from a plate of carbon-impregnated porous glass, encapsulated in He-filled Pt cans as two-lead devices, and their thermometric properties measured from 2 to 400 K. This material has a large sensitivity (R77/R300≅2.0, R4.2/R300≅130) combined with a relatively small resistivity (R4.2≃2100 Ω, R77≃34 Ω, R300≃17 Ω, for the samples' size), and d lnR/d lnT is smooth and monotonic over this temperature range. Repeatability of the two-lead device is ≃±0.8 mK at 4.2 K and <±60 mK at 77 K, and no evidence of isothermal aging was observed. The magnetoresistance was measured at 4.2 K in fields up to 30 kG and found to be approximately twice as large as for carbon radio resistors at 4.2 K. Curve-fitting studies were made over increasingly larger temperature intervals (2–5, 2–10,…, 2–200 K) based on the equation log R=A+BT−P, and it was found that in each interval the R−T data could be fitted to better than 1% of the upper temperature. An interesting scaling relation was found between the R−T curves of the units, such that at each temperature, Ri=bRjm for the ith and jth units, where b and m are constants. This scaling could permit a two-point calibration transfer. It is postulated that the broad-range thermometric properties of this material derive from the high-purity carbon filaments deposited in the ∼40 Å pore-size porous glass.
Sweep Generator for MOS Analysis
Authors: Munro Philip C. , Thompson H. W.
Published: February 2004

A sweep generator is described which provides an output voltage of triangular wave shape variable in frequency from 0–1.6 Hz, variable in peak-to-peak amplitude from 0–100 V, and variable in offset from zero by dc voltages up to ±150 V. The waveform is stable and linear, and the sweep voltage can be held at any point on the waveform for moderate periods of time (minutes) without significant change in voltage, and can be held indefinitely at either peak value of the waveform.
Secondary-Ion Collection System for an Ion Microprobe Analyzer of High Mass Resolution
Authors: Krohn V. E. , Ringo G. R.
Published: February 2004

An optical system by which about 10% of the secondary ions produced by an ion microprobe are collected into the acceptance phase space of a mass spectrometer, of mass resolution over 10 000, is described. The crucial feature is that the specimen stage is divided into sections of different potential, so that the secondaries can be steered when they are at low velocities.
A Technique for Measuring Equilibrium Thermodynamic States of Liquid Metals at High Temperatures and Pressures
Authors: Henry K. W. , Stephens D. R. , Steinberg D. J. , Royce E. B.
Published: February 2004

This paper presents a method for overcoming temperature and pressure limitations inherent in conventional techniques for measuring equilibrium thermodynamic data. The method can be applied to conducting materials that can be resistively heated and that do not dissociate in the liquid phase; and it is thus particularly suitable for investigating pure liquid-metal thermodynamic data. The technique has been applied extensively to lead at temperatures exceeding 5000 K and at pressures up to 2 kilobars. A cylindrical material specimen 1 mm in diameter and 25 mm long is interposed between two current leads and mounted axially concentric with a high-pressure cell. After the cell is pressurized with helium, a current pulse from the overdamped discharge of a high-voltage capacitor bank heats the wire at such a rate that its expansion is nearly isobaric. The energy deposited in a central segment of the sample is computed by integrating the product of the current flowing in the segment with the resistive voltage developed across it. With these data, sample resistance can also be calculated during a major portion of the time that current flows. Because mounting constraints limit sample expansion to the radial dimension, the equilibrium volume is calculated from the expanded diameter, which is measured by means of pulsed x-radiography.
An Elevated Temperature Torsional Fatigue Testing Fixture
Authors: Socie Darrell F. , Antolovich Stephen D. , Chanani Govind R.
Published: February 2004

A simple fixture that can be used with any closed-loop tensile testing system for torsional cyclic testing is described. This fixture was successfully used for low cycle fatigue and crack growth rate studies of high-strength steels both at ambient and elevated temperatures. The unique design of this fixture is that by using the output of the torque cell as the feedback to the servocontroller of the hydraulic tensile testing machine, the applied torque remains independent of all machine variables and the tests can be programmed to follow any torque/time profile.
Continuous Measurement of Internal Friction and Modulus with a Regenerative Feedback Loop and Composite Oscillator
Authors: Gerk A. P.
Published: February 2004

Continuous measurement of the internal friction and modulus defect in covalent crystals has been obtained by using a regenerative feedback loop in conjunction with the Marx composite oscillator technique. This system was designed specifically for the rapid measurement of strain-dependent internal friction at elevated temperatures; however, it can readily be used to measure automatically the internal friction in a variety of systems.
Intensified Ultraviolet Analyzing Lamp for Flash Photolysis
Authors: Taylor W. B. , LeBlanc J. C. , Whillans D. W. , Herbert M. A. , Johns H. E.
Published: February 2004

