bluuebunny/crossref_metadata_2025 huggingface dataset:
Duoplasmatron Ion Beam Source for Vacuum Sputtering of Thin Films
Authors: Chopra K. L. , Randlett M. R.
Published: February 2005

A variation of the von Ardenne type of a duoplasmatron ion source is described. Here the arc discharge is maintained between the cathode in the high pressure and the anode in the vacuum chamber, as opposed to the conventional arrangement in which the arc discharge is confined primarily to the high pressure chamber. This modification allows the extraction, through apertures, of a well defined ion beam of current up to 500 mA over an area ∼1 cm2 into a vacuum chamber at a pressure of ∼10−5 Torr. The ion beam is accelerated and made to impinge on a target material for sputtering. Sequential sputtering of different targets inside the vacuum chamber is possible with the help of suitable magnetic fields. The ion beam has been used to sputter conducting, semiconducting, and insulating target materials. Typical rate of deposition of silver films at a distance of 8 cm from the target with a 50 mA, 2 kV ion beam of 8 mm diam is ∼400 Å/min. Deposition rates of ∼50 Å/min are obtained for SiO2 and TiO films. Vacuum sputtered films adhere to the subtrates much more strongly than the evaporated films do. Gold and silver films grow epitaxially on rock salt substrates at ambient or lower temperatures. This vacuum sputtering process has been found to induce and stabilize new structures. For example, sputtered films of molybdenum, tantalum, tungsten (normally bcc), and hafnium, rhenium and zirconium (normally hcp) have been observed to exist in an fcc phase. Fcc structure films as thick as 2 μ have been prepared. Epitaxial growth of the fcc structures on rock salt substrates at temperatures of ∼400°C are observed.
Image Furnace for Low Yield Nuclear Weapons Effects Simulation
Authors: Griff Neil , Heilferty Robert J. , Derksen Willard L.
Published: February 2005

The capability of the Naval Applied Science Laboratory for direct simulation of thermal effects due to nuclear weapons has been extended to low yield devices [as small as 10 kilotons (kt)] by the installation of a high performance servo-driven shutter in a carbon arc imaging furnace. The system can simulate thermal radiation pulses from atmospheric detonations with yields of from 10 kt to the largest devices. It can deliver a maximum irradiance of 190 J cm−2 sec−1 over an effective spot diameter (irradiance at least 90% of maximum) of approximately 17 mm using a single ellipsoidal mirror. With the addition of a second mirror, a maximum irradiance of over 850 J cm−2 sec−1 can be obtained with an effective spot diameter of about 4 mm. Arbitrary pulse shapes can also be delivered. Provision is made to record irradiance histories and source characteristics during each exposure without appreciably interfering with sample irradiation.
Device to Measure the Voltage-Current Relations in Biological Membranes
Authors: La Force Richard Conley
Published: February 2005

A device has been designed and constructed, largely of commercially available operational amplifiers, to measure the voltage-current relations in biological membranes due to the ion flux through them. The device operates in three modes: to clamp the voltage across the membrane to some predetermined value and record the current, to clamp the current through the membrane and record the trans-membrane voltage, and to record dV/dI, the resistance of the membrane measured in a time short compared to the ion redistribution time.
Cryostat for Studies at ∼100 Kilobars at Liquid Helium Temperatures
Authors: Lyon D. N. , McWhan D. B. , Stevens A. L.
Published: February 2005

A cryostat to transmit the load of a 270 ton press to a chamber at liquid helium temperatures is described. The pressure transmitting columns are made of an epoxy resin-bonded glass fiber laminate. The liquid helium consumption is ∼10 liters to cool from ∼70 to 4.2°K, and the boiloff rate is ∼1.2 liters. Measurements of the electrical resistance of bismuth between 4.2 and 77°K at different pressures up to ∼85 kilobars were made using a Bridgman anvil (1.27 cm face) geometry.
Very Precise 30 Nanosecond Linear Gate
Authors: Manfredi P. F. , Maranesi P. , Rimini A.
Published: February 2005

After a short theoretical exposition of a method for compensating inaccuracies in parallel-diode switch-gates, a linear gate circuit is presented which is based on the described principle. Accurate measurements of differential linearity error in the whole dynamic range (0–10 V) have been done. The results of experimental checks of rise time, pedestal, rejection factor, and thermal stability are also given. The circuit which operates with gating pulses longer than 30 nsec is believed to introduce a considerable improvement in comparison with previously given solutions, mainly from the linearity point of view.
Accurate and Straightforward Alignment Procedures for X-Ray Diffractometers Equipped with a Eulerian Cradle
Authors: Samson Sten , Schuelke William W.
Published: February 2005

This paper describes the kind and sequence of measurements that lead to an accurate assessment of all instrument parameters of an x-ray diffractometer that incorporates up to six axes of rotation. Included in this description are determinations of the zero settings of 2θ, ω, and χ with or without the use of x rays. Each parameter can be uniquely determined, one at a time, in a completely straightforward manner with the use of only two tools, the autocollimator and the dial indicator, and a small assortment of special fixtures. A few design features are outlined that facilitate alignment checks. Directions for the alignment of a number of components are given, and can be performed by the user, thereby eliminating the need for expensive machining. A brief discussion of some serious errors caused by defective counters is also included.
High Emission Photocathode for Swarm Experiments
Authors: Moruzzi J. L.
Published: February 2005

