bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of a 100-Kilogauss 4-Inch Core Solenoid for Continuous Operation
Authors: Giauque W. F. , Lyon D. N.
Published: February 2005

The design of high field cylindrical solenoid magnets for continuous operation is discussed. Equations are given relating power input, allowable temperature rise, coolant rate, and pressure drop to give the detailed dimensions required for the electrical conductor and the cooling annuli. The stresses from electromagnetic forces acting upon conductors are discussed, equations are given, and some devices and factors concerned in resisting these forces are described. The properties of kerosene as a magnet coolant and safety precautions for its use are discussed. The details for a magnet with a 4-in. air core, constructed for good homogeneity, and 7.5 megawatts of power are given. A procedure for preparing laminated insulation in the form of a spiral is described and a method of squaring the magnet ends to improve heat transfer, reduce heat production, and facilitate support at the ends has been devised. Equations are given which enable the evaluation of the conductor temperature at any point along the coil by making use of the temperature coefficient of resistance for thermometric purposes. A graph of conductor and kerosene temperatures as a function of axial length has been prepared from data obtained from magnet operation. The particular magnet described here, which is the first of several to be built, gave a field of 99 500 gauss at 7.5 megawatts. Some suggested improvements based on experience with the present magnet have been included.
Susceptibility Servo-Balance for Measurements on Metals of Extremely Low Resistivities
Authors: Hedgcock F. T. , Muir W. B.
Published: February 2005

Although a great variety of methods have already been described for measuring magnetic susceptibility, the present instrument has the advantage that it makes possible measurements on weakly magnetic high-purity metals having extremely small resistivities. Most servo-balances for measuring susceptibility that have been described in the literature have been for strong paramagnetics or ferromagnetics and in none of the balances has the effect due to strong induced eddy currents been allowed for. The present instrument consists of a sensitive electrodynamic balance which is operated as a null instrument by allowing it to form part of a servomechanical network. The feedback system provides a stiffness of balance movement of 8×104 d/deg deflection. The sensitivity of this instrument is such that changes of 10−9 emu/g may be detected in the susceptibility of large metallic samples having electrical resistances less than 10−9 ohm cm.
Unidirectional Integrating Mechanism for the Buerger Precession Camera
Authors: Lingafelter E. C. , Stewart J. M.
Published: February 2005

The construction of a unidirectional integrating precession camera is described. The camera is a modification of a Buerger-Supper precession camera. It is designed to be used in conjunction with an integrating microphotometer. The instrument has been used to gather zero-level data. Its reliability has been tested by measuring the intensity of the diffracted beams from a single crystal of sodium chloride. The results of the test show good agreement between single crystal data from the precession method and powder data from a spectrometer.
New Reflection Oximeter
Authors: Polanyi M. L. , Hehir R. M.
Published: February 2005

It is experimentally shown that the ratio of light reflected by a nonhemolysed blood sample at two suitable wavelengths is a linear function of the oxygen saturation. A simple instrument to determine oxygen saturation in vitro, based on these findings, is described.
Transient Analysis of the White Cathode Follower
Authors: Brown Melvin
Published: February 2005

The White cathode follower is a two-tube series device that provides output impedances of the order of 5 ohms and transmits pulses of either polarity with minimal distortion. A dc and transient analysis of the White cathode follower is made, and a typical circuit is analyzed. The effect on the transient response of varying the circuit parameters is discussed. Throughout the paper the White cathode follower is compared to the well-known conventional cathode follower. The White cathode follower may have an advantage in gain-bandwidth over the conventional cathode follower by a factor of five.
Accurate Microwave Wavemeters with Convenient Calibration Tables
Authors: Bussey H. E. , Estin A. J.
Published: February 2005

Accurate and convenient microwave cavity wavemeters are described that are suitable for many precise physical measurements. High Q's were attained by refined construction techniques. At 9000 Mc a precision of 0.02 Mc was obtained. The absolute accuracy also may be very high after strains in the metal have stabilized. A calibration table containing 104 entries, easily formed by means of a high speed computer, makes the wavemeters convenient to use. The curve fitting method, accurate to one in 106, is described.
Optical Cell for the Observation of Raman Scattering in Gases at High Pressures
Authors: Stryland J. C. , May A. D.
Published: February 2005

For Raman spectroscopy of gases, intense illumination is required. The relatively low tensile strength of transparent materials has always severely limited such studies at high pressures. This paper describes a method by which use is made of the very high compressional strength of glass. The essence of the method is that the compressed gas is contained in an enclosed space outside a thick-walled glass tube; inside the tube a water-cooled mercury lamp is inserted. Pyrex tubes of 0.5 in. i.d. and 0.75 in. o.d. thus withstand pressures in excess of 3000 atm. The scattered light is observed through a conventional self-sealing window. High resolution Raman spectra have been obtained, for various simple gases, at pressures up to 2500 atm.
High Field Solenoid Magnet with Liquid Nitrogen Cooling
Authors: Adair T. W. , Squire C. F. , Utley H. B.
Published: February 2005

