摘要:

The diffusion of gases through thin‐walled nickel tubing (cathode tubing) has been investigated in the temperature range 200–1000°C. It was found that at the most thoroughly examined temperature of 500°C and at a pressure difference of 1 atmos, hydrogen and deuterium diffuse through this tubing about 2000 times faster than any of the other gases tried. The design of a hydrogen and deuterium leak is described which is easy to construct and to operate. The tubing does not appear to deteriorate because of crystallization as is experienced with palladium tubing.

ISSN:0034-6748    

DOI:10.1063/1.1770969

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

An ion source structure is described which is specifically designed for slow electron ionization of vapors of salts. This may be used up to 550°C. The ion chambers are rapidly interchangeable and memory effects between samples are undetectable over moderate changes in concentration. Some of the characteristics of this source are discussed and its advantages indicated.

ISSN:0034-6748    

DOI:10.1063/1.1770970

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A device embodying Robertson's principle of movable strips is described for performing two‐dimensional Fourier summations of the type&Sgr;H&Sgr;KF(hk)[cos2&pgr;(hX+kY)]without first rearranging them in the form&Sgr;H&Sgr;KF(hk)[cos2&pgr;hX·cos2&pgr;kY−sin2&pgr;hX·sin2&pgr;kY]. The same strips can be used to evaluate sine summations and some three‐dimensional summations directly. The electron density can be readily calculated at selected individual points in the projection. Summations can also be completed by means of masks. The operation of the device, which can accomodate values ofF(hk) = ± (1 to 99),h= −15 to +15,k=0 to 15 forX, Y= 1/36 of the repeat distance, is described, and illustrated by an example.

ISSN:0034-6748    

DOI:10.1063/1.1770971

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

An airborne infrared spectrograph has recently been completed in which electronic techniques are used in novel ways to record 10 spectral samples and the total radiation signal for the wavelengths between 1 and 25 microns. The rapid operation of the sensing and recording systems makes it possible to obtain the complete analysis each 0.08 second together with other pertinent data.

ISSN:0034-6748    

DOI:10.1063/1.1770972

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

This paper describes two new four‐quadrant analog multipliers which have some advantages over other designs which have been reported earlier. A satisfactory balanced modulator which is necessary for both designs is described in some detail. The first multiplier uses a modified double amplitude modulation scheme applying the recent work of Sternberg and Kaufman on the two‐frequency modulation product problem. The test multiplier has a frequency response from dc to 30 kc for either input. The accuracy is ±0.5 percent of full scale at full‐scale output, and ±0.2 percent of full scale at one‐tenth of full‐scale output. The dc drift stability of the output is ±0.15 percent of full scale, and the scale factor stability is ±1 percent of full scale over a period of several hours. The second multiplier uses successive phase modulation and amplitude modulation of a carrier. A description of the method and a discussion of error sources are given. The performance of this multiplier is in general inferior to that of the first.

ISSN:0034-6748    

DOI:10.1063/1.1770973

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A Borelius type isothermal jacket microcalorimeter has been designed and constructed. It consists essentially of a vapor thermostat providing a constant temperature environment about a chamber containing the specimen and measuring device, the latter being a high‐sensitivity differential thermopile. With one set of thermopile junctions kept at constant temperature by contact with the environment, and the other set arranged to vary in temperature with the specimen, a heat effect in the specimen is measured by following the difference in temperature across the thermopile as a function of time. Calibration of the apparatus is carried out by using the Peltier heat developed at the junction of a thermocouple located in an axial hole in the specimen. With an argon atmosphere in the specimen chamber, the limit of detection is a heat flow of 0.003 gram‐calories per hour. The absolute accuracy of the determinations depends upon the particular conditions of a given run, but is usually in the vicinity of 2 to 5 percent.

ISSN:0034-6748    

DOI:10.1063/1.1770974

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A mutual inductance bridge and cryostat are described which may be used to measure susceptibilities from 77°K, with liquid nitrogen, down to adiabatic demagnetization temperatures. In addition to the sensitivity necessary for measurements over such a temperature interval, the apparatus provides the following features: a usable frequency range of 5 kc, for the study of paramagnetic relaxation and paramagnetic specific heat; measurement of longitudinal susceptibilities in fields up to 3000 oersted, and transverse susceptibilities in fields up to 13 000 oersted; a simple method for changing samples with a minimum dismantling of the equipment.

ISSN:0034-6748    

DOI:10.1063/1.1770975

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A diffusion cloud chamber 8 ft long, 4 ft wide, and 5 in. deep has been built and operated successfully for 540 hrs out of a continuous 720‐hr run. Though the actual area is 32 sq ft, the area photographed was 21 sq ft or approximately 2 sq m. A sensitive layer of good quality extending 2½ to 3 in. above the floor was easily maintained. The coolant temperature was held near −67°C and the air above the glass sheet forming the top was held at 30°C. A clearing field of 30 v (top negative) was found desirable to keep the chamber free from general rain. The chamber contained an air and methyl‐alcohol mixture operated at 1 atmos pressure. Tracks in the sensitive region were photographed through the top with the aid of several mirrors. The chamber was used to study the structure of the cores of cosmic‐ray air showers. It is now being used for studies with the bevatron.

ISSN:0034-6748    

DOI:10.1063/1.1770977

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

Apparatus for measuring the moduli and internal friction of solids at temperatures from 1.7 to above 77°K is described. The resonant piezoelectric method with quartz transducers is used. The frequency range is 30 to 450 kc/sec. For calibration variously oriented quartz crystals were measured over this temperature range and the values are given.

ISSN:0034-6748    

DOI:10.1063/1.1770978

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A new compact microtome knife sharpener has been developed which, in its simplest form, provides a semi‐manual method of sharpening blades for standard and ultra‐thin sectioning. Fully mechanized, however, it eliminates the manual element and requires little attention except to see that the grinding powder and its vehicle are maintained. The knife is caused to move back and forth across an oscillating glass plate by means of a motor drive, and a simple mechanism periodically turns the blade over. It rapidly sharpens a blade capable of cutting ultra‐thin sections for electron microscopy while such an edge is unusually fine for paraffin sections. No stropping or other treatment is required.

ISSN:0034-6748    

DOI:10.1063/1.1770979

出版商:AIP    

年代:1954

数据来源: AIP