A device for obtaining relatively large photocurrents from small ultraviolet light sources is described. The device has several advantages over the conventional techniques that are currently used and is well suited for use in experimental studies that require a cold electron source. In this connection it has been successfully used as the electron source in a high pressure ion source of a mass spectrometer.
Reversible Precounter for Photon Counting
Authors: Helman W. P. , Schutt D. W.
Published: February 2005

The conversion of a Cary model 14 spectrofluorimeter to photon counting with automatic background noise subtraction is described. For purposes of economy and rapid conversion, an existing events counter-timer was used and a reversible precounter made to accomplish the noise subtraction.
Dead Weight Piston Gauge for Pressures to 26 Kilobars
Authors: Johnson D. P. , Heydemann P. L. M.
Published: February 2005

The design and operation of a dead weight piston gauge for pressures to 26 kilobars is described. The gauge is of the controlled clearance type. The diameter of the gauge piston is 0.2 cm. It is loaded directly with up to 840 kg of weights. A volume of about 1 cm3 is provided inside the gauge for the material under test. The use of this gauge for transition pressure determinations is briefly discussed.
A One-Shot Multivibrator Anticoincidence and Recording Circuit
Authors: Toit S. J. du
Published: February 2005

A description is given of a circuit using two one-shot multivibrators, which can be used in experiments where large numbers of counter tubes are to be used in anticoincidence. Only vacuum tubes are used in the construction. The circuit has a 100 percent efficiency, and its operation is wholly independent of the shape and duration of the coincidence or the anticoincidence impulses. When operating with up to 100 large Geiger-Müller tubes in anticoincidence less than 1 percent of the real anticoincident counts are suppressed owing to the blocking effect of the anticoincidence multivibrator. The same principle is used in the construction of a recording circuit which also uses only hard vacuum tubes, and which is able to actuate any fast impulse counter at its maximum speed, without jamming.
An Instrument to Measure Servomechanism Performance
Authors: Tarpley H. I.
Published: February 2005

A transient recorder of the ``memory'' type for measuring transients applied to positioning servomechanisms is described in some detail. Essentially, the recorder consists of a bank of condensers, on which the transient voltages are successively impressed and later read off a CRO screen and plotted as a function of time to reveal the nature of the transient. In recording a transient, errors not exceeding ten percent are to be expected of the equipment. Rapidity of recording transients is one of the chief advantages of the system. Equipment for measuring the amplitude and phase response of a servomechanism, when subjected to an alternating input of variable frequency, is described. The measurement of the phases of input and output angles of a positioning servo is accomplished by means of a commutator driven by the sine wave generator, which supplies the alternating input to the servomechanism. The commutator has but one bar, and a vacuum tube voltmeter is connected to an angle-measuring synchro, once each cycle, by a brush which may be moved to find the zero point of the modulated wave representing the alternating input. The phase angle between the input and output may be read as the difference between the angle positions of the brush used to locate the zero point of the modulated waves of the input and output. Phase angles may be measured with an error not exceeding one degree.
Hydrogen Recoil Proportional Counter for Neutron Detection
Authors: Coon J. H. , Nobles R. A.
Published: February 2005

A proportional counter utilizing recoiling protons ejected from a thin hydrogenous radiator by elastic collision with incident neutrons is described in its design and its response. Comparison between experimental and calculated curves for sensitivity versus neutron energy, and sensitivity versus counting bias, indicate that the response of the counter is calculable. It may be used as a directional threshold neutron detector, the value of the threshold being open to arbitrary choice.
A Recording Vacuum Grating Spectrometer for the Infra-Red
Authors: Bell E. E. , Noble R. H. , Nielsen H. H.
Published: February 2005

A description is given of a recording vacuum grating spectrograph for the infra-red region of the spectrum from 1 micron to 30 microns. The description contains the details of the recording and amplifying system and the method for stabilizing the power from the radiant source. Typical records are shown of well-known infra-red spectra. The lines from the two isotopes of HCl are completely separated in the fundamental band obtained in first order. The rotational lines of the 4.3-micron band of CO2 are completely separated in the first-order spectrum. In most parts of the spectrum it is possible to resolve lines separated by intervals less than 1 cm−1.
Speed Control for the Air-Driven Centrifuge
Authors: Beams J. W. , Linke F. W. , Sommer P.
Published: February 2005

A method based on some work of Thomas Davis is described for controlling the rotor speed of an air-driven ultracentrifuge. A permanent magnet mounted on the shaft of the centrifuge induces an e.m.f. in a series inductance, capacity resistance circuit which has the same frequency as the rotor. When the rotor speed approaches the resonance frequency of the circuit, energy is absorbed, and the driving air pressure versus rotor speed relation increases abruptly. By regulating the driving air pressure at a few lbs./in.2 above that necessary to maintain the speed of the centrifuge where resonance begins, the rotor speed is held constant to roughly 0.1 percent over the range of speeds employed.
An Automatic Arc-Current Regulator
Authors: Potter E. V. , Scott Arden
Published: February 2005

The desirability of eliminating errors in spectrographic analyses, resulting from fluctuations in arc current normally present in uncontrolled or manually controlled d.c. arcs, led to the design and construction of an electronic type of automatic current regulator. This regulator operates from a 250-volt d.c. supply, handles currents from 4 to 8 amperes, and maintains them within 0.02 percent per volt variation in arc voltage over a range of from 30 to 70 volts in arc voltage or 40 volts variation in supply voltage.