The high field solenoid described in this paper operates at liquid nitrogen temperature (78°K), and uses a relatively small dc power source (100 kw). It has operated continuously and steadily at 36 kgauss and 62 kw under steady state conditions. This is done by forcing the liquid nitrogen coolant through the annuli between the electrical conductors with a circulation pump. The first magnet designed has a 4.6-cm diam core and the length is such that the central portion of the solenoid gives an experimental ``working space'' 10 cm in length where the field is quite uniform. The cost is modest compared to comparable water-cooled solenoids both as to initial investment and operation.
Nondestructive Measuring Method of Polarization for the Study of Ferroelectrics
Authors: Husimi K. , Kataoka K.
Published: February 2005

The piezoelectric output voltage of a ferroelectric crystal in an ultrasonic field is determined by its state of polarization. By using this property, a technique has been developed for the measurement of polarization without disturbing the domain configuration. This ultrasonic method has several advantages over the Sawyer-Tower method and Chynoweth's pyroelectric method. Quasi-static hysteresis measurements of a barium titanate single crystal have been carried out to illustrate the method.
High Temperature Microscope Stage
Authors: Sundquist B. E.
Published: February 2005

A microscope stage has been designed and constructed that permits microscopic observation of small particle specimens in the temperature range from room temperature to about 1200°C. Higher temperatures can be obtained with minor changes.

The constructed stage contains four independent furnaces designed to permit accurate observation and control of specimen temperature even under conditions of rapid heating or cooling. Specimens are heated in easily inter-changeable quartz crucibles by a Nichrome foil resistance wrapped on a small Alundum refractory tube.
Simple Null-Indicating Saturable-Core Magnetometer for the Detection of Static Magnetic Fields
Authors: McCurley E. P. , Blake C.
Published: February 2005

A simple null-indicating saturable-core magnetometer has been designed as a completely self-contained unit requiring no associated equipment other than a VTVM or oscilloscope for monitoring the output. The device is useful for detecting static magnetic fields of the order of 0.1 millioersted. It was built to enable the establishment of a near zero magnetic field over a limited volume by means of pairs of Helmholtz coils. A Hartshorn bridge circuit is employed to cancel out the fundamental of the driving frequency in the output portion of the circuit. A test signal incorporated into the instrument affords a check on the sensitivity.
Techniques for Measuring the Infrared Absorption Spectra of Fused Salts
Authors: Greenberg Jacob , Hallgren Leander J.
Published: February 2005

The infrared absorption spectra of NaNO2 and LiNO3 in both the solid and liquid phase have been obtained by two methods. In one case the salt is supported in the interstices of a fine mesh platinum screen, and in the other case the measurements were made in a reflectance cell.
Pulse Size from Neutrons of 0.14 to 2.3 Mev in Plastic Scintillator
Authors: Gettner M. , Selove W.
Published: February 2005

The light output of a sample of plastic scintillator for proton recoils from neutrons of energy 0.14 to 2.3 Mev has been measured. Recoil protons of 1-Mev energy give about ⅕ the light from 1-Mev electrons; protons of 0.2 Mev give about ⅛ the light from 0.2-Mev electrons.
Recalibration of the NBS Carbon-14 Standard by Geiger-Müller and Proportional Gas Counting
Authors: Mann W. B. , Seliger H. H. , Marlow W. F. , Medlock R. W.
Published: February 2005

Compensated internal gas counters have been constructed for the recalibration of the National Bureau of Standards carbon-14 solution standards. Satisfactory agreement has been obtained by counting in both the proportional and Geiger regions.
A New Method for the Measurement of Cathode Interface Impedance
Authors: Tamiya J.
Published: February 2005

A new simple and sensitive bridge method for the measurement of cathode interface impedance is reported in this paper. A tube with an interface impedance under test in this method forms a bridge together with a reference tube with no interface layer and with an external variable RC circuit in its cathode return. The bridge is excited by a set of three sinusoidal signals of 200 kc, 1.1 and 5 Mc. The unknown interface impedance is then measured by simultaneously balancing the bridge for these frequencies. The detector consists of amplifiers tuned to each frequency and a cathode-ray oscilloscope that displays each signal separately. A small wobbling of the transconductance in the reference tube is also provided for simplifying the measurement and overcoming drift of tube characteristics. This bridge has a sensitivity of the order of 0.002 rad as a minimum detectable phase shift, and allows a measurement of interface resistances as low as a few ohms with time constants of 0.01 μsec or more, even in ordinary tubes.
Closed Circuit Liquid Hydrogen Refrigeration System
Authors: Chelton D. B. , Dean J. W. , Birmingham B. W.
Published: February 2005

A liquid hydrogen bubble chamber has been maintained at 27°K with an automatically controlled closed circuit hydrogen refrigeration system of 300-w capacity. The system has been used continuously for more than 2000 hours on the 15-in. bubble chamber at the Lawrence Radiation Laboratory, University of California, Berkeley, California. The design uses commercially available heat exchanger tubing and controls. Actual performance is compared to predicted performance for design operating conditions. The refrigeration system is sufficiently flexible to be used on other experimental apparatus requiring refrigeration at liquid hydrogen temperatures.
High Sensitivity Mass Spectrometer Leak Detector
Authors: Daly N. R.
Published: February 2005

