摘要:

A multichannel circuit has been devised for measuring short time intervals directly with a sequence of timing circuits. The output is in the form of counts per time interval with one and only one output count per pair. Time intervals can be measured from less than 5 psec up to any length of time for which it is practical to build a delay line. With coaxial lines used as delay lines, the timing standard deviation in theNth channel is (1.4+0.36N)½psec. The temperature drift of a single channel without temperature compensation is 5 psec/°C and is not cumulative in a long chain of circuits.

ISSN:0034-6748    

DOI:10.1063/1.1720016

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A description is given of a compact, low cost expendable acoustic transponder suited for use in the deep ocean. A unique signal recognition circuit is employed that gives a very high ratio of correct answers to false replies when exposed to the wide variety of noises found in the sea. A very low battery drain permits a relatively small supply to last for a year or more, thus resulting in an instrument that can be easily handled at sea.

ISSN:0034-6748    

DOI:10.1063/1.1720017

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

The spatial waveform of the azimuthal electric fieldE&thgr;of the Stix coil is investigated. Methods are developed to improve theE&thgr;waveform by making it more nearly sinusoidal. Varying the spacing between individual coil turns in the coil section, along with the use of a ``squirrel cage'' type Faraday shield, is found to give a more nearly sinusoidal waveform. The effect of a number of Faraday shields on theE&thgr;waveform is also presented and it is found that certain types of shields, notably the single slit copper cylinder shield, introduce distortions into the accelerating (E&thgr;) field. The efficiency of these shields in reducing the longitudinal electric fieldEzis reported. Several are found to be efficientEzshields, except for a Faraday shield placed outside the Stix coil. The effect of Faraday shields on the equivalent circuit parameters of the Stix coil is also determined, and the variation of these parameters among the various shields is tabulated.

ISSN:0034-6748    

DOI:10.1063/1.1720018

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

The absorption of infrared light by water is used to measure depth. A collimated beam of light from an incandescent filament source is projected through the water from below, filtered, and detected by an infrared sensitive phototube. The quantitative performance of the gauge is assessed, and the effects of refraction and reflection at the the free surface are discussed. A circuit that linearizes the exponential dependence of the phototube output on depth is described. The sensitivity of the gauge and linearizing circuit is determined by calibration to be about 0.05 V/cm, and the smallest measurable wave amplitude, corresponding to unity signal‐to‐noise ratio, is about 0.07 mm. The accuracy for absolute depth measurement is about ½ mm.

ISSN:0034-6748    

DOI:10.1063/1.1720019

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

This report describes a 20 channel ``stepper'' magnet assembly designed to cause the incoming Bevatron particle beam to scan across the 1.83 m hydrogen bubble chamber in discrete steps. The purpose of this device is to avoid superimposing tracks. Stepping was triggered by an ``events'' counter placed in the beam. The system was built with low voltage, silicon controlled rectifiers. Magnet pulsing was accomplished in two parts, rapid rise of field was produced by a fast circuit and pulse length was maintained by a slow circuit. Cost was approximately $15 000, exclusive of the surplus components.

ISSN:0034-6748    

DOI:10.1063/1.1720020

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A cylindrical spark chamber consisting of only two electrodes, the radii of which differed by a factor of more than 3, has been successfully operated while surrounded by grounded conductors, one of which was situated at a distance of only 4.5 mm from the sensitive volume of the chamber. Very thin and straight tracks were obtained which followed the particle trajectory up to large inclinations from the normals to the surface of the electrodes.

ISSN:0034-6748    

DOI:10.1063/1.1720021

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Cˇerenkov light flashes produced by cosmic rays traversing the window of an end‐on photomultiplier create a fundamental noise limitation that cannot be reduced by cooling the tube. Although the cosmic ray pulse rate is only 1 or 2 cm−2/min, the individual pulses may be hundreds of times larger than single electron pulses. Thus in dc or charge integration photometry, cosmic ray noise can exceed thermionic dark current noise at temperatures as high as +10°C. These assertions are based on the observed behavior of EMI 6256 and 9558 tubes. The implications for photometry of faint astronomical sources are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1720022

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

The measured phenomenon modulates in intensity a horizontal line on a CRO screen. The vertical position of this line is electrically linked with the position of the detector (e.g., photomultiplier). If the phenomenon is repeated many times while the detector slowly moves, the individual lines fuse into an intensity modulated space‐time diagram, similar to a TV picture. The method quickly provides accurate and full information of even very complicated and fast wave phenomena, and increases the signal‐to‐noise ratio by summarizing many independent measurements into a single picture. Examples of the use of the method for measurements of ionization waves in a discharge plasma are given.

ISSN:0034-6748    

DOI:10.1063/1.1720023

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Design equations are developed for three types of charging circuits commonly employed in line type pulsers. Parameters determined by these equations lead to systems which optimally utilize the power source. Both resistive and inductive charging networks are considered.

ISSN:0034-6748    

DOI:10.1063/1.1720024

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Conventional coherent illumination provides the interference at high orders necessary for microtopography. However, the resulting interferogram is not a true, undistorted contour map of the specimen, nor is there any direct method of assessing the distortion. In addition, coherent illumination gives poor resolution, and when vertical illumination is used reflections in the objective reduce the contrast. These problems are all ameliorated by using incoherent illumination limited to a small range in angle relative to the plane of the reference reflector but unconfined in azimuth, i.e., the illumination produced by an annular source in the back focal plane of the illuminating lens.

ISSN:0034-6748    

DOI:10.1063/1.1720025

出版商:AIP    

年代:1966

数据来源: AIP