摘要:

A new technique has been developed for producing microspheres uniform in volume and fluorescence or radioactive tracer. Very uniform spheres with selected diameters are produced by introducing one liquid into the center of a moving stream of a second liquid (of differing surface tension) and breaking the core stream into uniform droplets by the action of a piezoelectric transducer. Fluorescent spheres of 10 &mgr; diam have been produced having a coefficient of variation in volume and fluorescence as low as 3.6%. This corresponds to a diameter variation of about 1.5%.

ISSN:0034-6748    

DOI:10.1063/1.1686082

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The performance of open‐structure channel electron multipliers has been investigated in a laboratory simulation of the ascent pressure profile for a typical sounding rocket. The results of this test demonstrate that evacuation of the payload prior to launch is necessary for experiments where stability of response is an essential parameter.

ISSN:0034-6748    

DOI:10.1063/1.1686083

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Quantitative use of a high speed shock tube depends upon the ability to detect the time of arrival of the shock wave at a given position, with a resolution of 1 &mgr;sec or better so that (1) the velocity of the shock wave can be determined and (2) the various instruments attached to the shock tube can be triggered or energized at the proper time. Of the many types of gauges available for detecting the arrival of a shock wave at a given point, ionization gauges are the simplest and are capable of producing higher signal levels without the use of complicated electronic circuitry. For these reasons ionization gauges are usually the preferred shock wave detectors. Their use has been limited, however, by the fact that the range of shock tube operating conditions at which they perform satisfactorily is small. This paper describes a new method of using ionization gauges by systematically adjusting the electronic circuitry to allow for large ranges in shock tube operating conditions. This method should be useful in various applications where ionization gauges are used to detect shock waves.

ISSN:0034-6748    

DOI:10.1063/1.1686084

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

An electromagnetic technique for measurement of particle or material velocity inside an insulator or the free surface velocity of a conductor subjected to plane shock waves is described. The theory of the technique is described and two illustrative experiments are presented and discussed. The relative merits of the technique are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1686085

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A method for determining absolutely the velocity sense of a Mo¨ssbauer spectrum taken in the multiscaler mode is described. It is shown that relative motion of the Mo¨ssbauer source with respect to the absorber naturally leads to a parabolic profile of the absorption spectrum. This parabola is used to determine the sense of the different sections of the spectrum uniquely without reference to a standard asymmetric Mo¨ssbauer spectrum.

ISSN:0034-6748    

DOI:10.1063/1.1686086

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A description is given of a simple device which uses two 15‐power reflecting objectives, mounted in the cell compartment of a Cary 14 or 17 spectrophotometer. Spectra of crystals with surface area as small as 0.1 mm2can be measured in polarized light at temperatures as low as 6 K. The absorption spectrum of a crystal of 9, 10 dimethylanthracene is given as an example.

ISSN:0034-6748    

DOI:10.1063/1.1686087

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A modified spark cutter for cutting metallic crystals is described. A weakly conducting electrolyte is employed instead of a pure dielectric. The cutting rate is faster and the damage caused to the cut surface is considerably reduced.

ISSN:0034-6748    

DOI:10.1063/1.1686088

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A high‐vacuum valve is described which consists of a wedge driven inside a rectangular cavity. The wedge fitted with an O‐ring is moved over the opening to close the valve. The bore of the valve can be up to two times the valve thickness.

ISSN:0034-6748    

DOI:10.1063/1.1686089

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A painted layer of a colloidal dispersion of graphite provides a versatile vacuum system heater.

ISSN:0034-6748    

DOI:10.1063/1.1686090

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The detection efficiency of a high sensitivity, commercial, residual gas analyzer, when used as an atomic beam detector, has been experimentally determined to be 5.5×10−6for a thermal beam of argon atoms.

ISSN:0034-6748    

DOI:10.1063/1.1686091

出版商:AIP    

年代:1973

数据来源: AIP