A new type of mass spectrometer ion detector is described and some of its applications discussed. A positive ion entering the detector is accelerated onto a thin metal foil where it releases secondary electrons, which are in turn accelerated onto an organic scintillator viewed by a photomultiplier; this measures the total ion beam. Those ions which penetrate the foil sufficiently release secondary electrons from the back of the foil, and these are detected in a similar way. The transmission properties for many light ions has been investigated and it has been found that the foils have high transmission for helium ions and high rejection for ``air'' ions. The results obtained can be applied toim proving the sensititivity of leak detectors, appearance potential measurements, and the analysis of small quantities of deuterium in hydrogen.
Analysis of Gas Evolution from a Titanium Hydride Gas Generator
Authors: Levine Leonard , Lichtman David
Published: February 2005

Gas analysis on a metal bakable high vacuum system is carried out with the aid of an omegatron mass spectrometer to determine the purity of hydrogen evolved from a titanium hydride source. Curves of the ion current versus mass-to-charge ratio are shown for the system, before, during, and after bakeout as well as during the running of the generator. The generator, after moderate processing, is found to yield hydrogen gas that is 97% pure. The impurities found are water vapor, methane, and ethane. An explanation for the presence of these impurities is offered.
Low Frequency Wave Filters Employing Thermistors
Authors: Rasmussen Robert A.
Published: February 2005

A review of the general properties of thermistors and analyses of their small signal characteristics are presented. Measurements of their ac properties and response curves obtained for the simplest filter circuit configurations are then described and the results analyzed.
High Speed Scalers using Tunnel Diodes
Authors: Spiegel Philip
Published: February 2005

A solid-state scaler circuit has been developed with a double pulse resolution of less than 50 nsec. It utilizes the characteristic of series-connected tunnel diodes wherein voltage is a multi-valued function of current. The decade scaler described in this paper requires very little power, may be microminiaturized, and is potentially more economical and easier to fabricate than contemporary scalers.
Large Area Germanium Surface-Barrier Counters
Authors: Walter F. J. , Dabbs J. W. T. , Roberts L. D.
Published: February 2005

A description is given of a solid-state counter of good resolution, long term stability, and fast rise time which is suitable for heavy charged particles, for example, alpha particles and fission fragments. A simple theoretical model for the counter behavior is presented which is found to describe the observed behavior of the counter very well. The importance of germanium purity in connection with pulse height, rise time, and counter area is discussed. Counters with sensitive areas up to 5 cm2 have been successfully used.
Computer for the Identification of Charged Particles
Authors: Stokes Richard H.
Published: February 2005

An improved computer circuit is described which can be used with appropriate counters to identify charged particles. Previously this system has been used to identify protons, deuterons, and tritons. More recently the computer has been used to separate He3 and He4 events. A sample calculation of the performance is given which shows that He3 and He4 events can be distinguished over a wide energy range with a single choice of computer parameters. Consideration is also given to the use of the method for low energy particles. It is concluded that, with easily attainable counter resolution, protons can be identified at energies extending below 1 Mev.
Evaporation Rate Monitor
Authors: Giedd G. R. , Perkins M. H.
Published: February 2005

A method for controlling the deposition rate of vacuum deposited films is described. This paper presents details of the rate sensing device and furnace control system. The control system utilizes a saturable-core reactor driven by the output of the rate monitor. This controls the furnace current, thus completing the system. Operation and calibration of the control system is described and experimental results are tabulated.
Variable Energy Spiral Ridge Cyclotron
Authors: Allen James S. , Chatterjee Santimay , Ernest Loren E. , Yavin Avivi I.
Published: February 2005

A spiral ridge cyclotron which can accelerate protons from 3.5 to 15 Mev, deuterons from 7 to 14 Mev, He3++ from 11 to 37 Mev, and alpha particles from 15 to 27 Mev is described. The required magnetic field is obtained from four spiral shims and five correction coils placed on each of the pole faces of the magnet. The spiral shims produce a maximum rms flutter of 0.07 which provides sufficient vertical focusing beyond a radial distance 6 in. from the center of the cyclotron. The two innermost correction coils provide magnetic focusing up to 6 in. and the three outer coils build up the isochronous field. Focusing effects of slits, placed on the dee and the dummy dee in the path of the particles for the first four revolutions, are demonstrated. The machine can deliver 1 ma of proton beam at the extraction radius, 18.5 in.
Measurement of Small Differences in the Second Virial Coefficient of Gases at Temperature below 0°C
Authors: Thomaes G. , Van Steenwinkel R.
Published: February 2005

An apparatus is described which allows measurements of small differences of the second virial coefficient between two gases at low temperatures (90° to 300°K).
Null-Point Torsion Effusion Apparatus
Authors: Rosen Charles L.
Published: February 2005

A null-point apparatus, capable of manual or automatic operation, for determining vapor pressures by the torsion effusion method is described. Vapor pressure measurements in the range 10−6 to 10−2 mm Hg can be determined with an accuracy of ±1%. The sensitivity is constant over the entire pressure range and is influenced only by the choice of a suitable torsion wire.
Simple High-Resolution Nuclear Resonance Spectrometer
Authors: Keuning R.
Published: February 2005

A description is given of a nuclear magnetic resonance spectrometer, using a permanent magnet and very simple electronic circuits. A resolving power of better than one part in 108 is obtained with samples of approximately 4.5 mm in diameter, while stability and signal-to-noise ratio are satisfactory.
Induction Apparatus for the Continuous Measurement of Magnetic Susceptibility
Authors: Norder Wallace A.
Published: February 2005