An intensifier is described which increases the light level of an Osram 150 W xenon lamp by a factor of up to 30 at 350 nm, and holds it constant to 0.02% of the brightened level for 10 msec. Control for longer times is possible. This precision of control is possible only when the light level seen by a photomultiplier is used to regulate the intensified level. If two photomultipliers are used, one to observe the transient absorption signals and the other to control the light level, then the light level can be held constant to about 0.1%. This limitation is not due to the intensifier circuit, but to the difficulty of optically matching two beams and two photomultipliers.
Measurement of the Dielectric Constant and Loss Tangent of Multilayer Specimen and Its Application
Authors: Kakimoto A. , Sugiura M.
Published: February 2004

This paper describes a measuring technique for the dielectric constant and loss tangent of multilayer specimens at above 1 MHz by the apparatus devised for the varying gap immersion method. The method permits the measurement of a dielectric film formed on a substrate. Specimens that cannot be immersed directly in a liquid can be placed in a pouch. Since the method does not require conventional micrometer measurements of thickness of the specimen, the substrate, and the pouch, it improves the accuracy of the measurements. By this method, a whole measurement of a specimen can be done in several minutes with an accuracy of 0.5% and 5% for the dielectric constant and the loss tangent, respectively, of a low-loss specimen of polymeric film several hundred microns thick. The thickness of the specimen can also be calculated from the measured data to within 1 μ.
Operation of a Grid-Shuttered Image Converter Tube in the Picosecond Region
Authors: Schelev M. Ya. , Richardson M. C. , Alcock A. J.
Published: February 2004

Experiments have been carried out to investigate the performance of a standard, commercial, image converter tube (RCA C73435) in the picosecond region. Using a multikilovolt subnanosecond-rise time pulse generator, switched by a laser-triggered spark gap, to generate the deflection pulses, streak velocities of 1.6×1010 cm/sec and a streak-limited resolution of <5 psec have been obtained. Photocathode saturation and space charge effects are avoided with the use of low cathode currents, and, in order that photographic records can be obtained on high-speed film, a high-gain (106), four-stage magnetically focused image intensifier (EMI 9694) is optically coupled to the screen of the image converter tube. The over-all response time of the camera is also dependent on the transit time spread of the photoelectrons between the cathode and the screen and this is reduced by the application of accelerating voltages of 2500 V to the ICT grid. Evaluation of the camera system has been undertaken with the 1.06 μ fundamental output of a mode-locked neodymium glass laser. Mode-locked pulses of ∼6 psec duration were resolved.
Prequench Losses in H(2S) Cross Section Measurements
Authors: Wooten J. W.
Published: February 2004

A calculation of the fraction of incoming H(2S) atoms that decay to the ground state due to the fringing fields near a quench capacitor is done for several quench geometries. Under some possible experimental conditions, the prequench losses can be appreciable and experiments should be designed to avoid these conditions or correct for them.
Modified Magneto-Optic Hysteresigraph
Authors: Horne D. E. , Sawatzky E.
Published: February 2004

A previously described apparatus for the direct recording of Faraday rotation and magnetic hysteresis has been modified to improve the magneto-optic rotation sensitivity by about a factor of 10 compared with the original equipment. Kerr and in-plane Faraday rotation capability has been added and the maximum available field strength has been doubled.
A Simple Bakeable Hollow Cathode Device for the Direct Study of Plasma Constituents
Authors: Märk T. D. , Lindinger W. , Howorka F. , Egger F. , Varney R. N. , Pahl M.
Published: February 2004

The unique features of construction of a hollow cathode discharge apparatus are described. The device includes a highly important exit aperture that also serves as a Langmuir probe for exploring the negative glow plasma.
Q-Switched CO2 Lasers with Variable Pulse Delay
Authors: Burak I. , Gamss L. A. , Ronn A. M. , Szöke A.
Published: February 2004

Acknowledgments should have been made to the donors of the Petroleum Research Fund, Administered by the American Chemical Society, for partial support of this research.
Double Modulation Method for Hall Effect Measurements on Photoconducting Materials
Authors: Eisele I. , Kevan L.
Published: February 2004

