摘要:

An inductively coupled ratio arm bridge for accurate measurement of the dielectric properties of materials at frequencies from 1 to 100 kc is described. Errors in the determination of very low loss tangents dependent on stray capacitance and nonideal ratio arm characteristics are discussed, and ways of decreasing them outlined. Design and performance data for the bridge are given.

ISSN:0034-6748    

DOI:10.1063/1.1718600

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Microwave absorption measurements have been made on the hydrogen sulfide molecule using a semiconfocal‐type Fabry‐Perot interferometer in the millimeter wave region. The 10, 1→ 11, 0and 21, 1→ 22, 0transitions of H2S33with S33in its natural concentration of 0.7% have been observed in this video spectrometer.Qvalues (Q=f/&Dgr;f) on the order of 56 000 were measured at 168 kMc in the semiconfocal resonator. A comparison is given between lines observed in the interferometer and those observed in standard waveguide absorption cells.

ISSN:0034-6748    

DOI:10.1063/1.1718601

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A comparison has been made of several ways of introducing different amounts of imperfection into neutron transmission monochromators of germanium in order to control their efficiency. The recommended technique is uniaxial plastic compression along the [110] direction at 650°C to a reduction in thickness equal to or slightly under 2.5%. Tests indicate an improvement in efficiency in both single‐crystal and power diffractometry of a factor of 25 to 40 over that of an undeformed slab.

ISSN:0034-6748    

DOI:10.1063/1.1718602

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A description is given of an apparatus capable of measuring instantaneous voltages in the presence of heavy current discharges. The basic advantages of the system are (1) a single ground connection which is independent of the two points of the desired voltage, (2) cancellation of induced voltages in measuring circuit by electronic means with bandpass depending only upon amplifiers used, (3) the cancellation of the measuring circuit pickup is insensitive to large changes in the geometry of the measuring circuit.

ISSN:0034-6748    

DOI:10.1063/1.1718603

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A new energy‐accumulation method has been found for accelerating very small but usable beams of artificial fission fragments such as bromine and iodine ions to energies three times higher than those previously available from tandem Van de Graaff accelerators. Energies up to 120 MeV now available cover completely the energy range found for the fission particles from uranium. The ions have been used to study the behavior of silicon solid‐state fission‐particle detectors of many types. For the first time direct calibration methods are available to aid in experimental studies of the fission process. Further work will be directed toward an experimental study of the stopping power of various elements for heavy ions.

ISSN:0034-6748    

DOI:10.1063/1.1718604

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Application of a unique calorimetry technique to the measurement of extremely high gas enthalpies and temperatures was described previously. The technique is based on measurement of the change in coolant fluid energy which is observed when a continuously flowing sample of the ``unknown'' gas through the probe is shut off. Effects of external cooling requirements and radiation are thereby canceled, permitting direct measurement of local gas enthalpy (from which, under certain conditions, gas temperature may be deduced). One of the principal problems encountered in the application of this device is its sensitivity under different conditions. The present paper describes an approximate method for estimating this sensitivity. Comparison of the results with measured sensitivities indicated appreciable scatter, but was adequate to confirm the general approach.

ISSN:0034-6748    

DOI:10.1063/1.1718605

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Explosions (lead azide) at the two ends of a crystal rod are made simultaneously (to <1/50 &mgr;sec) using exploding wires as detonators. The resulting elastic pulses meet and reinforce at the center of the bar to produce transient plastic flow, and the pulse length is short enough to allow dislocation velocities to be measured up to the transonic range.

ISSN:0034-6748    

DOI:10.1063/1.1718606

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

It is shown that multiple readings of thermoluminescent dosimeters can be made by using the ``steady‐state'' phosphorescence brightness at a temperature well below the glow peak temperature. Following such readings the devices can be read in the normal way, with appropriate calibration factors to correct for the partial exhaustion of the phosphor by the phosphorescence readings. The behavior of dosimeters in the phosphorescence method of reading appears to be more dependent on constructional details than in the normal thermoluminescent method.

ISSN:0034-6748    

DOI:10.1063/1.1718607

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

An electronic ratiometer with synchronous switching has been built, permitting the measurement of mass abundance ratios with a single‐beam mass spectrometer. The ratiometer eliminates some of the drawbacks in the measurement of isotope abundance ratios with a double‐beam mass spectrometer and allows mass abundance ratios differing by many mass units to be measured, giving the possibility of following the ratios of reactants and products in fast gas kinetic studies.

ISSN:0034-6748    

DOI:10.1063/1.1718608

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

An isochronal differential‐type microcalorimeter has been designed and constructed. As a result of its simple design it is very easy to handle the samples and assemble the calorimeter. Important to the operation of the calorimeter is a program, also working on the differential principle, that provides linear temperature rise of the samples. This calorimeter is used to measure very small energy releases such as those found in precipitation, stored energy, etc. It is demonstrated that the calorimeter is easily capable of measuring 0.005 cal with a probable error of the order of 1 to 2%.

ISSN:0034-6748    

DOI:10.1063/1.1718609

出版商:AIP    

年代:1963

数据来源: AIP