摘要:

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 2×105r. 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.

ISSN:0034-6748    

DOI:10.1063/1.1716870

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

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.

ISSN:0034-6748    

DOI:10.1063/1.1716871

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

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 (1.8×10−9sec). The data are presented in the form of a chart record.

ISSN:0034-6748    

DOI:10.1063/1.1716872

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

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.

ISSN:0034-6748    

DOI:10.1063/1.1716873

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

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 CFCl3line having a calculated absorption coefficient of 3.9×10−11cm−1. The relationship between recorder deflection and absorption coefficient is discussed.

ISSN:0034-6748    

DOI:10.1063/1.1716874

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

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.

ISSN:0034-6748    

DOI:10.1063/1.1716875

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

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.

ISSN:0034-6748    

DOI:10.1063/1.1716876

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

A solid‐state constant current supply which operates in the current range of 1 to 100 &mgr;a 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 8×108ohms.

ISSN:0034-6748    

DOI:10.1063/1.1716877

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

A method for measuring the diamagnetic or paramagnetic susceptibilities of small particles of diameters of 1 to 100 &mgr; 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.

ISSN:0034-6748    

DOI:10.1063/1.1716878

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

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.

ISSN:0034-6748    

DOI:10.1063/1.1716879

出版商:AIP    

年代:1960

数据来源: AIP