Oscillograms of the arc current and voltage during a typical run show no detectable fluctuations in the current and less variation in voltage than is normally present.

Standard curves obtained using the regulator are much more regular and reliable, and the individual points can be reproduced more closely than those from the uncontrolled arc. Analyses made using the regulator can also be reproduced more closely, and the results are in better agreement with chemical analyses than those obtained with the uncontrolled arc. In addition, the use of the automatic regulator eliminates the necessity for having an operator to regulate the arc current and the results obtained with one operator are better than two men could obtain without the regulator.
An Improved Electron Multiplier Particle Counter
Authors: Allen James S.
Published: February 2005

The design and construction of a 13-stage electron multiplier tube are discussed. Electrodes formed from BeCu alloy sheet are used and the method of activating these surfaces is described. The over-all multiplication of this type of tube is about 107. The efficiency of the tube as an electron counter is 100 percent for electrons of 500 ev and decreases to 40 percent for electrons of 6 kev. Preliminary results indicate that the efficiency as an alpha-particle counter is also 100 percent.
Ultrasonic Resonance Applied to Non-Destructive Testing
Authors: Erwin Wesley S. , Rassweiler Gerald M.
Published: February 2005

Ultrasonic vibrations of continuously varying frequency are applied to the part under test which is set into longitudinal vibration at its natural frequencies. The consequent reaction on the applicator is used to produce visible marks on a cathode-ray screen from which thickness of the part may readily be deduced.
On the Use of Alkali Metal Alloys for Trapping Mercury Vapor
Authors: Hunten K. W. , Woonton G. A. , Longhurst E. C.
Published: February 2005

In a mercury-vapor trap of appropriate design an alloy of sodium with 5 to 10 percent potassium is more satisfactory than either of the metals used alone. The trap does not need reactivation at intervals and, therefore, during its life affords continuous protection from mercury vapor. Over a period of twenty-two days a vacuum system protected by this type of trap was pumped repeatedly from atmospheric pressure to 5×10−7 mm of Hg; during this time the trap required no attention.
Two New Methods for Detecting Nuclear Radiofrequency Resonance Absorption
Authors: Roberts Arthur
Published: February 2005

Nuclear radiofrequency absorption can be observed by means of a super-regenerative detector. The sample is placed in the coil of the resonant circuit, and reacts to produce an observable signal by nuclear absorption when the external magnetic field is such as to produce a Larmor precession at the same frequency as that of the super-regenerative detector. An autodyne detector, oscillating weakly, can also be used to observe nuclear resonance absorption.
Absolute Capacitance Standard with a Resistive Shield
Authors: Slonczewski T.
Published: February 2005

The addition of a high resistance shield to the guard ring of a parallel-plate condenser reduces the fringe effect to a negligible value so that the precise computation of capacitance is simplified.
Automatic Integration of Linear Sixth-Order Differential Equations by Means of Punched-Card Machines
Authors: Hausman L. F. , Schwarzschild M.
Published: February 2005

It is shown how punched-card-relay calculators can be used for solving ordinary linear differential equations of sixth and lower order. The differential equations are replaced by difference equations which can be solved by the relay calculators automatically step by step. The final solution is obtained by repeating the integration several times, each time computing the truncation error and applying it as a correction in the subsequent integration.
A Precision Alpha-Proportional Counter
Authors: Simpson J. A.
Published: February 2005

An instrument is described which will detect and record the alpha-disintegration rate of prepared radioactive samples even though soft beta-radiation up to 5×109 disintegrations per minute may also be present. The counting losses arising from the detector, electronic amplifier, scaler, and recorder total 0.8 percent with an alpha-counting rate of 105 counts per minute. The instrument employs a proportional counter through which 99 percent CH4 at one atmosphere slowly flows. The proportional counting region is approximately 300 volts in length, with 0.5 percent change in counting rate in an interval of 200 volts. Thin radioactive samples deposited on metal disks up to 2.5 cm in diameter are easily inserted into the counter volume by means of a special gas lock. The counter detects 0.50 of the disintegrations from a thin radioactive sample. The counter background can be maintained at about 14 counts per hour. A high vacuum, low geometry attachment provides reductions in geometry down to at least 10−5 of the sample counting rate. Some theory of gas-flow proportional counters is presented along with details of the instrument construction.
A Device for Plotting Rays in a Stratified Medium
Authors: Lawson A. W. , Miller P. H. , Schiff L. I.
Published: February 2005

