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Dec 1960

Volume 31, Issue 12, pp. 1263-1360

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New Thermoluminescent Dosimeter

James H. Schulman, Frank H. Attix, Edward J. West, and Robert J. Ginther

Rev. Sci. Instrum. 31, 1263 (1960); http://dx.doi.org/10.1063/1.1716870 (7 pages) | Cited 23 times

Online Publication Date: 29 December 2004

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A simple dosimeter design is described in which a thermoluminescent phosphor is mounted on an electrically heatable support in an evacuated or gas‐filled envelope. With CaF2:Mn as the phosphor, the device detects gamma‐ray doses in the milliroentgen range and is linear in response up to at least 2×105 r. Dose readings can be made in less than a minute with simple instrumentation requiring no darkroom facilities. The dosimeter may be reused many times. The response is independent of dose rate at least over the range 10 mr∕min to 7000 r∕min. With suitable tin shields the response is independent of energy over the range 40 kev to 1.25 Mev. The advantages of this device for monitoring of personnel in health physics operations are pointed out.

Design of Mutual Inductance Bridge for Cryogenic Measurements

L. D. Jennings

Rev. Sci. Instrum. 31, 1269 (1960); http://dx.doi.org/10.1063/1.1716871 (6 pages) | Cited 2 times

Online Publication Date: 29 December 2004

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It is shown that a mutual inductance bridge may be designed whose components are small and which allows a magnet to be placed around the unknown with no loss in sensitivity and accuracy. An instrument which embodies these principles is described, and techniques are given for obtaining accurate and rapid measurements of the real and imaginary components of the unknown.

Instrument to Measure Fluorescence Lifetimes in the Millimicrosecond Region

R. G. Bennett

Rev. Sci. Instrum. 31, 1275 (1960); http://dx.doi.org/10.1063/1.1716872 (5 pages) | Cited 51 times

Online Publication Date: 29 December 2004

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An instrument to measure fluorescence lifetimes of the order of millimicroseconds is described. Following excitation by a hydrogen flash lamp, the fluorescence is observed stroboscopically with a gated photomultiplier. The method of gating is novel and achieves a time resolution comparable with fast oscilloscopes (1.8×10−9 sec). The data are presented in the form of a chart record.

NaI(Tl) Summing Compton Spectrometer

H. Takekoshi

Rev. Sci. Instrum. 31, 1280 (1960); http://dx.doi.org/10.1063/1.1716873 (6 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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The paper describes a new method of measuring gamma‐ray energy by using two sodium iodide crystals. The sum of two pulses is to be taken: one from a crystal which scatters gamma rays by the Compton effect, and the other from a second crystal which receives the scattered photon. In comparison with the scintillation Compton spectrometer hitherto developed, this method is good both in efficiency and in resolution.

Detectors for Microwave Spectrometers

Maurice W. Long

Rev. Sci. Instrum. 31, 1286 (1960); http://dx.doi.org/10.1063/1.1716874 (4 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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The sensitivity of detectors used in sample modulated microwave spectrometers is investigated. Characteristics of crystal diodes and barretters as functions of microwave power are compared with an ideal detector operating at room temperature. A spectrograph is described which was used to measure a CFCl3 line having a calculated absorption coefficient of 3.9×10−11 cm−1. The relationship between recorder deflection and absorption coefficient is discussed.

Measurement of Betatron Oscillation Frequencies in the Cosmotron

M. Q. Barton

Rev. Sci. Instrum. 31, 1290 (1960); http://dx.doi.org/10.1063/1.1716875 (2 pages) | Cited 2 times

Online Publication Date: 29 December 2004

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Coherent betatron oscillations are excited by an impulse magnetic field in one straight section of the cosmotron. The resulting oscillations can be observed using a communications receiver connected to the radial position induction electrodes.