A new double modulation method for photo-Hall mobility measurements on high impedance photoconductors is described. The magnetic field is modulated by rotating the sample in the field and the density of charge carriers is modulated by chopping the light beam which induces photoconductivity. The Hall signal is detected at the sum frequency of the two modulations and a clear distinction in phase and frequency between the Hall signal and different error signals is obtained. The method has been tested by measuring the Hall mobility of electrons in γ-irradiated KCl. μH=1.0 exp(646/T) cm2·V−1·sec−1 with μH=9.0 cm2·V−1·sec−1 at 300 K.
Low Temperature Apparatus for High Pressure Mössbauer Studies
Authors: Williamson D. L. , Bukshpan S. , Ingalls R. , Shechter H.
Published: February 2004

Relatively simple apparatus for lowering the temperature of a sample subjected to a very high pressure is presented. The pressure system is of the supported anvil type and can produce pressures in excess of 200 kilobars. Either a liquid nitrogen flow system or a liquid helium cryostat is used to cool the pressure cell. The pressure transmitting column is made of a special low conductive grade of fiberglass. Sample temperatures of 14 K at pressures up to 170 kilobars can be obtained.
Unsteady Radiant Heating of Conical Foil Receptors
Authors: Saunders Robert C.
Published: February 2004

The time dependent thermal equations of two types of conical radiation detectors are discussed and solved for a step function application of radiation parallel to the axis of the cases. The first type has a heat sink at the base and the second has the vertex buried in a heat sink to a variable proportion of its total height. It is found that the first case has the lower sensitivity and better time response. The time response of the second case is improved by more deeply burying the vertex, but to the detriment of sensitivity. At no value of this inclusion can both a superior sensitivity and time response be achieved for the second case.
A Quantitative Detector for Neutral Particles
Authors: Barnett C. F. , Ray J. A.
Published: February 2004

A neutral particle detector has been constructed and calibrated for H, He, and N atoms in the energy range 0.5–50 keV. These neutral particles were incident on a Cu or AgMg surface that emitted secondary electrons which were accelerated to 20 keV. These energetic electrons were collected by a silicon barrier detector from which the pulse height spectrum was shown to obey Poisson statistics. From the statistical distribution the detector efficiency was determined. The efficiency of the detector increases from 77% at 0.5 keV to 100% at 2 keV and remains constant at approximately 100% up to 50 keV. Measurements and results are presented for secondary electron and reflection coefficients for electrons and H incident on various surfaces.
Comparison Rheometer
Authors: Limpert J. C. , Schatzberg P.
Published: February 2004

A portable comparison rheometer for evaluation of fluids exhibiting drag-reducing properties has been designed, fabricated, and evaluated. Based on mechanical principles and requiring no external source of power, the apparatus is simple to operate. The device measures the effect on rheological properties of as little as 1 part per million polyethylene oxide in water and can distinguish variations in concentration in the range 0–30 parts per million.
A Well Defined Thermal Shock Transient Test Burner
Authors: Spicer W. C. , Ross P. T. , Newman R. L.
Published: February 2004

A test apparatus for producing calibrated thermal transients in ceramic specimens is described. It consists of a gas-air burner modified to allow the gas temperature to vary at 1390 K/sec in both heat-up and cool-down modes. Flat plate heat transfer up to 1800 W/m2·K is achievable. By using a known heat transfer environment, the thermal stresses in a test specimen can be compared with those produced in an operational engine.
Analog Plasma Diagnostic System
Authors: Nordlund D. R. , Breaux O. P.
Published: February 2004

The simple electronic diagnostic system described provides a calibrated oscilloscope display of a Langmuir probe I-V characteristic, its first and second derivative curves, the electron energy distribution function, and the ``cumulative'' electron number density. The system also provides a simple method for determining plasma potential and—if it exists—the electron temperature. Data taken in a low temperature mercury discharge are compared with data taken by means of the well known harmonic second derivative technique. An electron number density of 4.9×1016 m−3 and an electron temperature of 9.7×103 K found with the new system compare very favorably to values of 4.7×1016 m−3 and 9.9×103 K determined from the harmonic second derivative data. The system described features more rapid data reduction and lower cost than harmonic systems.
Cylindrical Mirror Analyzer with Surface Entrance and Exit Slots. II. Relativistic Part
Authors: Sar-El H. Z.
Published: February 2004

The relativistic treatment of the cylindrical mirror analyzer with surface entrance and exit slots is presented. Theoretically, its operation was found to be entirely unrestricted by the relativistic effect even for ultrarelativistic particles. A comparison of this device with other double focusing magnetic and electrostatic analyzers is presented.
Double Pulse Measurements of Avalanching p-n Junction Submicrosecond Transient Thermal Response
Authors: Nigrin J.
Published: February 2004