A device is described which was developed for the rapid computation of rays in a medium in which the index of refraction or speed is a function of only one rectangular coordinate. It was used during the war for the computation of sound fields in water in the ray approximation, and hence is called the sonic ray plotter. It could also be applied to the ray approximation solution of the problem of the propagation of radar signals in a stratified atmosphere, since it is possible to transform the curvature of the earth into an additional refractive index that depends only on the height above a plane earth.
An Electrophoresis Apparatus Using Parabolic Mirrors
Authors: Swingle Stanley M.
Published: February 2005

An electrophoresis apparatus with several improved features is described. Principal developments are the use of mirrors in the optical system, kinematic mechanical design, and a current regulating power supply.
An Alternating Current Probe for Measurement of Magnetic Fields
Authors: Gregg E. C.
Published: February 2005

A method of measuring magnetic field strengths is described which utilizes the incremental permeability of a small Permalloy core. Alternating-current excitation is used which in turn permits amplification and hence a relatively high sensitivity and accuracy.
Comparison of Supersonic Intensities by Means of a Magnetostriction Gauge
Authors: Smith Alva W. , Weimer David K.
Published: February 2005

A small magnetostriction gauge is described which can be used for the comparison of supersonic intensities. The gauge consists essentially of a small rod of nickel wound with a few turns of wire. The acoustic pressures present in the liquid produce changes in length of the rod which in turn, because of the inverse magnetostrictive effect, induces voltages in the coil.
Measurement of Transient Hydraulic Pressures
Authors: Montgomery L. H. , Ward James W.
Published: February 2005

In experiments in which it was necessary to record transient pressure waves in water, a recording instrument was sought which possessed the following characteristics: (1) a frequency response which was the same over a range from ½ cycle to 10 kilocycles per second, (2) a continuous pressure-time relationship in the recordings, (3) a range of sensitivity from about minus 200 pounds per square inch to several thousand pounds per square inch on the positive side, (4) the ability to be calibrated through the use of known hydrostatic pressures, and (5) relative freedom from artifacts. Several methods involving the use of piezoelectric crystals, electromagnetic pick-ups, balanced diaphragms, high speed stoboscopic pictures of small rubber balloons, and cylindrical wire strain gauges were employed and their characteristics analyzed. Only the cylindrical wire strain gauge met all of the requirements. It consisted of a length of fine resistance wire wound on a thin-walled, closed cylinder. The gauge operated through a bridge circuit into an amplifier and cathode-ray oscillograph. The structure, operation, and characteristics of this gauge are considered and compared with the other methods used for recording transient hydraulic pressures.
Reducing Potentiometer Loading Error
Authors: Nettleton L. A. , Dole F. E.
Published: February 2005

In the practical application of potentiometers to electrical computer circuits, loading errors are invariably present. Where linear outputs are required the loading errors can usually be held within reasonable limits by careful proportioning of constants and by working on the most favorable part of the characteristic curve. However, if this is not sufficient, the potentiometer card can be tapered in such a way as to eliminate the loading error. Potentiometer cards can also be tapered in order to produce non-linear functions. On the other hand linear potentiometers can be loaded so as to produce non-linear functions, as in the case of the ``Tangent Function'' potentiometer circuit. When the tangent function is not required for both positive and negative angles, the accuracy of the output can be improved by unbalancing the circuit.
Theoretical Consideration in Heat and Infra-Red Detection, with Particular Reference to the Pneumatic Detector
Authors: Golay Marcel J. E.
Published: February 2005

A brief mathematical review of the basic factors involved in infra-red detection is presented, with emphasis on the concepts of equivalent circuits and efficiency. A few theoretical aspects of the pneumatic detector are discussed.
Construction and Characteristics of Evaporated Nickel Bolometers
Authors: Billings B. H. , Barr E. E. , Hyde W. L.
Published: February 2005

Details are given of the construction of an evaporated nickel bolometer. These bolometers are approximately 200A thick and are evaporated onto a nitrocellulose pellicle approximately 1000A thick. The pellicle is supported on a glass base in which is a sandblasted groove. This groove is immediately below the area of the pellicle which is covered with the bolometer strip. The techniques are described which were used to measure the bolometer characteristics. The sensitivity and frequency response of the bolometer are discussed. A typical bolometer has a time constant of 0.004 second, and a threshold of 3.3×10−8 watt for radiation modulated sinusoidally at 30 cycles per second where the band width of the system is 100 cycles.
Extended Applications of the Hot-Wire Anemometer
Authors: Corrsin Stanley
Published: February 2005

The use of the hot-wire anemometer has been extended to include the measurement of temperature fluctuation level as well as temperature-velocity correlation, in a turbulent flow with heat transfer.

Secondly, the hot wire can be used for the determination of mean relative concentration in the mixing of two gases of different known thermal characteristics.

Finally, the instantaneous response of a hot wire in a turbulent flow with mixing of two gases of different thermal characteristics has been computed. This permits measurement of the concentration fluctuation level as well as the concentration-velocity correlation.
The Measurement of Ultra-Short Time Intervals
Authors: Neddermeyer S. H. , Althaus E. J. , Allison W. , Schatz E. R.
Published: February 2005

An instrument is described which utilizes the superposition locus of transient pulses traveling in opposite directions on a transmission line for a determination of the interval between the times of generation of the pulses. For testing purposes pulses are generated by discharging a short segment of line through a matching network into a closed loop so that equal pulses start simultaneously in opposite directions around the line. Two systems for pulse detection are described, one requiring repetitive pulsing, in which a detector is coupled to the line at any desired position, yields an output which varies as a function of position, and shows a maximum at the superposition locus; and another, not requiring repetitive pulsing, in which the outputs from multiple fixed detectors are recorded simultaneously. In the latter system the superposition locus appears as a maximum in the output peaks, which are recorded in one-to-one correspondence with the positions of the detectors on the line.

