摘要:

Three items of equipment are described in detail; (1) A simple‐piston and cylinder device capable of generating pressures to 50 000 atmospheres simultaneously with temperatures of 5000°C, (2) a tetrahedral‐anvil device that has been successfully tested at 100 000 atmospheres and 3000°C, and (3) a stepped‐piston device capable of developing pressures to 200 000 atmospheres at room temperature.In addition consideration is given to such problems as (a) geometrical elements of design, (b) higher strength materials, (c) use of mechanical anisotropy in design, (d) electrical leads, (e) thermal and electrical insulation, (f) solid pressure transmitting media, (g) binding rings, (h) internal generation of pressure, (i) multistaging, and (j) calibration.

ISSN:0034-6748    

DOI:10.1063/1.1716172

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A system is described for measuring and recording rapid (3 cps) fluctuations of refractive index, humidity (vapor pressure), and temperature using fast response thermistor beads. The system utilizes wet and dry thermistors whose changes are fed into a simple analog computer. The accuracy of the system is 1 part in 107for refractive index, about 0.1 mbar for humidity and 0.1°C for temperature.Measurements can be obtained to an altitude of 5000 ft above the measuring site, with an altitude accuracy of ±50 ft under optimum weather conditions.

ISSN:0034-6748    

DOI:10.1063/1.1716173

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

Photomultiplier evaluation of scintillation performance is considered in the light of its marked dependence on spectral shape effects in the emission spectrum of the scintillator, in photon absorption of cell, reflector and photomultiplier window, and in the photoelectric conversion process. Relative pulse height data indicating gross differences in spectral sensitivity are presented for a group of 132 photomultipliers (types 6292 and 6342). A fluorescent converter for measuring the quantum output of liquid scintillators is described.Six scintillator solutions with fairly evenly spaced mean emission wavelengths from 3360 to 4660 A are evaluated for relative pulse height and relative photon output.Suggestions are presented for desirable methods for measuring the performance of scintillators.

ISSN:0034-6748    

DOI:10.1063/1.1716174

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

The decay statistics of a radioactive parent‐short‐lived daughter mixture is simulated by means of a circuit which superposes two random series. Daughter half‐life and pulse composition can be varied between wide limits. The output distribution of a differential delay analyzer for high input rates, containing disintegrations of short‐lived isomeric states in the millisecond range is tested by using the simulator. A formula for such output distributions is given.

ISSN:0034-6748    

DOI:10.1063/1.1716175

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A simple scintillation counter system is described which monitors the average energy of particles in the external beam of a cyclotron and simultaneously serves as a current integrator. Energy changes are continuously presented on a chart recorder, thus allowing the machine energy to be held constant to a high degree of accuracy over extended runs. In typical operation using 14‐Mev deuterons, the average energy may be held constant to within 0.07%.

ISSN:0034-6748    

DOI:10.1063/1.1716176

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A transistorized refraction seismograph has been developed based on pulse systems techniques. This results in direct visual time indications, major reductions in operating complexity, size, and weight, and the elimination of the necessity for photographic processing and the use of explosives. A 4‐kc crystal oscillator serves as the time base. The signal passes through a gate circuit to an electronic counter; the gate is opened at the time a sound wave enters the earth and is closed at the time the sound reaches a detector on the surface. The time‐distance data can be interpreted in terms of depths to subsurface layers and the nature of subsurface materials.

ISSN:0034-6748    

DOI:10.1063/1.1716177

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

An air‐gap capacitor has been designed to measure the dissipation factor and dielectric constant of sheet insulating materials without making contact with the dielectric. Tests indicate that the loss tangent and dielectric constant values obtained are comparable to those obtained with intimate‐contact electrodes. This method provides a means of measuring, over a wide range of thickness, sheet materials which cannot have electrodes intimately fastened to their surfaces.

ISSN:0034-6748    

DOI:10.1063/1.1716178

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A liquid hydrogen bubble chamber with useful volume 6¼×2¾×3 inches has been built which is expanded by a piston operating in the liquid hydrogen. Temperature control is provided by regulating the pressure in the hydrogen reservoir. Satisfactory tracks have been obtained with maximum expansion ratio of 3%, expansion time of about 5 msec, and chamber temperatures from 25.3 to above 27°K. Photographs have been taken with time delay between particles passing through chamber and light flash of 0.05 to 2.0 msec.

ISSN:0034-6748    

DOI:10.1063/1.1716179

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

An improved Pound‐Knight‐Watkins nuclear magnetic resonance spectrometer is described. The improved spectrometer has an arrangement which reduces frequency fluctuations by a factor of 5–10 at 30 Mc. The spectrometer is capable of stable operation, with sensitive metering, down to an rf level of 0.01 v across the sample coil, an improvement of almost an order of magnitude. The instrument also allows direct measurement of the derivative of &khgr;′, the real part of the susceptibility of the sample.

ISSN:0034-6748    

DOI:10.1063/1.1716180

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A cryoscope is described which was designed for the accurate measurement of freezing points of molten salts under controlled atmospheres. It possesses several advantages over apparatus in the published literature, especially when used with solutions which attack or embrittle the glass container.The ancillary apparatus used with the cryoscope is also described, and the features of the apparatus are discussed. Examples are given to show how several problems of molten salt cryoscopy under controlled atmosphere have been satisfactorily overcome.

ISSN:0034-6748    

DOI:10.1063/1.1716181

出版商:AIP    

年代:1958

数据来源: AIP