A method is presented for measuring the transient thermal response of avalanching p-n junctions. The transient response as close as 50–100 nsec after the step-like change of the power dissipation at the junction can be measured with an accuracy of ±0.4°C and about 40 nsec. Experiments show a sharp change of junction temperature, approaching closely the square root time dependence, during the first microsecond after the change of power dissipation.
A High-Voltage Current Regulator for Laser Gas Discharge Tubes
Authors: Posakony Michael J.
Published: February 2004

The design and applications of high voltage range series current regulators are discussed. A sample design maintains the current to within 1% of a selected value between 100 μA and 50 mA over a 15 kV voltage range. The regulator is ideal for regulating or pulsing laser gas discharges. The circuit can also be used as a high output voltage amplifier; in this service it can deliver 10 kV at 5 kHz with 1.4% total harmonic distortion.
A Multiampere DuoPIGatron Ion Source
Authors: Davis R. C. , Morgan O. B. , Stewart L. D. , Stirling W. L.
Published: February 2004

An ion source consisting of a duoplasmatron feeding a PIG discharge system has been built and is named a duoPIGatron. The extraction electrodes, located at the end of the PIG discharge opposite the duoplasmatron, are accel-decel with a 5 cm diam and multiapertures. The source is simple, flexible, and efficient. 1 A beams are extracted in steady-state operation with ion energies from 1.5 to 5 keV. 4 A beams are extracted with 0.1 sec pulses and a 10% duty cycle at ion energies of 20 to 40 keV. At 30 to 40 keV, about 60% of the ion beam is within a half-angular divergence of 1.2° with no magnetic lens. Using a hydrogen gas cell this system produces 2.6 A (equivalent) of 17.5 and 35 keV H0 particles within a half-angular divergence of 1.2°. One of the present limitations in scaling the source to larger beams is the current capabilities of the power supplies. As larger supplies are available attempts will be made to scale this system to the 10 A beam modules needed for future fusion research.
An Improved Method for Locating Charged Particle Tracks in Thin Plastic Sheets
Authors: Geisler Fred , Phillips P. R.
Published: February 2004

A new electrical method is presented for locating tracks of charged particles in very thin plastic sheets. Short high voltage pulses are employed rather than the steady voltages used previously. The method is applicable to plastic sheets of large area and of thickness down to 3.5 μ. The background is low and the efficiency greater than 85%.
Apparatus for Environmental Friction-Adhesion Studies Using Ultrahigh Vacuum Techniques
Authors: Aldrich R. G. , Hunt G. M.
Published: February 2004

An apparatus is described for the real-time analysis of sliding friction and normal force adhesion phenomena using ultrahigh vacuum techniques. Developed for the purpose of investigating the effects of surface cleaning, temperature, and deliberate gaseous contamination on the adhesion behavior of selected candidate materials for use in the NERVA nuclear rocket engine program, the system was designed to measure contact resistance by a four terminal ac (constant current-voltage drop) instrument calibrated in resistance. Using a torsion balance technique the relationship between the normal compressive load applied across crossed rod samples and the resultant contact resistance is used to ascertain the extent of contact area growth under anticipated service conditions. The apparatus can accommodate sample temperatures to 3000 K and maintain gaseous environments from pressures of 1 atm to 10−11 Torr. Contact resistance in the range 103–10−4 Ω, normal compressive loads from 1 mg to 600 g, and/or tangential loads to 155 g are displayed continuously in an analog fashion. Contact resistance data taken for a variety of metallic, intermetallic, and graphitic materials combinations have indicated the rate and extent of contact area growth to be expected during service and the effectiveness of gaseous lubricants in preventing adhesion. Typical data are presented for the materials combination 440C stainless steel vs 440C stainless steel.
A Counting Interval Normalization Circuit for Low Signal Level Spectroscopy
Authors: Hathaway C. E. , Rahn Larry A.
Published: February 2004

Low signal level spectroscopy often requires long data accumulation periods per spectral position. If the data are acquired in digital form, the accumulation period per spectral position must be adjusted to correct for fluctuations in the power output of the excitation source. A circuit has been designed which monitors the source and adjusts the data accumulation period to normalize it to the source power output. The circuit has been applied to Raman scattering experiments to demonstrate its performance.
A Fast Thermal Pulser for Metallic Phase Transformation Studies
Authors: Forgacs Robert L.
Published: February 2004

A thermal pulser utilizing I2R heating was developed for phase transformation studies in metals. The pulser combines fast rise and fall times and a feedback controlled, flat topped temperature pulse. The temperature sensor is either a three-legged thermocouple arranged to cancel out IR drops due to current in the sample, or a radiation thermometer. Sample and thermocouple fatigue life were materially improved by employment of a sample mounting arrangement which combined prestretched spring clamps to eliminate sample bowing and a symmetrical design to essentially eliminate transverse magnetic forces on the sample. Measurements show peak temperature of consecutive pulses repeatable to approximately ±1%, and temperature during a pulse from 0.1 to 10 sec in duration constant to approximately ±0.7–1.5%, even for metals with high thermal conductivity. The power capability is adequate to melt thin samples of most metals.
Instrumentation for Measuring Magnetic Transitions in the Temperature Range 4.2–300 K
Authors: Rothwarf F. , Ford D. , Dubeck L. W.
Published: February 2004

