摘要:

The well developed techniques of coherent detection and signal averaging may be used to extend the range and accuracy of measurements of ultrasonic velocity and attenuation. Significant improvements in signal‐to‐noise ratio are obtained by averaging a coherently detected echo train in a signal averager such as a multichannel analyzer or boxcar integrator. A standard circuit of this type is described and analyzed. Comparison of coherent detection and rectification shows the inherent advantages of coherent detection for signal‐to‐noise enhancement.

ISSN:0034-6748    

DOI:10.1063/1.1684032

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Apparatus has been developed for the measurement of PVT properties of gases to pressures of 10 000 bars and to temperatures of 400°C. The apparatus is described, the corrections which must be applied to the raw data discussed, and some illustrative results presented.

ISSN:0034-6748    

DOI:10.1063/1.1684033

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

In this article, we describe a digital solid state double boxcar of infinite holding time and very high linearity. It uses a Hewlett‐Packard (HP2212 A‐M3) voltage‐to‐frequency converter (VFC) whose output is accumulated on a running counter, thereby providing signal averaging with an infinite holding time. The combination of FET signal gates with zero offset and the highly linear VFC results in a linearity of better than ±0.01% over an input range of ±1.0 V, which is a considerable improvement over that available with other digital boxcars. Integrated circuit pulse generators of high stability provide gating times from a fraction of a microsecond to many seconds. A unique monitoring system allows ease of adjustment with a simultaneous ``master'' display of all gating and signal functions. Other features of this boxcar are extreme compactness, low cost, and very high stability.

ISSN:0034-6748    

DOI:10.1063/1.1684034

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

In this paper we describe a compact multipurpose counter whose design is based on the use of plastic integrated circuits. The circuit contains about $90 worth of semiconductor components and is very easy to wire; nevertheless, it is extremely versatile. It consists of dual 107and 105counters which can be used separately as two counters, or in series as a single 1012events counter. Frequencies up to 10 MHz can be read to the accuracy of the crystal used (typically better than 0.005%). Time intervals can be measured—either the width of a single pulse or the time interval between the positive (or negative) slopes of two pulses. The circuit can also be used as a digital integrator, since the average count of pulses in a series of numerous pulse train events can be automatically evaluated after 10, 100, 1000, or 10 000 events.

ISSN:0034-6748    

DOI:10.1063/1.1684035

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A technique is described for making pure lithium targets in the range of 100 &mgr;g/cm2by encapsulation in a sputtered nickel film. The oxygen impurity is about 2%.

ISSN:0034-6748    

DOI:10.1063/1.1684036

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Measurements of the counting rates (∼103to 104counts/sec) of continuous‐channel electron multipliers mounted in an electrostatic analyzer responding to a monoenergetic beam of electrons, while operating in a vacuum chamber at a pressure ∼3×10−6Torr attained with an oil diffusion pump, display a degradation of their gain (fatigue) which is proportional to the accumulated counts. The useful lifetime of these devices when employed with fixed‐threshold pulse amplifiers is defined here as the accumulated counts until gain degradation has produced a reduction of the counting rates to 15% of the initial responses at an operating bias voltage of 4000 V and constant stimuli. The lifetimes of these particle detectors in this laboratory environment are ∼1010counts or, for example, an average counting rate of 300 counts/sec for one year. Comparison of this laboratory lifetime with the responses of similar instrumentation which has been flown on the earth satellites OGO's 3, 4, and 5 and IMP 4 demonstrates that the expected lifetimes for these electron multipliers in a spaceflight environment are several years. Efficiencies of an electron multiplier for counting monoenergetic electrons over an energy range ∼60 to 50 000 eV are also presented.

ISSN:0034-6748    

DOI:10.1063/1.1684037

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A cryostat is described for irradiations with electrons at liquid helium temperatures and subsequent photoconductivity and infrared absorption studies in the range from 20 to 400 K. Heat is removed from the sample by conduction through a copper tail touching the bottom of the liquid helium container. A mechanical ``switch'' enables the thermal separation of the sample assembly from the helium bath during the annealing studies. A rotatable outer‐tail piece permits irradiation with electrons through aluminum windows avoiding damage to the optical NaCl windows. The beam dosimetry and monitoring equipment are described in detail.

ISSN:0034-6748    

DOI:10.1063/1.1684038

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A new design of a low pressure sputtering system of magnetron type is described. The optimum sputtering conditions are discussed in relation to the system. It is shown that this system is able to produce uniform thin films with good reproducibility, and especially to produce a metal oxide film by reactive sputtering. Some typical configurations are presented for use in the laboratory and on a production scale.

ISSN:0034-6748    

DOI:10.1063/1.1684039

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A system is described that employs infrared radiometry and electron beam techniques to raise sequentially the temperatures of small metal targets from a level near liquid nitrogen to the 100 to 600°C range. The system is automatic and achieves the selected temperature with an over‐all error less than 0.5°C.

ISSN:0034-6748    

DOI:10.1063/1.1684040

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A rocket borne spectrometer system sensitive to 6–80 keV photons is described. The system includes a shutter‐collimator that makes it possible to measure the contribution to the background due to charged particle interactions in the mass of the rocket payload. Also described is a detector rotation mechanism that allows the look angle of the detector with respect to the rocket axis to be changed during flight.

ISSN:0034-6748    

DOI:10.1063/1.1684041

出版商:AIP    

年代:1969

数据来源: AIP