An induction apparatus is described for measurement of the paramagnetic susceptibility of metals during exposure to gases, specifically hydrogen. Provision is made for heating to 500°C and for removal or addition of gas during measurement. The device may be adapted for use at low temperatures.
Response Spectra for Gamma Rays in CsI
Authors: Miller W. F. , Snow William J.
Published: February 2005

Response spectra for gamma rays incident on cesium iodide (thallium-activated) crystals have been calculated for two crystals. The crystals considered are right circular cylinders and the gamma-ray energies are 0.661, 1.83, 2.76, and 3.13 Mev. Comparisons between the response spectra for CsI(Tl) and NaI(Tl) crystals of the same size are presented.
The Magnetic Deflector of the Buenos Aires 180-cm Synchrocyclotron Beam
Authors: Rosenblatt J. , Slobodrian R. J.
Published: February 2005

The magnetic deflector system of the Buenos Aires 180-cm synchrocyclotron beam consists of a regenerator (previously reported) and a critical magnetic channel. The channel was built starting on the maximum of the radial oscillation and following a trajectory given by ρ=83.5+10α11/4 (in cm), where (ρ,α) are polar coordinates with origin at the center of the machine and α is measured from the maximum of the radial oscillation. Alternating gradient magnetic fields were used in order to keep the beam parallel up to the magnetic quadrupoles. Thus the vertical divergence of the beam is vanishingly small and the radial divergence is 1/200. With the complete assembly in place 20% of the circulating beam is thrown by the regenerator into the magnetic channel, and its transmission is 10%. The over-all extraction efficiency is therefore 2%.
Production of a Uniform Magnetic Field by Means of an End-Corrected Solenoid
Authors: Gardner M. E. , Jungerman J. A. , Lichtenstein P. G. , Patten C. G.
Published: February 2005

Calculations and experimental technique used in producing a uniform magnetic field with an end-corrected solenoid are discussed. The field was trimmed to be uniform to 0.01% in an axial region comprising 63% of the solenoid at a maximum field strength of 480 gauss.
Recording rf Spectrometer for Nuclear Quadrupole Zeeman Spectra
Authors: Dean C.
Published: February 2005

A semi-automatic recording spectrometer system finds the loci of magnetic field orientations, relative to a single crystal sample, for which an unsplit component occurs in the Zeeman spectrum of chlorine nuclear quadrupole resonances from the sample. The system operates continuously without attention, except for approximately daily resetting, for up to several weeks to obtain the data for crystals with weak spectra. Circuit diagrams are given for the system components, and the analysis of the data is discussed.
Mechanical Spectrograph Shutter for Extremely Short Exposure Times
Authors: Wiese Wolfgang L.
Published: February 2005

A mechanical spectrograph shutter for exposure times down to 5×10=8 sec with a system for synchronization is described and its performance discussed. In contrast to Kerr-cell shutters most of the incident light is transmitted, which is of considerable importance in extending the range of photographic spectroscopy to studies of very brief transients.
Evaporation Source with Controlled Characteristics
Authors: DaSilva Edward M.
Published: February 2005

Reproducible and constant evaporation rates can be realized when an evaporant is heated by radiation. This article describes a basic source structure with the controlled characteristics necessary for reproducible thin film techniques. Particular attention to the simplicity of design and application has provided an easily constructed practical source.
Simple Technique for the Automatic Recording of Monolayer Compression Characteristics
Authors: Mann J. Adin , Hansen Robert S.
Published: February 2005

Trurnit and Lauer [Rev. Sci. Instr. 30, 975 (1959)] have recently described an automatic recording film balance system suitable for automatic recording of many properties of insoluble surface films. The authors have been working with an instrument similar in principle, somewhat less versatile, but very simply constructed by modifying a Cenco hydrophil balance. It is well suited for automatic recording of force-area curves for monolayers spread on aqueous substrates. Major components include a linear differential transformer, lead screw barrier advance system, and an x-y recorder. The practicality of the appratus was demonstrated on a stearic acid monolayer spread from benzene on a distilled water substrate. Sensitivity of 0.01 d/cm in spreading pressure and 0.1 A2 in molecular co-area was readily obtained, together with a surface pressure range of 0–60 d/cm.
Double Resonance Technique for the Elimination of Proton Spin-Spin Splitting in High Resolution PMR Spectra
Authors: Kaiser Reinhold
Published: February 2005

The double resonance technique aims at removing the effect of spin-spin coupling by the application of a strong rf field at the resonance frequency of the disturbing nucleus in addition to the weak rf field used for observation of the NMR spectrum. A method is described whereby the weak rf field is obtained by a small audio frequency modulation of the magnetic field strength. This method is applicable to chemically nonequivalent groups of hydrogen nuclei to simplify the interpretation of high resolution proton magnetic resonance spectra. Two examples are given.
Displacement-Type He II Heat Switch
Authors: Shore Ferdinand J.
Published: February 2005