An inexpensive variable temperature probe which operates in the range 4.2–300 K is described along with instrumentation for measuring changes in susceptibility with great accuracy.
Apparatus for the Measurement of Small Angles
Authors: Tong A. H. , Gorey E. F. , Schneider C. P.
Published: February 2004

Small angles, 30′ or less, cannot be measured with sufficient accuracy by a goniometer. The newly developed small-angle measurement apparatus (SAM) described here is capable of measuring angles as small as 6′ with a precision of 2%. Theoretical calculations are compared with experimental results derived from both SAM and the goniometer. While this technique was developed for application to polished silicon wafers, it can be used to measure small angles on any reflecting surface.
Carbon Resistors as Low Temperature Thermometers
Authors: Kopp F. J. , Ashworth T.
Published: February 2004

Several specific types of carbon resistors (8 Allen-Bradley and 2 Speer) have been evaluated and compared as low temperature thermometers. Some of the samples demonstrated a reproducibility of about 0.5 mK on cycling between room and helium temperatures after they had been aged. Low resistance types (nominally 2.7 and 10 Ω) exhibited an abrupt change in their resistance-temperature relationship at 20 K. Standard type BB and EB Allen-Bradley resistors are useful thermometers; in addition to their reproducibility, they have a smooth resistance-temperature characteristic which does not have a minimum and which has a useful temperature coefficient throughout the range 4–300 K.
A Self-Lubricating Drive Screw for Use in High Vacuum Systems
Authors: Brown G. Ronald , Sowinski Peter J. , Pertel Richard
Published: February 2004

This note describes a stainless steel drive screw, lubricated by a solid Teflon insert, which is useful in high vacuum systems.
Determination of Film Thickness or Ion Etch Rate Using Auger Electron Spectroscopy
Authors: Yasko R. N. , Fried L. J.
Published: February 2004

The use of Auger electron spectroscopy for the determination of film thicknesses or ion etch rates is described. Because of its simplicity the technique may be preferable to conventional methods such as the microbalance and interferometry techniques.
Copper Wire Thermal Feedthrough for Use at Low Temperatures
Authors: Crabtree G. W. , Ketterson J. B. , Kuchnir M. , Roach P. R.
Published: February 2004

Construction of a thermal feedthrough which is useful at ultralow temperatures and high magnetic fields is described. The thermal link consists of several thousand small diameter copper wires which are capable of making good thermal contact to liquid helium while minimizing the effects of eddy current heating.
An Ozone Flow Metering System
Authors: Bogan D. J. , Hand C. W. , Obenauf R. H.
Published: February 2004

An apparatus to monitor ozone flow rates in the range from 5×10−9 to 10−5 mole·sec−1 has been designed and built. Flow measurement is accomplished by timing the pressure drop from a calibrated volume, along with simultaneous photometric determination of ozone partial pressure.
A Method of Improving Energy Resolution and Increasing Target Thickness in 180° Electron-Nucleus Scattering
Authors: Rand R. E.
Published: February 2004

A device is proposed which improves the quality and range of 180° electron nucleus scattering experiments. It consists of a short accelerating structure placed immediately upstream of the target and powered in such a way that it compensates the ionization energy loss suffered by back-scattered electrons, thus improving both resolution and signal to background ratios. With such a device, resolution is determined mainly by straggling in the target and target thicknesses up to 20 times those permitted by a conventional apparatus may be used.
Growth of Large Single Crystals. Ce2Mg3(NO3)12·24H2O (CMN)
Authors: Fisher R. A.
Published: February 2004

An apparatus and method is described for the growth of large, flawless, high-purity, oriented, single crystal cylinders (at least 50 mm in diameter by 55 mm long) of cerous magnesium nitrate 24 hydrate [Ce2Mg3(NO3)12·24H2O; (CMN)]. The CMN single crystals are grown at 30 °C in an air thermostat by evaporation of a saturated aqueous solution using reagent H2SO4 (98 wt %) as a desiccant for H2O removal. Growth is in a cylindrical container with the c crystal axis oriented parallel to the cylinder axis. The container and crystal orientation limit growth in the fastest growing directions perpendicular to the c axis. Rate of growth parallel to the c axis is set at 0.9 mm/day. Large single crystals are assured provided the procedure described is followed rigorously. Fabrication of the CMN cylinders into spheres and the location and marking of the crystal axes are also described. A spark source mass spectrometer analysis of pieces of such CMN crystals gave an impurity level expressible as 615 < atomic ppm impurities <1710 (atomic ppm relative to Ce). It is suggested that the apparatus and method may find general use in the growth of large single crystals of other substances, perhaps with a modification to allow continuous solution addition.
Improved Fast Response Pressure Gauge for Shock Reflection Studies in Ionized Gases
Authors: Hanson Ronald K. , Baganoff Donald
Published: February 2004

