摘要:

This paper describes a simple and accurate method for the measurement of the phase difference between two sinusoidal voltages and an instrument for making the measurement. It is shown that measurement accuracy sufficient for most ordinary purposes can be obtained through the use of very simple circuitry, and that measurement errors can be made arbitrarily small by resorting to more complex circuitry. The instrument is compact and convenient in use.

ISSN:0034-6748    

DOI:10.1063/1.1745562

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

The construction and use of an electron tube potentiometer designed for circuits involving high resistances to the order of 100 megohms are described.

ISSN:0034-6748    

DOI:10.1063/1.1745563

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

A method for cooling x‐ray tubes was devised, based on the principle of relative motion between the target and focal spot. The electron beam is deflected by a rotating magnetic field so that the focal spot moves in a circle upon the target face. Simultaneously, the tube itself is gyrated (without rotation about its axis) so that any point on the target describes an equal circle. The two rotations are equal in frequency but phased 180 degrees from each other. Thus the focal spot remains stationary in laboratory space. The advantages are (1) it is adaptable to most x‐ray tubes with target face perpendicular to the tube axis, and target diameter twice that of the longest focal spot dimension, without any modification of tube design; (2) it combines the benefits of a rotating target, water‐cooled target, and line focus without the need for rotating joints or vacuum connections. Tubes, operating continuously for hours at a time at a gyrating frequency of 6 r.p.s. have been cooled successfully by this method without observable shifting of the focal spot in laboratory space.

ISSN:0034-6748    

DOI:10.1063/1.1745564

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

The preparation and use of calibrated RaDEF equilibrium sources for absolute beta‐counting is described. The sources are essentially weightless and are mounted on a thin backing to reduce self‐absorption and back‐scattering correction problems. Calibration was done by determination of the alpha‐disintegration rate of RaF in a parallel plate alpha‐ionization chamber. No secondary standards are required and the sources can be recalibrated at any time.As an example of the application of such standards, details of the calibration of a P32solution distributed by the Bureau of Standards for intercalibration in February 1949 are given. The final result is 88.8 mrd/ml at 8 A.M. C.D.T. March 1, 1949. The precision of the measurement is 0.3 percent. The accuracy is estimated to be 1–2 percent.

ISSN:0034-6748    

DOI:10.1063/1.1745565

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

A multiple gamma‐ray counter is described, composed of 24 counter tubes connected in parallel. The tubes have Bi‐plated brass screen cathodes and are placed inside the same envelope. Relative and absolute values for the efficiency of the counter were determined experimentally in the range 0.28 to 2.62 Mev. Compared to a single brass counter of similar dimensions, the multiple counter shows for gamma‐rays of, say, 0.7 Mev energy a tenfold increase in efficiency. Its starting voltage is 5–600 volts lower.The ``effective resolving time'' of the multiple counter appears to be 3 to 4 &mgr;seconds.The counting rate curve seems to follow the inverse‐square law down to the shortest counter‐source distances. The solid angle subtended by the multiple counter for sources, placed in its middle, is nearly 4&pgr;.

ISSN:0034-6748    

DOI:10.1063/1.1745566

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

The high density, transparency, and chemical inertness of calcium and cadmium tungstates, together with their reasonable luminescent efficiencies when stimulated with high energy radiation, strongly suggest their use as phosphors in scintillation counters for gamma‐ray detection. Some of the properties of these crystals are reported and compared with anthracene. It is shown that with proper design, the total anode current produced by a given source is several times greater with the tungstates than with anthracene, although the latter has a more favorable pulse size distribution. Cadmium tungstate has a zero temperature coefficient of luminescence up to 40°C and shows no afterglow after exposure to intense radiation.

ISSN:0034-6748    

DOI:10.1063/1.1745567

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

The low frequency range of an audio oscillator can be extended to d.c. by means of a heterodyning circuit using power line frequencies as a reference. The voltage wave forms are essentially sinusoidal and can be used for certain novel tests. A theoretical discussion of the beating phenomenon is included with particular applications and observed results.

ISSN:0034-6748    

DOI:10.1063/1.1745568

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

The sensitivity of the RCA 1P21 photo‐multiplier to gamma‐radiation has led to the investigation of the characteristics of this tube as a gamma‐ray detector. The range, linearity, directional dependence, temperature dependence, applied voltage regulation requirements, and radiation energy dependence were determined for several tubes. Preliminary results concerning the ability of the tube to maintain a calibration are given. A basic circuit for such a detector is given.

ISSN:0034-6748    

DOI:10.1063/1.1745569

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

An apparatus is described by means of which the size and the charge of large numbers of microscopic particles can be simultaneously determined. The method is based on Hopper and Laby's work on the determination of the electronic charge, i.e., horizontal deflection of particles settling under gravity recorded photographically. The procedures involved are given in some detail, and the nature and limitations of the general results are discussed. Simplicity of operation and design are emphasized to render the instrument a workable tool in industrial research.

ISSN:0034-6748    

DOI:10.1063/1.1745570

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

The spectral sensitivities of Kodak No‐Screen and Kodak Industrial Type K X‐Ray Films were determined in the region between 0.2 and 2.5A using the filteredKfluorescence of several irradiated elements as approximately homogeneous radiation. Exposures in roentgens were obtained with an air ionization chamber designed especially for the purpose. Curves are given showing the number of roentgens incident on the film which will give a developed photographic density of 1.0 above fog for the various wave‐lengths. TheKlimits of silver and bromine are prominent. The maximum sensitivity in terms of roentgens occurs at about 0.4A, but the marked decrease found by other observers at shorter wave‐lengths is probably obscured by inaccuracies. From the energy value of the roentgen, the sensitivity of the films is expressed as the incident ergs per square centimeter required to produce a density of 1.0 above fog. Computations from these results show that as the wave‐length increases the films utilize theabsorbed energymore efficiently. On the other hand, high energyquantaare more efficient than low energy quanta but not in proportion to their energy. In addition to the more or less gradual change with wave‐length of efficiency of utilization of absorbed energy, there is evidence for sudden jumps at theKlimits of Ag and Br. Qualitative explanations are given for the observed changes in efficiency.

ISSN:0034-6748    

DOI:10.1063/1.1745571

出版商:AIP    

年代:1950

数据来源: AIP