A measurement of the refractive index of polystyrene for pulses of duration about 2×10−10 sec. gave 1.48 with the first instrument and 1.45 with the second. The latter value is less certain than the first because of poorer resolution, and both are subject to an upward revision from an undetermined correction in the line propagation rate.
An Automatic Low Frequency Analyzer
Authors: Barbour Ian
Published: February 2005

An automatic device for continuous frequency analysis of complex slow waves is described. A vibrating bar serves as the tuned filter element which, through a heterodyne circuit, selects successively the frequencies whose amplitudes are recorded. Some examples are given of application in electroencephalography for which the instrument was developed.
Filters for Spectral Corrections of Multiplier Photo-Tubes Used from Scotopic to Photopic Brightness Levels
Authors: Plymale W. S.
Published: February 2005

The difficulties encountered in photometry at low levels of brightness are in a wide measure due to changes in the spectral characteristics of the eye as it becomes light- or dark-adapted. A study has been made of filter glasses suitable for correcting two types of multiplier photo-tubes used in photometric work where there is a wide variation in field brightnesses. Results of this study are described, and filter glass numbers as well as thickness specifications are given for filters used to correct RCA 1P21 and 1P22 tubes over brightness levels corresponding to the Purkinje range.
Electronics for Cosmic-Ray Experiments
Authors: Howland B. , Schroeder C. A. , Shipman J. D.
Published: February 2005

A method is described for detecting coincidence between the discharges of Geiger counters. The basic circuit uses diodes as coincidence tubes. The output from a diode circuit is the same polarity pulse as the inputs, hence the output from one coincidence circuit can be used to generate more complex coincidences. An example is given of a typical counter-tube experiment utilizing the diode scheme. A formula is developed for the ratio of output for total and partial coincidence in terms of the pulse width and circuit parameters; in a practical case with a pulse width of 1μ second a fourfold to threefold output ratio of 40 is obtained. Mention is also made of a combination diode-pentode coincidence circuit.
Metaborate Compounds for Internal Cyclotron Targets
Authors: Weil A. S. , Reid A. F. , Dunning J. R.
Published: February 2005

The use of NaBO2 as a target material for the preparation of radioactive Na24 through the deuteron bombardment reaction Na2311+1d2→11Na24+1p1is discussed. The general advantages of NaBO2 as a target material, compared to metallic sodium or other sodium containing compounds, are given, as well as the procedure for target preparation and the details of the chemical treatment used for the purification of the Na24.

The general use of metaborate targets is discussed briefly for other deuteron bombardment reactions in which an elementary target material is less practical to use.
Electrostatic Analyzer for Selection of Homogeneous Ion Beam
Authors: Warren R. E. , Powell J. L. , Herb R. G.
Published: February 2005

An electrostatic analyzer has been built for use with the high pressure electrostatic generator at the University of Wisconsin. The proton beam from the generator is deflected through a 90° arc of 40″ radius by means of a radial electric field between curved metal plates spaced 516′′ apart. Suitably disposed slits select a beam which has a very small energy spread. The apparatus has been operated with energy resolutions up to 5000, and preliminary tests have been made, using the 985- and 1020-kv γ-ray resonances in the reaction Al27+H1→Si28+hν.
Bridge Type Electrical Computers
Authors: Ergen William Krasny
Published: February 2005

The prototype of the computers in question is a Wheatstone bridge, with the resistances in two opposite legs proportional to two magnitudes, x1 and x2, respectively, and the resistance in a third leg proportional to x3. The fourth leg is adjusted to balance the bridge, either manually or by a servo mechanism. The resistance of the fourth leg is then proportional to x1x2/x3. This bridge can be generalized by replacing the resistors in each leg by a series connection of resistors, each of which is proportional to a variable. Such a bridge solves quadratic equations, but only if the equation is of rank 4 and signature zero. By connecting several resistances in parallel into each leg of the bridge, one can solve higher order equations. A bridge used for the solution of a quartic equation will be shown. The equation was the equation of a straight line in bipolar coordinates and was used to guide an airplane on a straight line when the distances of the plane from two fixed ground stations were known by Shoran.
A High Temperature X-Ray Diffraction Apparatus
Authors: Birks L. S. , Friedman H.
Published: February 2005

An apparatus is described for heating an x-ray specimen to 1200°C in vacuum while its diffraction pattern is being recorded continuously on a Geiger counter spectrometer. The heater consists of a length of 0.030-inch tungsten wire embedded in beryllium oxide, the whole enclosed in a polished tantalum case. Either a flat metal sheet, or powder packed in platinum gauze mounted on sheet metal is suitable as a specimen. An area about one centimeter square in the center of the specimen is irradiated by the x-ray beam in the focusing type of spectrometer. The temperature is uniform over this area to ±5 degrees centigrade. Two concentric radiation shields reduce heat loss. The outer shield also acts as the vacuum-tight body of the oven and has beryllium windows to pass the x-rays. Results indicate that rapid structure changes may be observed as they occur with this apparatus.
Determination of Vapor Pressures Below 10−3 mm Hg
Authors: Kapff S. F. , Jacobs R. B.
Published: February 2005

