摘要:

A Cˇerenkov counter is described for detecting and measuring the energy of x‐rays in the 50‐ to 300‐Mev range. The incident x‐ray produces a photon‐electron shower in a cylinder of carbon tetrachloride, and the Cˇerenkov radiation emitted by the electrons in the shower is a measure of the x‐ray energy. The cylinder of carbon tetrachloride is 12 in. diam by 36 in. long. The Cˇerenkov radiation is measured with seven 5‐in. photomultiplier tubes mounted at one end of the cylinder. The pulse distribution from the counter has a &sgr;/x¯which varies from 0.146 at 217 Mev to 0.216 at 47 Mev. The energy response of the counter is linear up to 217 Mev, the highest energy at which measurements have been made.

ISSN:0034-6748    

DOI:10.1063/1.1746465

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

An alternating‐gradient magnetic spectrometer has been constructed. The spectrometer consists of two magnetic lenses that deflect the analyzed particles through a total angle of 30°. It is able to analyze protons with energies up to 6 Mev and has a solid angle of 0.012 sterad and a momentum resolutionR=p/dp=77 for 0.5‐mm exit slit. The distance between the source and image positions is 85 cm.

ISSN:0034-6748    

DOI:10.1063/1.1746467

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

Improvements have been made in the differential pulse transformer bridge which increase its inherent precision by approximately an order of magnitude and extend its range to measurements with electrolytes of twenty times the concentration previously feasible. A circuit is described which permits study of the errors introduced by polarization and self‐heating when electrolytic conductivity measurements are carried out with rectangular voltage pulses. Also described is an equipment for four‐terminal resistance measurements with single‐voltage pulses, which allows high‐field conductance measurements free from errors caused by contact resistance, self‐heating, and space‐charge accumulation; it has been applied to semiconductors.

ISSN:0034-6748    

DOI:10.1063/1.1746470

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A recorder for oxygen concentration and rate of exchange is described. A polarographic square wave method is adapted to servo‐pen‐recording. Cam‐driven microswitches provide the square potential pattern and also the programed timing on which the rate evaluation is based. A three‐second time resolution in rate reveals transient details unobserved in concentration recording.

ISSN:0034-6748    

DOI:10.1063/1.1746472

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

It is well known that the density of minority carriers in a germanium crystal can be altered near a rectifying contact. The purpose of this paper is to describe a procedure for preparing reproducible and dependable injecting and extracting contact, in order to obtain a good exponential decay or rise curve of minority carriers for determining their lifetimes by the Many bridge method. It is found that the rectifying and ohmic contacts to a single crystal must be considered together.

ISSN:0034-6748    

DOI:10.1063/1.1746474

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

In the calculation of the interaction of radiation from a point source with a body (or conversely, the intensity of radiation from an emitting body at a point in space), a somewhat complex exponential integral must be evaluated. If the interaction in the body is small, however, the integral may be approximated byI=∫Vdv/R2, whereVis the volume of the body andRis the distance from the point to the volume elementdvin the body. This integral is discussed and applied to the case of a cylindrical body. Extensive tables (>12 000 entries) and formulas have been prepared which will enable the reader to determine the value of this integral for a cylinder of any size and any point in space. A discussion of non‐negligible absorption and multiple interactions is also included.

ISSN:0034-6748    

DOI:10.1063/1.1746476

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

The solid angle subtended at a point by any object is determined by the closed contour which outlines the ``visible'' boundary of the object from the point. By transformation of the double integral &OHgr;=∫ ∫ sin&thgr;d&thgr;d[open phi] into a single integral over &thgr; or [open phi] with limits determined by the contour and choice of axes, the solid angle may be simply represented in the important cases discussed as a contour integral. The integration has been carried out on the high‐speed digital computer ORACLE at Oak Ridge National Laboratory. Solid angle tables have been prepared for the case of the circular disk and the entire finite right circular cylinder in terms of cylindrical coordinates. Each table contains in excess of 12 000 entries to six significant figures.

ISSN:0034-6748    

DOI:10.1063/1.1746479

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A quartz and metal seal capable of holding compressed gases at 1500 atmospheres forms the tapered, coaxial transition leading from a standing‐wave detector or from a bridge, into a coaxial condenser. The continuity of characteristic impedance through the seal is sufficiently good to allow accurate measurement of dielectric constant and loss in compressed gases and liquids from low frequencies to 3000 megacycles (&lgr;0=10 cm) in a single cell. The performance is illustrated with isotherms of the dielectric constant of N2O through the critical point. Organic sealing materials are not used. The unit promises to be satisfactory for a wider temperature range than is reported here.

ISSN:0034-6748    

DOI:10.1063/1.1746481

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A new type distillation column similar to a Vigreau column is described which has the indentations perpendicular to the wall of the tube. It was found that the indentations gave optimum performance if at an angle of 90° to the axis of the column. A jig is described which facilitates making indentations in glass tubing so as to result in a high precision of indentation spacing.

ISSN:0034-6748    

DOI:10.1063/1.1746483

出版商:AIP    

年代:1957

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1746488

出版商:AIP    

年代:1957

数据来源: AIP