摘要:

A description is given of a neutron time‐of‐flight spectrometer used for energies up to 140 Mev. A 20‐m&mgr;sec neutron pulse is obtained by electrostatic deflection of the internal proton beam of the cyclotron onto a thick aluminum target. By timing the neutrons over a 26‐meter flight path an energy spread of 4.2% at 15 Mev is obtained rising to 14% at 140 Mev. The advantages of the technique and possible improvements are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1715717

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A systematic investigation of the optimum conditions for the design and operation of a gas scintillation counter has been made. The gases studied were xenon, krypton, argon, helium, and various gas mixtures. Both a 6292 and a quartz window K1306 phototube were used with and without quaterphenyl as a wavelength shifter. Under optimum conditions an energy spread of less than 4% is obtainable for the Po210&agr; particles. The application of the gas scintillation counter as a fast ``slow neutron detector,'' using the reaction B10(n,&agr;)Li7, and its usefulness as a fast fission detector have been examined and discussed.

ISSN:0034-6748    

DOI:10.1063/1.1715718

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

Monoenergetic electrons from an electron accelerator were incident on a thin bare anthracene crystal centered on the photocathode of a RCA 6199 photomultiplier. A linear amplifier and single channel analyzer were used to obtain a pulse height distribution at each energy. The pulse height at the maximum of the distribution is a linear function of the incident electron energy with intercepts of 4.5 and 3.5 kev for 0.060‐ and 0.011‐in. thick crystals, respectively. The pulse‐height distribution could be fitted well with a Gaussian. The data indicate a linear relationship between the square of the full width of the pulse‐height distribution at 1/eof the maximum and the electron energy. The average amount of electron energy absorbed in the crystal required to produce a photoelectron at the photocathode is 1.47±0.09 kev/photoelectron for the 0.060‐in. crystal and 1.32±0.13 kev/photoelectron for the 0.011‐in. crystal.

ISSN:0034-6748    

DOI:10.1063/1.1715719

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A liquid tin solution calorimeter has been constructed for determining the heats of formation of alloy phases from the heats of solution of the alloys and of the pure component metals in liquid tin. The design of the calorimeter is presented, and the experimental procedures and calculation methods are described and illustrated with data from representative runs. These indicate that heats of formation of alloy phases may be determined with an average uncertainty of about ±50 cal/g atom.

ISSN:0034-6748    

DOI:10.1063/1.1715720

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A pendent drop apparatus for rapidly measuring very low interfacial tensions is described. Interfacial tensions as low as 0.001 d/cm have been measured at 25°C in a water‐oil system. These measurements were made possible through the combined use of small drop‐forming tips, long working distance objectives, electronic flash illumination and Polaroid Land film. Examples of measurements on water‐oil systems are given. The apparatus is designed to provide interfacial tension data as a function of temperature. In addition, the method permits the measurement of interfacial tension as a function of the age of the interface.

ISSN:0034-6748    

DOI:10.1063/1.1715721

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

Control of the energy‐dependendent second‐order aberrations in a Mattauch‐type mass spectrometer is made difficult by the absence of a real image between the object slit and the focal plane in this resolving system. By curving the boundary of the magnetic field and by choosing appropriate relations between the magnetic field boundary curvature and the other parameters involved, it is possible to make both of the energy‐dependent second‐order aberration coefficients vanish simultaneously while retaining the advantages peculiar to this resolving system.

ISSN:0034-6748    

DOI:10.1063/1.1715722

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A spin echo apparatus is described which can measure nuclear relaxation effects for narrow resonances, convection and diffusion effects, and in some cases, chemical splittings in liquids. This apparatus is assembled mostly from commercial equipment. Commercial units used are identified, and circuit diagrams are given for specially constructed apparatus. Sufficient design information is given to make possible substitutions and improvements to suit the needs of particular projects. Necessary adjustment procedures are described and the relations of instabilities in the apparatus to instabilities in its components are treated.

ISSN:0034-6748    

DOI:10.1063/1.1715723

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

The characteristics of a thermal‐conductivity gas‐analyzer unit employing thermistors as sensing elements are analyzed theoretically. It is shown that, as a consequence of the fact that thermistors have a negative temperature coefficient of resistance, the sensitivity of the instrument as a function of bridge current exhibits a maximum. The dependence of zero stability on current and cell temperature is approximately related to differences in resistance, temperature coefficient of resistance, and geometry of the reference and sample thermistors. An apparatus suitable for precise trace analyses is described and results obtained with it are presented. It is suggested that the widespread lack of faith in the inherent stability of thermistors for analysis applications is not justified, and has probably been due to insufficient care with current and temperature control.

ISSN:0034-6748    

DOI:10.1063/1.1715724

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A function of two independent variables can be regarded as an image. Using a novel optical technique, the autocorrelation coefficient of such a function is formed as another image. The working principle of the instrument is based on geometrical optics alone, however, the basic equipment was further improved by adopting electronic scanning techniques. Test plates with prescribed autocorrelation functions were made, the equipment was experimentally tested, and was found to operate to satisfaction.

ISSN:0034-6748    

DOI:10.1063/1.1715725

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

The effects of moisture on the electrical properties of ferrites indicate that the electrical characteristics are adversely affected. The problem concerning the methods for the prevention of moisture absorption by the ferrite element has been solved by coating the surface of the ferrite with a thin layer of glass, thereby effecting a hermetic seal. It was found necessary, however, to first sinter a thin layer of finely ground ferrite surface to reduce porosity, which prevents the flowed glass from being absorbed into the porous ferrite. The glass seal has been shown to have good mechanical and thermal shock properties and yet has negligible effect on the electrical properties of the ferrite.

ISSN:0034-6748    

DOI:10.1063/1.1715726

出版商:AIP    

年代:1957

数据来源: AIP