Modified Double Slit Interferometer for Shock Wave Investigations

George H. Markstein

Rev. Sci. Instrum. 31, 1291 (1960); http://dx.doi.org/10.1063/1.1716876 (6 pages)

Online Publication Date: 29 December 2004

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The possibility of applying the Rayleigh double slit interferometer for shock wave investigations has been explored. In common with Rayleigh interferometers currently used for diffusion, electrophoresis, and ultracentrifuge studies, the instrument adapted for the present application contained a cylinder lens for bringing the interference fringes and the test section into simultaneous focus at the camera image plane. However, in contrast to previous applications, it was found desirable in the present work to let the light paths through both slits traverse the test section. This arrangement required a modification which consisted of tilting the axis of the cylinder lens, and the light source slit, with respect to the conventional orientation parallel to the refractive index gradient. Conditions under which a useful interferogram is obtained with this instrument are derived, and results of preliminary experiments are presented. Compared with the Mach‐Zehnder interferometer, the double slit instrument has the advantages of greater simplicity and ease of adjustment, lower cost, and offers the possibility of combining the interferometer with an inclined slit schlieren system.

Constant Current Supply for Very High Resistance Loads

Robert W. Haisty

Rev. Sci. Instrum. 31, 1297 (1960); http://dx.doi.org/10.1063/1.1716877 (2 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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A solid‐state constant current supply which operates in the current range of 1 to 100 μa with load resistances up to several hundred megohms is described. The system is battery operated, and allows one side of the load resistance to be grounded. The current is controlled by a gallium arsenide photoresistor in series with the load. The load current is balanced against a standard current and the difference is fed to a chopper‐amplifier which drives a small lamp focused on the photoresistor. The gain of the amplifier is sufficiently high that a very small unbalance in current will drive the lamp to full output; thus, the photoresistor keeps the load current very near the standard current for any value of load resistance from zero up to the dark resistance of the photoresistor, typically about 8×108 ohms.

Magnetic Susceptibility Measurements of Single Small Particles

S. J. Gill, C. P. Malone, and M. Downing

Rev. Sci. Instrum. 31, 1299 (1960); http://dx.doi.org/10.1063/1.1716878 (5 pages) | Cited 11 times

Online Publication Date: 29 December 2004

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A method for measuring the diamagnetic or paramagnetic susceptibilities of small particles of diameters of 1 to 100 μ is described. Theoretical considerations are given for the design of the apparatus and for the interpretation of measurements. Susceptibility determinations of polystyrene latexes and red blood cells show the use of the method.

Floating Zone Crystals Using an Arc Image Furnace

R. P. Poplawsky and J. E. Thomas

Rev. Sci. Instrum. 31, 1303 (1960); http://dx.doi.org/10.1063/1.1716879 (6 pages) | Cited 5 times

Online Publication Date: 29 December 2004

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A floating zone technique for growing crystals of medium high melting point materials with an arc image furnace is presented. This technique has been successfully applied to silicon. The oxygen concentration, resistivities, and dislocation densities of resulting crystals were determined to make possible a comparison with crystals obtained by standard methods. In general this comparison is favorable. Considerations of floating zones, maximum power, and flux distribution indicate that floating zone techniques combined with an arc image furnace are promising in connection with the growth of good quality crystals of a variety of high melting point materials.

Method of Studying Travel Time Anomalies of High Frequency Radio Waves

Gordon Lerfald and Paul Scheibe

Rev. Sci. Instrum. 31, 1309 (1960); http://dx.doi.org/10.1063/1.1716880 (3 pages)

Online Publication Date: 29 December 2004

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A device utilizing pulse techniques has been built for automatic measurement of changes in radio wave travel times. The equipment uses a combination of amplitude, time, and frequency selection for discrimination against unwanted signals. The received signals from U. S. time standard station WWV are sampled at 1‐sec intervals to measure changes in the time of reception of the 1‐sec timing pulses transmitted by WWV. The changes in travel time can give information on the vertical velocity of a virtual reflection point in the ionosphere and other factors of interest in the study of the ionosphere.