A method based on kinetic theory principles has been developed whereby the slope of the vapor-pressure temperature curve of a liquid can be obtained at 25°C when the vapor pressure is of the order of 10−7 mm Hg at this temperature. A simple apparatus consisting of a boiler, slit system, and target is used to determine a dew point of the material under high vacuum. From the temperature of this dew point the slope can be calculated directly. If in addition a single value is known by other methods for the vapor pressure in the region of 10−3 mm then the value at 25°C is easily found. The results are believed to be accurate to 30 percent, as contrasted with other methods which give errors of several hundred percent in this region.
Some Designs and Applications for Packaged Amplifiers Using Subminiature Tubes
Authors: Chance Britton , Thurston J. N. , Richman P. L.
Published: February 2005

Design and construction details of d.c. and a.c. amplifier packages using subminiature tubes are given. In addition, applications to control and measurement circuits are shown. The purpose of these amplifiers is to decrease the time lost in the construction and repair of complicated electronic equipment for biophysical and other experiments.
A Portable Pulse Generator
Authors: Titterton E. W. , Fitch V. L.
Published: February 2005

In the routine testing of electronic equipment, particularly in a nuclear physics laboratory, there is frequently a requirement for a simple, lightweight pulse generator. The instrument described is built to fill such a role. It provides rectangular pulses of duration 1, 10, and 100 microseconds (or other chosen values) of amplitude smoothly variable from 0 to 75 volts. Either positive or negative pulses are available from low impedance sources, and an internal repetition rate, covering the range 1 to 10,000 cycles per second, is included. In addition, the circuit may be driven from an external signal generator, or a source of random pulses, where this is desired. The instrument has proved of utility in circuit research when used as a source of pulses in conjunction with a synchroscope.
A Note on the Theory of Corrugated Diaphragms for Pressure-Measuring Instruments
Authors: Pfeiffer Alfred
Published: February 2005

A hypothetical model for the distribution of stress in diaphragms is discussed. It is constructed of members in series, with each consisting of one flexural and one tension spring acting in parallel. This hypothetical model lends to a correlation between pressure P acting on the diaphragm, corresponding deflection of the diaphragm h, effective diameter 2r, sheet thickness d, and ``plate modulus'' F, as a measure of elasticity, of the following form: FP·h2r=Σ lim k=1k=n1ck1·d2r+ck2(d2r)3,where the quotients F/p·h/2r and d/2r each are factors without dimensions.

This formula with only two terms (n=2) checks well with the data for our own test material as well as with other experimental results1 on diaphragms with pressure-proportional deflection. The probable relation of the separate terms of the formula to definite annular zones of the diaphragm as well as its applicability to diaphragms with other than pressure-proportional deflection are discussed.
Electronic Sequence Control Circuit for the Operation of a Wilson Cloud Chamber
Authors: Allen F. L.
Published: February 2005

A description is given of an electronic sequence control circuit for the operation of a Wilson cloud chamber used in cosmic-ray work. Necessary delays are introduced by unbalanced multivibrator circuits whose periods are adjustable by means of potentiometers. The circuit operating the magnetic-type valve makes use of two thyratrons, one to conduct the valve current and the second, to interrupt it, permitting large values of this valve current and therefore fast action. Minor modifications readily adapt the circuit to a chamber used in other investigations.
An Electric Field Meter for Use on Airplanes
Authors: Waddel R. C.
Published: February 2005

An instrument capable of measuring the magnitude and polarity of electric fields at selected regions on an airplane in flight is described. The device covers a range of from 5 volts per cm to 4000 volts per cm in four steps with linear scales and is powered from a 28-volt d.c. supply.
An Inverted Tetrode Voltmeter for High Negative Voltages
Authors: Schneeberger R. J.
Published: February 2005

If the normal functions of the grid and the plate of a conventional vacuum tube are interchanged, relatively large negative potentials applied to the plate can be measured as a function of the current drawn by one of the grids. By combining the characteristics of a tetrode operated in the inverted manner with a circuit employing a large amount of grid-cathode degeneration, an instrument possessing an exceptionally high degree of stability has been constructed which is capable of measuring negative potentials from zero to 30 kilovolts. The indication is nearly linear with voltage and the input impedance is of the order of 1013 ohms.
A Frequency Characteristic Analyzer
Authors: Sampsell J. W.
Published: February 2005

The frequency characteristics analyzer is a device for analyzing the frequency characteristics of filters, amplifiers, and other electronic elements whose pass bands are within the 500–50,000 cycle range.