The operation of a heat switch is described in which the conducting substance is liquid He II and in which the nonconducting state is achieved by displacing the He II with a poor conductor, e.g., Teflon. The switch is well suited for use in the first stage of a magnetic refrigerator operating with a bath temperature near 1°K. At this temperature it performs better than a lead superconducting switch.
Use of Graphite as Low Temperature Support and Shunt for Heat Switch
Authors: Shore F. J. , Sailor V. L. , Marshak H. , Reynolds C. A.
Published: February 2005

Artificial pitch-bonded graphite is known to exhibit an extremely large variation of heat conductivity with temperature. It is both rigid and strong, and below 1°K its heat conductivity is exceptionally small. For these reasons we have found it to be an ideal support material for use within the adiabatic enclosure of a cryostat operated below 1°K. Furthermore, above liquid nitrogen temperature graphite is an excellent heat conductor, and when used in parallel with a lead heat switch, it proves unnecessary to admit exchange gas during the precool period. The graphite exhibits a strong pumping action for helium gas at low temperatures.
Six-Meter Radius Bent-Crystal Spectrograph for Nuclear Gamma Rays
Authors: Kazi A. H. , Rasmussen N. C. , Mark Hans
Published: February 2005

A six-meter radius bent-crystal spectrograph for the precision measurement of nuclear gamma-ray wavelengths has been designed, constructed, and placed into operation at the Massachusetts Institute of Technology. This instrument is particularly well suited for directly measuring neutron capture gamma rays produced by samples placed in the through port of the MIT research reactor. The spectrograph is designed to measure wavelengths of gamma rays in the energy region from 0.1 to 4.0 Mev with an estimated precision that varies from about 0.01% at 0.1 Mev to 0.3% at 4 Mev. Photographic methods are used to record the gamma-ray lines on the focal circle. A bent crystal is used to diffract and focus the gamma rays. Line width and efficiency data have been obtained for the (310), (003), and (006) planes of quartz. The efficiency of the instrument is quite low. In order to record a line at 2.0 Mev an exposure time of about 6000 curie hours is required.
Intracardiac Catheter Tip Piezoresistive Pressure Gauge
Authors: Traite Max , Welkowitz Walter , Downs Rudolph
Published: February 2005

A pressure gauge is described that can be encased in a small-bore plastic cathether. The small size permits insertion directly into the heart. The unit uses a two-section piezoresistive element, operated as a cantilever. The sensitivity of the gauge is 0.16 mv/v/psi, and the frequency response is flat from 0 to 400 cps.
Arrangement for Electrochemical Potential-Time Measurements in the Millimicrosecond Range
Authors: Blomgren E. , Inman D. , Bockris J. O'M.
Published: February 2005

An arrangement is described which allows potential-time measurements in galvanostatic pulse techniques to be performed 40–80 mμsec after initiation of the pulse.
Ion Transport High Voltage Generators
Authors: Stuetzer Otmar M.
Published: February 2005

Ions are injected into an insulating liquid and pumped into a collector, which assumes a high potential. Results of a theoretical treatment of this arrangement are compared with experimental evidence. While the generator has low energy conversion efficiency, it possesses a number of compensating advantages.
Temperature Measurement Based on the Viscous Flow of Gas in a Wheatstone-Bridge Network
Authors: Hoge Harold J.
Published: February 2005

A Wheatstone-bridge arrangement of capillary tubes carrying a flow of inert gas is described, with which the resistance to flow of a capillary tube serving as a thermometer may be measured. The resistance is shown to be proportional to the product Tη, for constant mass rates of flow in the viscous regime. Gas-viscosity thermometers have relatively open and linear scales, and are usable over wide temperature ranges. With helium gas, for example, the product Tη varies strongly and smoothly with temperature from below 1° to above 1500°K and probably much farther. Experimental tests of Al2O3 capillary thermometers in a high temperature furnace are reported. Some of the thermometers were reasonably stable at 1788°K.
Comparison of the Sensitivities of the Beam Maser and Cavity Absorption Spectrometers
Authors: Beers Yardley
Published: February 2005

A formula for the signal-to-noise ratio of a maser spectrometer is derived by considering it as a special case of a cavity spectrometer. This formula is consistent with evaluations made by previous authors but is more convenient for comparison with an absorption cavity spectrometer. In applications where high resolution is not a requirement, the pressure and power level in an absorption spectrometer may be made very large so that its sensitivity can be superior to that of the maser. However, if it is operated to obtain the highest possible resolution, its sensitivity may or may not be superior to that of the maser, depending upon the frequency and upon other conditions. In the situation of greatest interest, in which the linear dimensions of the cavity are scaled in proportion to the wavelength and in which it is sufficiently large to make the effect of collisions between the molecules and the walls negligible, it is shown that the sensitivity of the maser relative to the absorption spectrometer varies inversely with the frequency. The theory is illustrated by calculations pertaining to spectrometers designed for the ND3 inversion spectrum at 1500 Mc. From these calculations it can be inferred that, with the best available techniques, the two instruments would have about equal sensitivity in the region of 1500 to 2000 Mc, while at lower frequencies the maser would have higher sensitivity and the absorption spectrometer would have higher sensitivity at higher frequencies.
Notes on a High Pressure Gas Apparatus
Authors: Langer D. , Warschauer D. M.
Published: February 2005