An improved design is presented for a fast response pressure gauge (0.1 μsec risetime) suitable for short duration measurements on the end wall of a shock tube. The design includes standard components to facilitate gauge construction, and it utilizes dual capacitive sensing elements together with a signal differencing scheme to permit use of the gauge in ionized gases. Pressure-time records obtained with the gauge are presented showing details of pressure profiles on the shock tube end wall for reflecting shock waves in ionized gases.
A Double Beam Single Detector Wavelength Modulation Spectrometer
Authors: Welkowsky M. , Braunstein R.
Published: February 2004

A double beam single detector wavelength modulation system has been developed which effectively eliminates the contribution of the background to the observed spectra. With this system, weak structure not apparent in a conventional measurement can easily be detected, with a sensitivity limited by the photon shot noise. The technique is applied to the determination of the band structure of semiconductors.
Fluorescence Activated Cell Sorting
Authors: Bonner W. A. , Hulett H. R. , Sweet R. G. , Herzenberg L. A.
Published: February 2004

An instrument has been developed for sorting biological cells. The cells are rendered differentially fluorescent and incorporated into a small liquid stream illuminated by a laser beam. The cells pass sequentially through the beam, and fluorescent light from the cells gives rise to electrical signals. The stream is broken into a series of uniform size drops downstream of the laser. The cell signals are used to give appropriate electrostatic charges to drops containing the cells. The drops then pass between two charged plates and are deflected to appropriate containers. The system has proved capable of providing fractions containing large numbers of viable cells highly enriched in a particular functional type.
Three-Axis Goniometer for EPR Sample Orientation
Authors: Batley M. , Bramley R. , Merz B. E. , Orr W.
Published: February 2004

A goniometer is described which is suitable for EPR sample orientation over the temperature range from ambient to the lambda point of liquid helium. It permits 360° rotation of the sample about one axis and total variations of 30° about each of two other orthogonal axes.
Simple Helium Flowmeter for Dilution Refrigerators
Authors: Niinikoski T. O.
Published: February 2004

This flowmeter measures the molar flow rate of 3He and 4He gas, independently of pressure or isotopic composition. The principle is based on the constant Cp. A calibration is needed for high accuracy.
X-Ray Premonochromator for a Picker Vertical Axis Diffractometer
Authors: Schuster Sanford L. , Weymouth John W.
Published: February 2004

An x-ray premonochromator designed for a Picker vertical axis diffractometer is described. The system is designed to allow an easy conversion from the monochromator to the no-monochromator configuration. The straightforward alignment of the monochromator is discussed.
Calculated Ionization Volumes for Batch, Continuous, and Selective Extraction Sources of Heavy Ions
Authors: Darling R. L. , McShan D. L. , Davis R. H.
Published: February 2004

Confinement time and ionization volume calculations have been made for batch, diffusive continuous, and selective extraction types of highly ionized, very heavy atom ion sources. For each source, the results are given for step-by-step only ionization by an energetic electron flux (1011 e/cm3 at 10 keV) and for ionization which includes the Auger effect. These are compared for loss conditions which vary from no loss to a loss cross section 0.05 times that of the 0 → 1+ionization cross section. For low loss, the ionization volume is least for the selective extraction source, while for a lossy source, the batch process becomes competitive. Volumes for the diffusive continuous source are the largest in all cases. Introduction of the Auger effect reduces the volumes by a factor of 2–10 in all but the diffusive continuous source. The ionization volumes required for an output of one particle microampere of Xe25+ are calculated for the different types of sources.
Fast Coaxial Flashlamp Pumped Liquid Dye Laser for Photolysis
Authors: Bunkenburg J.
Published: February 2004

This paper describes a fast risetime flashlamp pumped liquid dye laser employing a coaxial lamp, coaxial capacitor, and maintaining a coaxial configuration throughout the system.
Characteristics of the Trochoidal Monochromator by Calculation of Electron Energy Distribution
Authors: Roy D.
Published: February 2004