While many frequency analyzers have been constructed, this is one of the first such analyzers in which (1) the width of the swept band and the rate of sweep can be varied independently, (2) the frequency is swept linearly, (3) the response of the pass band circuit can be positioned to appear at any point in the sweep, and (4) the oscillograph time base can be interlocked with the generator frequency.
The Production of Thin Be Foils
Authors: Bradner Hugh
Published: February 2005

A procedure for making Be foils between 10−5-cm and 10−3-cm thick, and with diameters up to an inch and a half, is described, and methods of mounting these foils are indicated.
Routine Use of Ionization Chamber Method for C14 Assay
Authors: Janney C. D. , Moyer B. J.
Published: February 2005

The design and routine use of apparatus for the measurement of amounts of C14 down to a specific activity of the order of 10−9 curie per gram is described. Use is made of an ionization chamber containing the sample to be analyzed (as CO2) and a Lindemann electrometer. The auxiliary electrometer circuits and the apparatus for handling the CO2 gas are also presented. The method is in regular use in the radiation laboratory for the routine analysis of samples obtained from biological tracer experiments. A comparison with other methods of C14 detection is included.
The Unbalance Squelcher
Authors: Tomiyasu K.
Published: February 2005

The transmission of unbalanced currents on shielded pair lines can be stopped by a double stub device called an unbalance squelcher. The unbalance squelcher, which is substantially a tandem bridge for unbalanced currents, reflects completely the unbalanced currents yet allows free passage of the balanced currents.
Dynamic Pressure Measurement by Optical Interference
Authors: Buck Willard E. , Barkas Walter H.
Published: February 2005

A pressure gauge is described in which the displacement of a pressure diaphragm is measured by recording photographically the motion of interference fringes formed by light reflected from the diaphragm and from an adjacent stationary mirror. The instrument is simple and unusually accurate and stable. Typical observed performance: frequency range, zero to over ten thousand c.p.s.; pressure range, zero to five thousand p.s.i.; absolute error, less than one-half percent. Calibration is carried out under static conditions and the response is linear. Presentation of the data is direct and the analysis of the records simple. Other broad fields of application of the new recording principle are indicated.
Improved Method for Measuring Hall Coefficients
Authors: Isenberg I. , Russell B. R. , Greene R. F.
Published: February 2005

The influence of the current electrodes on measurements of the Hall coefficient is examined. Equations are given for the ratio of the measured voltage as a function of the geometry of the sample. Experiments verifying these results are described. The conditions for maximum sensitivity are given.
A Voltage Integrator
Authors: Buzzell Anne , Sturtevant Julian M.
Published: February 2005

Integration, with respect to time, of a varying voltage is accomplished by counting the revolutions of the output shaft of a rate servomechanism. Accuracy of the order of ±0.1 percent over a 100-fold range of input voltage is obtained, with speed of response ample for many purposes.
A New Compact Tiselius Electrophoresis Apparatus
Authors: Moore Dan H. , White John U.
Published: February 2005

A compact Tiselius electrophoresis apparatus which incorporates the valuable features of the Tiselius method yet avoids its disadvantages of large size, costliness, and difficulty of operation is described. It incorporates a 2-ml capacity Tiselius cell, and a highly precise optical system based on Longsworth's scanning modification of the Toepler schlieren method. Two schlieren lenses provide parallel light through the cell and reduce the optic path length. The over-all dimensions of the self-contained unit are 63″×14″×12″.
A Device for Measuring Physiologic Pressure Phenomena Using the Bonded Electrical Wire Resistance Strain Gauge
Authors: Bierman Howard R.
Published: February 2005

An electrical device for measuring physiological pressure phenomena, using a resistance wire strain gauge, is described. The gauge is bonded securely to a metal diaphragm, deformation of which changes the resistance of the gauge, and causes a flow of current through an appropriate circuit. Examples of the applications in physiology of this device are presented along with typical recordings.
The Design and Construction of a Double-Focusing Beta-Ray Spectrometer
Authors: Kurie Franz N. D. , Osoba J. S. , Slack Lewis
Published: February 2005

For the measurement of beta- and gamma-ray energies one requires a magnetic spectrometer of high resolution and large solid angle. One of the simplest instruments satisfying these specifications is the double-focusing beta-ray spectrometer. The design and construction of such an instrument is described. This particular spectrometer has a mean radius of curvature for the electrons of 24.33 cm and preliminary measurements show that its resolution is about ⅓ percent and that about 0.2 percent of all the electrons of given energy which leave the source are focused on the counter. Construction of such an instrument proved to be very easy.
Reproducible Construction of Quartz Fiber Devices
Authors: Kirk Paul L. , Craig Roderick
Published: February 2005

Methods for construction of various types of quartz fiber structures by means of jigs also made from small quartz rod are described. It is shown that the advantages of jig construction are in obtaining a better product and particularly the ability to reproduce quite accurately a number of such quartz structures.