A hydrostatic high pressure apparatus capable of achieving 18 kilobars at room temperature, 14.1 kilobars at 77°K, and limited in pressure at lower temperatures only by the freezing of helium is described. A number of techniques facilitating construction, operation, and repair are described. An experimental pressure vessel and cryostat for optical studies to 16 kilobars in the temperature range from 370° to approximately 60°K are also discussed.
Visual Signal Generator
Authors: Kelly D. H.
Published: February 2005

A device is described which generates sinusoidal waves of radiant power for use in visual experiments. The instrument covers a continuous range of frequencies from 2 to 75 cps, modulation amplitudes from 0.001 to 1.0, and luminance levels from 0.01 to 1500 mL. Frequency, amplitude, and luminance controls are mutually independent. Both ``equal-energy'' white light and narrow-band chromatic stimuli are provided.
System for Oscillographic Recording of Selected Pulses from a Series of Randomly Arriving Impulses
Authors: Trorey A. W.
Published: February 2005

When velocity logging oil wells, a sonde is raised from the bottom of the well borehole at a slow, but variable and unpredictable rate. This sonde transmits pulsed acoustic energy at a variable pulse repetition rate into the earth surrounding the borehole and, in addition, detects the refracted acoustic pulses after they have traveled a few feet through the earth surrounding the borehole. In order to ascertain certain characteristics of the earth, it is desirable to record photographically those pulses occurring, not at specified time intervals, but at specified depth intervals. This is accomplished by converting the sonde depth to electrical gate pulses occurring at the desired depth intervals. These gate pulses are used to open a gate which permits only the first acoustic pulse following a gate pulse to pass through the gate and be photographed on a triggered oscilloscope. The equipment is fully automatic in that the camera film is automatically advanced between recorded pulses and precautions are automatically taken to prevent double exposures. Similar instrumentation should be applicable to related problems involving the photographing of system responses as a function of some measurable parameter which varies slowly but unpredictably with time.
Sensitive Output Indicator for Differential Transformer Displacement Determinations
Authors: Wobschall Darold
Published: February 2005

A transistorized circuit particularly designed as an output indicator for linear variable differential transformers is given. It is relatively simple to construct, adjust, and operate. The advantages of a phase-sensitive detector for the measurements of small displacements is discussed. Resolution of the unit is about 0.05 μ; the linearity is about ¼%.
Lithium Ion Sources
Authors: Allison Samuel K. , Kamegai M.
Published: February 2005

The preparation of artificial β-eucryptite (Li2O Al2O3 2SiO2) as a filament coating for the emission of Li+ ions is discussed. Two ion sources with their initial focusing gaps are described.
Automatic Conductivity Plotting Machine
Authors: Tiemann J. J.
Published: February 2005

A system diagram and the circuit for each of the components of an automatic conductance plotting machine are presented. Conventional circuitry using vacuum tubes is used throughout. The circuit impresses a small 5-kc incremental voltage of controlled amplitude upon the dc bias of the diode under test and senses the magnitude and sign of the in-phase component of the resulting current.
Transmission Current Monitor for High Energy Electron Beams
Authors: Taimuty S. I. , Deaver B. S.
Published: February 2005

A current monitor suitable for use with continuous or pulsed high energy electron beams is described. It functions by collecting slow secondary electrons emitted on passage of high energy electrons through a thin foil in vacuum. The secondary current is a linear function of primary current at average primary currents up to at least 120 μa (peak current density −150 ma/cm2), and is independent of energy at least in the range 6–30 Mev. With design modifications, the device should be capable of monitoring current at energies as low as 1 Mev with negligible beam absorption.
Substitution Method of Measuring Standing Wave Ratio
Authors: Nunn W. M.
Published: February 2005

A general set of standing wave relations, applicable to the rf- and i.f.-substitution techniques, are derived and used in the subsequent development of curves appropriate to measurements made around the pattern minimum. Although the experimental results using the rf-substitution procedure have not been recorded for a VSWR in excess of 200:1, there appears to be no limit on the magnitude of standing wave ratio that can be measured, if suitable equipment is available. An analysis of errors reveals that the principal factor which influences the accuracy attainable is the precision with which the attenuator can be determined.
Transfer of Heat Below 0.15°K
Authors: Anderson A. C. , Salinger G. L. , Wheatley J. C.
Published: February 2005

The transfer of electrically-supplied heat from a copper thermal link into single-crystal slabs of chromium potassium alum has been measured in the temperature range from 0.03 to 0.15°K. Temperature differences produced by heating were less than 6% of the average temperature. The heat transfer rate per unit temperature difference is characteristic of two thermal conductances in series with a heat sink. One of the conductances is characteristic of electrical-purity copper and is ascribed to the copper thermal link. The second corresponds to a heat transfer rate per unit temperature difference and per unit contact area of 3×105 T3 erg/sec cm2 K°4. Comparison with other experiments leads to the conclusion that heat flow rates into single crystals of ferric alum and chrome alum are proportional to the contact area with the thermal link and are reasonably reproducible from experiment to experiment. In the present experiments it is likely that classical thermal diffusion does not determine the flow of heat within the alum crystals. Instead, the experiments suggest that the T3 thermal conductance is a boundary effect and that the phonon mean free path within the chrome alum crystals is sufficiently long to insure that the crystal temperature is homogeneous.
500-kw Pulse Modulator for Accelerator Applications
Authors: Wheeler George W.
Published: February 2005