The properties and characteristics of the trochoidal monochromator, improved by Stamatovic and Schulz for producing low-energy monoenergetic electrons, are investigated by means of a method of calculation of the electron energy distribution. By assuming that the angular divergence of the incident beam is approximately 10°, the calculated energy distribution has a half-intensity width of 0.015 eV compared to 0.02 eV measured by Stamatovic and Schulz. Further calculations show that by changing some of the operating conditions it is possible to gain either an improvement of about 35% in the resolving power for the same transmission, or an improvement up to 100% in the transmitted current intensity for the same resolving power.
Simple Kinematic Laser Mirror Mount
Authors: Bergmann Ernest E.
Published: February 2004

A simple kinematic laser mirror mount is described which permits one to orient an optical component about vertical and horizontal axes which, to lowest order, pass through the center of the component. The use of magnets permits rapid interchange of optics without loss of orientation.
Triplet Pulse Sequences in the Measurement of Long Nuclear Spin Lattice Relaxation Times
Authors: Dinesh  , Rogers Max T. , Vickers G. D.
Published: February 2004

The use of triplet pulse sequences makes it possible to measure nuclear spin lattice relaxation times in a single scan, an advantage for liquids with long T1's. One appropriate pulse sequence is discussed, the optimum conditions for obtaining precise T1 values are outlined, and a technique for obtaining 90° pulses of the necessary accuracy is described.
Reduction of Dark Current in Photomultiplier Tubes
Authors: Davies W. E. R.
Published: February 2004

A method of reducing the dark current in photomultiplier tubes at room temperature is described. The simple procedure can result in improvements of several orders of magnitude in both side and end-on cathode types.
A New Method for Determining the Cross Section of a Moving Arc Column
Authors: Paulson R. , Pfender E.
Published: February 2004

A new method for measuring the cross sectional size of the near anode arc column on a relative scale for a moving arc column makes use of potential and conductance probes. The method permits one to determine the shape of dc arc columns under cross flow conditions and the variation of the arc cross section within the viscous boundary layer of an anode.
Stabilization of Holographic Recording Systems with Intermittent Exposure Control
Authors: Pernick B. J. , Kesselman M.
Published: February 2004

A new passive hologram stabilization method has been devised in which intermittent exposure control is used to ``stop'' the motion of the fringe field to be recorded. This system can be effectively employed as the sole stabilization method, or coupled with other known techniques to upgrade performance. The effectiveness of intermittent exposure control in the presence of strong disturbances is demonstrated by experimental results. Efforts concerning implementation options are also presented.
Low Temperature Semiconductor Potential Sampling Probe
Authors: Malleck H. , Seifert F. , Kranzer D.
Published: February 2004

A low temperature electrical point contact probe to scan the potential linearly along semiconductor rods at temperatures between 2 and 300 K is described. The construction facilitates an exact readability of the position of the continuously adjustable probe. The contact pressure is determined by weights independent of the probe position. Measurements in a static magnetic field are feasible.
A Centrifugal Manometer for Use in Rotating Systems
Authors: Bragg G. M.
Published: February 2004

A technique is presented for measuring pressure differentials in a rotating reference frame with the aid of a stroboscope. The technique is mechanically simple, does not require seals, and is an absolute reading device.
Flow Channel Cell Apparatus for High Rate Electrolysis Studies
Authors: Landolt Dieter
Published: February 2004

A simple flow channel cell apparatus is described which is suited for high rate electrolysis studies under well controlled hydrodynamic conditions. The design includes a discontinuously operated piston pump which presses the electrolyte through the electrochemical cell at linear velocities of up to 2000 cm/sec. An electrolyte volume of less than 2 liters is required for the operation of the apparatus. No metal parts except the electrodes are in contact with the solution. Mass transfer characteristics of the flow channel cell have been determined by measuring limiting currents for the reduction of ferricyanide.
An Air-Driven Oil Pump, a Valve, and a Connector for 20 Kilobars
Authors: Whalley E. , Lavergne A.
Published: February 2004

A mechanical pump for 20 kilobars that is driven by a 7 kg·cm−2 air supply is described. In a test, in which it pumped fluid into a constant pressure of 20 kilobars or more at the rate of 30 strokes per minute, it made well over 300 strokes before the seal failed. A valve that will operate with 20 kilobars on either side of the stem is described. An O-ring seal is used to seal the shaft. The torque required to close the valve is reduced by taking the thrust of the pressure on the stem by a ball thrust bearing, and is only 0.5 m·kg at full pressure. Finally, a connector for joining pieces of apparatus together without the necessity of an intermediate piece of tubing is described.
A Dual Needle Piezoelectric Micromanipulator for the Scanning Electron Microscope
Authors: Pawley James B.
Published: February 2004