Accumulating Digitizer System

Thomas H. Fields and Robert W. Findley

Rev. Sci. Instrum. 31, 1312 (1960); http://dx.doi.org/10.1063/1.1716881 (6 pages) | Cited 3 times

Online Publication Date: 29 December 2004

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A system is described for digital measurement and automatic recording of linear or angular position. An adding‐subtracting scaler is used to accumulate pulses generated by the digitizing element. Several of the major components are commercially available. The performance of the system as used for coordinate measurements on bubble chamber photographs is discussed.

Low Frequency Underwater Sound Velocity Meter

John D. Shaffer

Rev. Sci. Instrum. 31, 1318 (1960); http://dx.doi.org/10.1063/1.1716882 (3 pages)

Online Publication Date: 29 December 2004

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An underwater sound velocity meter is described which employs an open‐end heavy‐walled tube for a resonant cavity. The water column is excited into vibration by a sound source near one end, while a hydrophone probe at the tube center registers the pressure amplitude. A sharp resonance (Q=450) permits making relative measurements with an uncertainty of less than 0.2 m∕sec when the fundamental mode (f≈570 cps) is used.

Velocity Modulation and Related High Frequency Deflection Errors of the Traveling Wave Deflection System

Jacob Goldberg

Rev. Sci. Instrum. 31, 1320 (1960); http://dx.doi.org/10.1063/1.1716883 (6 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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The potential and electric field distributions in a traveling wave deflection system are derived for a sinusoidal deflecting signal. They are then generalized for application to arbitrary deflecting signals. It is shown that a longitudinal field exists and depends on the odd derivatives of the signal. This component of the field modulates the velocity of the beam and gives rise to errors in focusing and time axis position. The velocity modulated beam is then dispersed by the time axis deflection system. The nonuniformity which must exist in the deflecting component of the field is shown to depend on the even derivatives of the deflecting signal. The nonuniformity gives rise to dispersion and errors in deflection of the beam by the traveling wave deflection system. Generalized expressions for these errors are derived, and the errors are evaluated for a representative set of conditions.

Device for Generating a Low Temperature, Highly Ionized Cesium Plasma

Nathan Rynn and Nicola D'Angelo

Rev. Sci. Instrum. 31, 1326 (1960); http://dx.doi.org/10.1063/1.1716884 (8 pages) | Cited 151 times

Online Publication Date: 29 December 2004

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A device for generating a linear, highly ionized, low temperature cesium plasma is described. The plasma is generated by having the output of cesium atomic beam ovens impinge on hot tungsten plates placed at both ends of a cylindrical vacuum chamber. The walls of the chamber are cooled so that neutral cesium condenses on them. The theory of the device, designated as the Q machine, is presented and some experimental results given. The maximum density achieved was 2×1012∕cm3, with an estimated fractional ionization of 99%, and a confining field of 5900 gauss.

Simple Apparatus for the Growth of Germanium Dendrites

Reginald F. Lever, John K. Powers, John L. Richards, and Harry V. Sirgo

Rev. Sci. Instrum. 31, 1334 (1960); http://dx.doi.org/10.1063/1.1716885 (2 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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A description is given of a simple resistance‐heated apparatus for pulling germanium dendrites. Two distinct types of growth are obtainable. When the correct conditions are achieved, growth may continue indefinitely. A typical product is a 2 m length of essentially uniform ribbon 1.5 to 3 mm in width, and 0.1 mm thick.

A Deformation Calorimeter

Robin O. Williams

Rev. Sci. Instrum. 31, 1336 (1960); http://dx.doi.org/10.1063/1.1716886 (6 pages) | Cited 5 times

Online Publication Date: 29 December 2004

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A calorimeter has been constructed which adiabatically deforms metals with a known mechanical energy. The energy which is stored in the sample as a result of the deformation is the difference between the supplied energy and the heat which is found by the increase in sample temperature. It is also possible to follow subsequent energy releases which take place immediately following the deformation; for some materials this release can be an appreciable fraction of the stored energy. The results for the stored energy are considered to be accurate to approximately 10%.