A pulse modulator has been designed for use with the rf system of the Yale heavy ion accelerator. This unit combines the desirable features of a hydrogen thyratron with the versatility of a hard tube in a system of relatively low cost. The pulse has a rise time less than 1 μsec and a duration which is variable up to 3.5 msec. A pulse of 8.5 kv at 60 amp can be obtained with a duty cycle of 3.5%.
Liquid Helium Scintillation Counter as a Neutron Polarimeter
Authors: Simmons J. E. , Perkins R. B.
Published: February 2005

A liquid helium scintillation counter has been constructed and used in analyzing the spin polarization of neutrons in the range of energy near 20 Mev. Details of construction and operation of the device are described. The glass scintillation flask contains 8 moles of helium, and is supplied by a reservoir which provides 7 hours continuous operation under experimental conditions. The pulse-height spread for a source of natural alpha particles is approximately 25%. It is found that the attenuation of the helium scintillation light in the liquid is not appreciable at a distance of 10 cm, while the wavelength is observed to be less than 1600 A. Consequently, use of a fluorescent material as a wave shifter within the helium flask is required. The intensity of the wave shifted helium light compares favorably with that from CsI(Tl). The helium counter is used in coincidence operation with a plastic scintillator neutron detector. Under these circumstances, the width of a gated helium recoil pulse-height distribution is generally less than 30%. The geometry and electronics for a typical neutron polarization experiment are described.
Pulsed X-Band EPR Spectrometer
Authors: Kaplan D. E. , Browne M. E. , Cowen J. A.
Published: February 2005

A pulsed X-band electron paramagnetic resonance spectrometer suitable for observing spin echoes in the sub-microsecond time domain has been designed and operated. Cryogenic apparatus makes possible measurements in the 300−1.6°K temperature range. System design considerations are discussed and circuit schematics are presented. Results of measurements of the spin-lattice relaxation time T1 and the spin-spin relaxation time T2 are reported for several paramagnetic substances. Application of such instrumentation to information storage is discussed.
Use of an Operational Amplifier with Helmholtz Coils for Reducing ac Induced Magnetic Fields
Authors: Marzetta Louis A.
Published: February 2005

A feedback system is described for canceling magnetic fields resulting from alternating currents. The design features of an operational amplifier are offered. In addition the nature of the phase shift contributed by mutual inductance elements in the feedback path is discussed. Magnetic fields with a flux density of one milligauss can be reduced by about two orders of magnitude with the system.
Design of a High-Speed Valve
Authors: Heitland Herbert H.
Published: February 2005

A high-speed valve has been designed for opening a deLaval nozzle in times less than 10−3 sec.
Short Dead-Time Corona-Streamer Counter for Neutrons
Authors: Tavendale A. J.
Published: February 2005

The long dead time and cathode erosion of the Rosenblum corona-spark counter for heavily ionizing radiations have been overcome by forming only the streamer stage of the spark by the addition of a few percent of some diatomic gas to nitrogen-contaminated argon in corona detectors of coaxial wire-cylinder geometry. The amplitude of the streamer pulse at the anode wire is large (>10 v) and distinctly greater than background, with a risetime of about 1 μsec. The recovery of the anode potential is made rapid (typically 5 μsec) by a simple RC anode circuit. Efficiencies for streamer formation of 7.5% for U234 α particles, 1.5% for (n, B10) α's and 5% for (n, U235) fission fragments have been obtained in coated counters.
High Precision, Semimicro, Hydrostatic Calorimeter for Heats of Mixing of Liquids
Authors: Anderson Ralph , Prausnitz J. M.
Published: February 2005

A calorimeter for measuring heats of mixing for binary liquid systems has been designed and constructed. The calorimeter utilizes an internal bellows assembly to eliminate completely the vapor space within the calorimeter and is equipped with an internal platinum resistance thermometer for temperature measurement, an external solenoid assembly to activate the stirring instrument and an internally mounted calibration heater and radiation shield to minimize radiative heat losses. An evacuated outer chamber minimizes heat losses by conduction. Measurements of the heats of mixing of cyclohexane-benzene, acetonitrile-benzene, and bromoethane-benzene yield a precision of 0.15%. The accuracy is estimated to be 0.25%.
Elastic Modulus Measurements at High Audio Frequencies Using a Vibrating Reed
Authors: Arends C. B.
Published: February 2005

High audio frequency elastic modulus measurements are possible using the vibrating reed if one can measure overtone frequencies. An electromagnetic detector is described which facilitates the measurement of these overtones, thereby extending the range of the vibrating reed to at least 10 kc.
Continuous Casting of Thermoelectric Materials
Authors: Hach Ralph J. , Brau Maurice J. , Burkhalter T. S.
Published: February 2005

A continuous casting apparatus has been developed that will produce thermoelectric material rapidly, reliably, and in large quantities with a minimum amount of labor. Bismuth telluride and alloys of Bi2Te3, Sb2Te3, and Bi2Se3 were cast in rods up to 70 in. in length. The deviation of the thermoelectric properties throughout the length of the rods was less than 5%.
Čerenkov Radiation Extensive Air Shower Telescope
Authors: Boley Forrest I. , Macoy Norman H.
Published: February 2005