A three-stage micromanipulator for the scanning electron microscope (SEM) is described incorporating coarse and fine mechanical drives and a very fine piezoelectric drive which can independently position two separate probes. Each piezoelectric drive has an accuracy of 0.1 μ over a range of 100 μ in each of three directions and a very rapid response. They are mounted near the specimen on a 9.5 mm diam rod the position of which is controlled by the mechanical drives which operate outside the vacuum. The rod and piezoelectric drives can be retracted into the airlock for easy removal. The fine mechanical drive is composed of three feedback-controlled motor-driven differential screws which have a range of 1.25 mm and an accuracy of 3 μ. The coarse drives are manually driven and have a range of 1 cm and an accuracy of 0.1 mm. Joysticks control coordinated motions in the plane of the SEM image for both the piezoelectric drives and the fine mechanical drive. Preliminary results in the microdissection of biological tissue are described.
Two Types of Magnetostrictive Wire Readouts for Spark Chambers
Authors: Buchanan C. D. , Everhart G. , Goldblatt I. D. , Kraus D. , Lande K. , Long R. , Lowenstein D. I. , Niederer J. A. , Potter D. C.
Published: February 2004

Two types of magnetostrictive wire readouts are described. One is a multiwire nickel arrangement for use in magnetic fields (∼200 G). The other type employs a dual pickup on a single Remendur wire and removes uncertainties in spark location which are caused by spark width and spark formation time.
A Passive Calorimeter for Pulsed Electron Beam Energy Measurement
Authors: Stephens H. P. , Donaldson A. B. , Heckman R. C.
Published: February 2004

A passive calorimeter for diagnostics of high energy pulsed electron beams is described. It consists of a thin rectangular sheet which is irradiated by the electron beam in a central region. The generated heat diffuses outwardly to the ends so that each position experiences a temperature maximum. Thin strips of materials which melt at various temperatures are coated on the surface to provide a record of the temperature maxima of the calorimeters. The corresponding heat diffusion problem is analyzed and used with the experimental results to calculate the initial temperature of the irradiated region, and thus the dose. The calorimeter absorbs only a small fraction of the beam energy and is therefore useful for making dose measurements simultaneously with experiments.
A 100 kV, Fast, High Energy, Nonuniform Field Distortion Switch
Authors: Post R. S. , Chen Y. G.
Published: February 2004

A fast closing, high voltage, high energy, nonuniform field distortion switch has been developed. This switch, filled with free-flowing one atmospheric sulfur-hexafluoride gas, operates in the cascade mode, and is able to handle 36 kJ at 85 kV. These switches have been tested and put into operation with the Columbia high voltage capacitor bank. The over-all jitter between the six switches used is less than 10 nsec at 85 kV.
A High Precision Cryostat for Reflection and Transmission Studies
Authors: Kachare A. H. , Layfield J. D. , Andermann G.
Published: February 2004

A metal cryostat with novel features has been designed and built for infrared reflectance and transmission measurements. The problem of obtaining precise measurements has been solved by careful evaluation of reflection losses due to the optical windows, and by achieving exact optical coplanarity between the sample and reference mirror. At all temperatures down to liquid helium temperature, the precision of the measurements obtained is significantly better than that reported so far in the literature.
A New Principle for Aqueous Sample Cells for EPR
Authors: Hyde James S.
Published: February 2004

If an aqueous sample cell is arranged such that the electric field vectors in the cavity are substantially perpendicular to the surface of the cell, a good cavity Q is observed and high quality EPR signals can be obtained. Polarization charges induced on the surface of the sample cause a very marked reduction of the electric field strength in the sample compared with that in the cavity, and the dielectric loss is small. The rf magnetic flux density B as determined by EPR experiments is substantially unchanged, indicating that ▿×E in the sample is unchanged.
A Cavity Type Absorption Cell for Double Resonance Microwave Spectroscopy
Authors: Lee M. C. , White W. F.
Published: February 2004

An experimental dual resonant cavity absorption cell to observe microwave spectroscopic double resonance effects is described. This device is composed of two Fabry-Perot interferometers excited by independent microwave sources and mounted at right angles in a suitable vacuum enclosure. The pumping transition is modulated by one source and the modulation induced on the rf absorption in the orthogonal cavity is detected. Preliminary experimental data are presented to show signal amplitude variations for two connected transitions of methylene chloride, 000 → 111=35 067.0 MHz and 111 ← 202=15 911.9 MHz, as microwave power levels and cavity Q's were varied. Sensitivities obtained are comparable to those of conventional Stark-modulated microwave spectrometers, and further improvements appear possible.