Modified Coaxial Powder X‐Ray Camera

D. Jerome Fisher

Rev. Sci. Instrum. 31, 1341 (1960); http://dx.doi.org/10.1063/1.1716887 (3 pages)

Online Publication Date: 29 December 2004

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Herewith is described a modified form of the x‐ray powder camera that employs a flat specimen mounted normal to the direct beam which proceeds along the axis of the cylindrical film, as first constructed by L. L. Hawes [Acta. Cryst. 12, 443 (1959)]. Also presented are details of the techniques for mounting specimens, measuring films, and correcting these for errors. Theoretical discussion of the advantages and disadvantages of this type of camera, together with a simplified least‐squares technique for interpreting the data, are given in two papers by Hawes now in press. An example of the high accuracy obtained with this camera is described in Hawes.

Total Absorption Gamma‐Ray Spectrometers Utilizing Anticoincidence Shielding

R. W. Perkins, J. M. Nielsen, and R. N. Diebel

Rev. Sci. Instrum. 31, 1344 (1960); http://dx.doi.org/10.1063/1.1716888 (6 pages) | Cited 9 times

Online Publication Date: 29 December 2004

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Two total absorption gamma‐ray spectrometers utilizing anticoincidence shielding are described. One of these consists of a 5‐in. diam by 5‐in. thick NaI(Tl) well crystal enclosed in a 26‐in. diam by 30‐in. high plastic phosphor. The plastic phosphor serves as the anticoincidence guard. The second spectrometer consists of a 3‐in. diam by 3‐in. thick NaI(Tl) crystal with a 9⅜‐in. diam by 8☒‐in. thick NaI(Tl) well crystal as its anticoincidence guard. With the anticoincidence shielding, and a point source in the well of the 5×5‐in. crystal, the Compton portion of the Zn65 spectrum is reduced by a factor of about 5, while the Compton portion of the Co60 spectrum (below 1 Mev) is reduced by factors of 20 to 25. With these point sources on top of the 3×3‐in. solid crystal, these Compton regions are reduced by factors of about 4 and 14, respectively. These anticoincidence shielding arrangements also provide background reductions of a factor of 2 to 5 in the energy region below 3 Mev. The response of these spectrometers to other gamma‐ray energies is included. The photomultiplier mounting arrangements for the large NaI(Tl) and plastic phosphors, and the resolutions of the plastic and NaI(Tl) crystal are discussed.
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Integration of Current through Getter‐Ion Pumps

J. R. Fendley

Rev. Sci. Instrum. 31, 1350 (1960); http://dx.doi.org/10.1063/1.1716889 (1 page) | Cited 2 times

Online Publication Date: 29 December 2004

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Abstract Unavailable

Low Temperature Static Seals Using Elastomers and Plastics

D. H. Weitzel, R. F. Robbins, G. R. Bopp, and W. R. Bjorklund

Rev. Sci. Instrum. 31, 1350 (1960); http://dx.doi.org/10.1063/1.1716890 (2 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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Abstract Unavailable

Achievement of Extremely Homogeneous Magnetic Fields

L. S. Goodman

Rev. Sci. Instrum. 31, 1351 (1960); http://dx.doi.org/10.1063/1.1716891 (2 pages) | Cited 3 times

Online Publication Date: 29 December 2004

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Abstract Unavailable

Inexpensive Safety Switch for Water‐Cooled Equipment

R. Hawley

Rev. Sci. Instrum. 31, 1352 (1960); http://dx.doi.org/10.1063/1.1716892 (2 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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Abstract Unavailable

Leveling System for Liquid Nitrogen

Stanley Leefe and Morris Liebson

Rev. Sci. Instrum. 31, 1353 (1960); http://dx.doi.org/10.1063/1.1716893 (2 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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Abstract Unavailable

Viewing Probe for High Voltage Pulses

Walter LeCroy and Jerome Rosen

Rev. Sci. Instrum. 31, 1354 (1960); http://dx.doi.org/10.1063/1.1716894 (1 page)

Online Publication Date: 29 December 2004

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Abstract Unavailable
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