摘要:

A magnetron cold cathode ion source (CCIS) has been developed for ultrahigh vacuum residual gas analysis. The purpose is to eliminate the spurious spectra produced by the conventional hot filament source and to obtain greater sensitivity. A commercial quadrupole mass analyzer was used to evaluate source performance and potential. Resolution equaled that obtained with a hot filament source, giving mass invariant peak separations, with 10% valleys, of 1.0 amu below 150 amu and 0.7 amu below 50 amu. Sensitivities exceeded those obtained with a hot filament source, operated at a 3 mA emission current, by factors of 1.5 to 4.6, depending on pressure and mass. The corresponding CCIS sensitivities, at 1‐amu peak separation, were 0.4 mA/Torr for mass 28 at 3×10−9Torr and 1.2mA/Torr for mass 40 at 1×10−7Torr. Experiments indicated a potential tenfold further sensitivity improvement if a quadrupole with a higher rf potential were used; by increasing quadrupole dimensions a still greater fraction of the source internal sensitivity, which is in the vicinity of 1 A/Torr, may be realized.

ISSN:0034-6748    

DOI:10.1063/1.1720549

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The design, construction, and performance of a 320‐liter cylindrical stopping K+detector is described. The efficiency of the detector is measured to be about 70%.

ISSN:0034-6748    

DOI:10.1063/1.1720550

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A modified mutual inductance bridge incorporating a commercial phase‐lock amplifier has been used to measure low temperature bulk resistivities in the range from 1 to 10 000 n&OHgr; cm. No electrical contact is required with the spherical metal samples, so that possible heat leakage along electrical leads is eliminated, and measurements can be made below 40 mdeg Kelvin using a dilution refrigerator. The bridge circuit, capable of determining resistivity changes with a precision of better than 0.3%, is described.

ISSN:0034-6748    

DOI:10.1063/1.1720551

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

This paper describes a new tunnel diode‐transistor ring counter employing current mode operation. With suitably shaped input pulses it is capable of operating reliably at input repetition rates in excess of 500 MHz.

ISSN:0034-6748    

DOI:10.1063/1.1720552

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

An instrument is described which is a simple, accurate, reliable, and inexpensive device for continuously measuring and recording angular position or deflection. Incorporated in a torsion‐effusion apparatus it permits the visual observation of phase changes, deviations from molecular flow, and approach to equilibrium. The usual alignment problems associated with a lamp and scale are eliminated.

ISSN:0034-6748    

DOI:10.1063/1.1720553

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A new technique is described which provides for the study of x‐ray diffraction from a small selected region in the interior of a body. The method is of particular value for the measurement of interior elastic strain and will permit the complete evaluation of a triaxial state of stress. The collimation is appropriate for studies of either single crystals or polycrystalline material. Evaluations on single crystals of LiF with Mo K&agr;1demonstrate that a conventional line x‐ray source provides useful diffracted power from a crystal volume of less than 10−4cm3located at a depth below the surface exceeding 0.3 cm. A strain reproducibility of better than 2×10−5was attained in measurements at several depths in an unstrained crystal, and elastic strain evaluations were made through the thickness of a single crystal beam loaded in four‐point bending.

ISSN:0034-6748    

DOI:10.1063/1.1720554

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A spark chamber film reader has been developed which uses a computer directed cathode ray spot as the scanning light source. The equipment features data processing speed of 20 000 points per second while achieving position resolution of 4 &mgr;. Search modes and film areas covered are controlled by the computer software giving wide flexibility.

ISSN:0034-6748    

DOI:10.1063/1.1720555

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The surface of a single crystal having etch steps of known heights can be used for magnification calibration. The etched basal surface of a hexagonal ferrite single crystal has etch steps whose heights are a precisely known function of its unit cell height. Depending upon the mixed‐layer stacking arrangement of the hexagonal ferrite phase such etch steps can have heights ranging in increments from 11.6 to 300 Å. After careful selection of a characterized hexagonal ferrite single crystal, it is etched in 1:1 HCl at 90°C until etch features are visible on the basal surface. The crystal is replicated by the one step method. The angle used for shadowing (from 1:1 to 3:1) must be accurately set since any error in the shadow angle will produce a corresponding error in the magnification. The shadow cast by the etch steps on the replica as viewed in the electron microscope is then used as the standard for calibration of magnifications in excess of 10 000 times.

ISSN:0034-6748    

DOI:10.1063/1.1720556

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Considerations for gravity gradiometer application have established the need for predicting gradiometer response to mass distributions of particular interest. A digital computer program has been developed to simulate the rotating gravitational mass sensor, and to map the gradient contours of the gravitational field created by an arbitrary mass distribution. This analysis demonstrates the interaction of the gradiometer with seond and higher order gravitational gradients. The information about the mass distribution of an object was found to increase with the gradient order. Considered in this study is the ``cruciform'' mass sensor, now being developed by Hughes Research Laboratories. This rotating gradiometer is theoretically capable of measuring the second, sixth, tenth, etc., order gradient. We are presently engaged in laboratory experiments which combine with these computer results in the understanding of gradient‐sensor interaction. This paper gives a basic introduction to gravitational tensors, followed by a mathematical formulation of the gradiometer model. Computer results are included which demonstrate the gravitational gradient contours associated with some selected mass distributions.

ISSN:0034-6748    

DOI:10.1063/1.1720557

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A simple, versatile, magnetic float densimeter that can be used to measure the density of liquids as a function of temperature is described. The system has been calibrated with water from 20 to 50°C demonstrating a sensitivity of 0.3 ppm and a precision of 2 ppm. The accuracy of the densimeter has been verified by measuring the densities of NaCl solutions at 25°C. Excellent agreement with previously published data was achieved.

ISSN:0034-6748    

DOI:10.1063/1.1720558

出版商:AIP    

年代:1967

数据来源: AIP