A telescope is described which has been used to determine the directional characteristics of the Čerenkov radiation accompanying extensive cosmic ray air showers. The reflecting telescope has a 12.5-in. aperture, a 48-in. focal length and is of an off-axis design to permit the use of a 19 photomultiplier tube light detection array. Pulse-height information from each tube is fed to separate, spaced inputs on a delay line which supplies the resulting signal for oscilloscope presentation. The various pulse heights provide the Čerenkov radiation directional information. An average of 75% of the Čerenkov photons arrive at the telescope within a half-angle of 2.3°.
Accuracy of Bubble Location in a Bubble Chamber
Authors: Williams Robert W.
Published: February 2005

A measurement is reported of individual bubble locations along tracks of high-energy protons in a very small, short time scale pentane bubble chamber. Track distortions of the usual kind are greatly reduced in this system, so that one is measuring, to a precision of a few microns, the deviation of the true centers of the bubbles from the particle path. The average deviation in bubble position measurement is found from second differences to be 3.8 μ in space, most of which is shown to be accounted for by measurement errors. The average bubble is thus found to be centered on the track to better than 4 μ in hydrocarbons; however, an occasional bubble will be off by many times the average deviation. Arguments are advanced to show that a similar precision should obtain in hydrogen. This result is shown to be in general agreement with the bubble-chamber theory of Seitz.
Spectrometer for the Frequency Range 100 to 300 Mc
Authors: La Force Richard Conley
Published: February 2005

A spectrometer of the marginal oscillator type has been designed and constructed to operate over the range 100 to 300 Mc. The salient features of this spectrometer are that it may be frequency swept over a wide band, it is frequency modulated, and the extraneous amplitude modulation, often known as ``potato,'' is kept to a minimum and made largely independent of frequency. The spectrometer has been used with considerable success to study the nuclear resonance of Co59 in various ferromagnetic environments.
Simple Circuit for a Phoswich Scintillation Counter
Authors: Peterson L. E. , Nitardy J. H.
Published: February 2005

A simple, transistorized circuit is described which analyzes the frequency composition of the photomultiplier current pulse from a phoswich scintillation counter. The circuit generates a gate waveform from the fast current pulse of an organic scintillator, but not from the slower pulse from an inorganic crystal. Such a circuit finds application when the phoswich is used to provide an anticoincidence particle shield around a γ-ray spectrometer.
Gas Target for the Multiple-Gap, Broad-Range Spectrograph
Authors: Hoogenboom A. M.
Published: February 2005

A gas target with a very thin cylindrical window has been developed for use with the new M. I. T. multiple-gap, broad-range spectrograph. This gas target permits observation of reaction particles at all angles, except zero and 180°. It has been used with a window thickness of 0.5 μ and a gas pressure of 1 cm Hg for (d,p) angular-distribution experiments with a 7.5-Mev, 0.5-μa deuteron beam.
Effect of Ion Recombination Luminescence on the Linearity of Energy Response of Gas Scintillation Counters
Authors: Tavendale A. J.
Published: February 2005

The presence of columnar electron-ion recombination luminescence from α particles and fission fragments in an argon gas scintillation counter having a few percent N2 as waveshifter has been established. A decrease in luminescence yield with applied electric field indicates a loss of recombination luminescence by ion collection. For a U235 fission counter at two atmospheres pressure, a reduction in mean scintillation pulse height of 40% for fission fragments and 3% for background U234 alphas resulted at 1200 v/cm. It is concluded that columnar electron-ion recombination luminescence accounts for the considerable nonlinearity of energy response previously reported in gas scintillation counters for heavily ionizing particles.
Highly Stabilized and Sensitive Reactance Meter
Authors: Ichijo Bunjiro , Arai Tomokazu
Published: February 2005

This paper presents an explorative circuit system functioning as a highly stabilized and sensitive reactance meter with a wide range of application in various fields of scientific research and industrial operation. With a measuring range of 10−3 to 10+6 pf, it has a sensitivity of 5–10 μa/0.001 pf when measured through an ammeter with a full scale of 100 μa, and a stability of less than 1μa in terms of zero drift during several hours. Some experimental data are given for the appreciation of its characteristics.
The Solid Angle Subtended by a Cylinder
Authors: Guest P. G.
Published: February 2005

An approximation formula for the solid angle subtended at a point by a right circular cylinder is obtained and its error evaluated. The variation in the solid angle with displacement of the point from the symmetrical plane through the center of the cylinder at right angles to the axis is also discussed.
Pulsed Neutron System for Reactor Measurements
Authors: Kelly R. D. , Hamilton J. C. , Beavis L. C.
Published: February 2005

A complete pulsed neutron system has been developed for use in reactor reactivity measurements. The probe unit is small enough to fit into a reactor instrumentation pipe. The pulse-to-pulse variation in neutron output has been kept to a minimum by regulating the gas pressure in the neutron tube and by maintaining the same pulsing conditions regardless of pulsing rate. The total neutron output per pulse is in excess of 107 neutrons, and the maximum pulsing rate is 10 pulses/sec. The neutron tube has a useful life of 106 pulses. The system meets the design requirements; however, some additional work may be necessary if temperatures experienced during actual operation in the reactor affect the pressure regulating system of the tube.