Various practical aspects of quartz fiber manipulation and construction are discussed.
Construction and Special Uses of Quartz Helix Balances
Authors: Kirk Paul L. , Schaffer F. L.
Published: February 2005

Technique is described for the construction of uniform smooth quartz helix balances of any desired sensitivity or load capacity by mechanical means. Some of the less common but highly desirable uses of such balances are listed.
High Energy Neutron Detector
Authors: Wiegand Clyde
Published: February 2005

A neutron detector which utilizes the fission of bismuth and responds only to neutrons of energy greater than about 50 Mev is described. The efficiency is low (about 10−6), but the instrument is suitable for monitoring a high energy neutron beam and for beam attenuation measurements.
A Time Interval and Reference Line Marker for Moving Film Photography of Oscilloscope Traces
Authors: Kammer E. W.
Published: February 2005

A device is described which produces a reference light beam capable of being modulated at any desired frequency up to several thousand cycles per second. The light source can be mounted on the face of most oscilloscopes with slight alterations. It facilitates the introduction of a timing scale and fixed reference line when photographic recordings are made of oscilloscope traces by means of drum or continuously moving film cameras.
An Electronic Integrating Circuit for Recording the Spontaneous Activity of Animals
Authors: Campbell C. J. , McLean R. A.
Published: February 2005

Various mechanical and electrical techniques have been used to record the spontaneous activity of animals during pharmacological and physiological studies. Most of them are in-adequate in one way or another. An electronic integrating circuit is described which eliminates the principal faults inherent in other methods. An electromagnetic pick-up is mounted on a small rigid cage which is supported on a viscous damping mount. The output of this pick-up is amplified, rectified, and stored in a condenser. The voltage acquired by the condenser is applied as the plate voltage of a small thyratron. The bias on the thyratron controls the energy required to fire the circuit. When the circuit fires, a sensitive relay is closed and the unit represented is written on a moving tape and added to a counter. The results obtained by this method are in discrete units and can be treated by mathematical methods.
An Autographic Stress Relaxometer
Authors: Stein Richard S. , Schaevitz Herman
Published: February 2005

An autographic stress relaxometer has been designed and constructed for studying the relaxation of the stress of a polymer film elongated to constant length. The force-measuring element is a linear variable differential transformer which measures the distortion of a flexible steel ring and drives a recorder. The sample is elongated to the desired length automatically, and the correct length is maintained by means of a second differential transformer.
Optical Measurements of Surface Films. I
Authors: Rothen Alexandre , Hanson Marjorie
Published: February 2005

Practical information is given concerning the calibration of an instrument called the ellipsometer, which is used to measure thicknesses from one angstrom unit up to many thousands angstrom units of transparent films deposited on polished metal slides. The instrument is a half-shadow instrument taking advantage of the ellipticity of polarized light reflected from film-coated metallic surfaces. The half-shadow is produced by depositing a different thickness of transparent material on the lower and upper part of the slides, or by evaporating directly on the lower part of chromium slides a thin layer of gold.
A Microwave Gas Discharge Counter for the Detection of Ionizing Radiation
Authors: Brown Sanborn C. , McCarthy John J.
Published: February 2005

Characteristics of a gamma-ray counter making use of a 3000-megacycle gas discharge in a coaxial mode cavity resonator are described. The breakdown of a discharge in gases at these frequencies does not depend upon secondary effects. Since the breakdown is not controlled by positive ions, shorter breakdown and resolving times than those of a Geiger-Müller counter are realized. In the high frequency discharge, ambipolar diffusion is the controlling factor in loss of electrons. A d.c. clearing field is superimposed on the a.c. field to eliminate electrons rapidly. A quenching agent is present to suppress electron emission from positive ion bombardment of the walls. The discharge is extinguished by reducing the magnetron power electronically. The plateau and sensitivity characteristics are similar to those of a Geiger-Müller counter.
An X-Ray Diffraction Photometer
Authors: Christ C. L. , Champaygne E. F. , Barnes R. Bowling , Salzman C. F.
Published: February 2005

An automatic recording instrument which permits the direct comparison of the x-ray diffraction patterns of two separate powder samples has been constructed through suitable modification of a commercial North American Philips Geiger counter x-ray diffraction spectrometer. Some of the experimental results obtained with the new instrument are shown, and possible applications to qualitative and quantitative analysis indicated.
A Technique for the Making and Mounting of Fine Mesh Screens
Authors: Law H. B.
Published: February 2005

A new process has been developed for making fine mesh metal screens from glass masters. The master contains grooves corresponding to the screen wires. Metal is sputtered on the master, rubbed off the surface and the remaining metal in the grooves plated to form the screen. Screens from 200 to 1500 meshes per inch have been made with better than 50 percent transmission.

A method of mounting the screens on a ring and subsequent tightening by heat treatment is described.
A Study of Small Ether-Argon Geiger-Müller Counters
Authors: Robinson C. V. , Peterson R. E.
Published: February 2005

A variety of ether-argon mixtures were tried in counters with cathodes ranging in diameter from 0.268″ to 0.038″ and with wires ranging in diameter from 2.3 mils to 0.5 mil. The results suggest an optimum relationship between cathode diameter, wire size, and mixture. Good characteristics were obtained with cathodes as small as 0.067″ in diameter. Small probing counters designed on the basis of this relationship are described.
Measurement of the Electron Current in a 22-Mev Betatron
Authors: Bess Leon , Hanson A. O.
Published: February 2005

The magnitude of the charge circulating in a betatron orbit is determined from its magnetic effect. The results indicate that the charge accelerated to high energy per second, in a 22-Mev betatron operating at 180 cycles per second, corresponds to an average current of about 0.15 microampere.