摘要:

The mathematical theory of neutron chain reacting systems bears considerable similarity to the mathematical theory of quantum mechanics since the Schroedinger equation can be viewed as the equation for an infinitely large chain reactor in which the potential function is replaced by the distribution of neutron absorption cross sections. The chain reactor theory, not being self-adjoint, is somewhat more complicated than the Schroedinger equation theory. Nevertheless, perturbation theory, time dependent theory, and the theory of the stationary, i.e., just critical, state can be stated in much the same way as is done in quantum mechanics.

ISSN:0002-9505    

DOI:10.1119/1.1933268

出版商:American Association of Physics Teachers    

年代:1952

数据来源: AIP

摘要:

Two contemporary engravings showing early electrical experiments are reproduced together with an entertaining account of such experimentation written by Park Benjamin in 1895.

ISSN:0002-9505    

DOI:10.1119/1.1933269

出版商:American Association of Physics Teachers    

年代:1952

数据来源: AIP

摘要:

A qualitatively satisfactory explanation of the rainbow was given shortly before 1311 by Theodoric of Freiberg and Qutb al-dīn al-Shīrāzī, but this work had disappeared shortly before Gilbert was born. The quasi-Aristotelian theory which Gilbert espoused was akin to early medieval ideas according to which rays from the sun are tinged as they traverse a thin dewy vapor and then are reflected to the eye of an observer by a dark cloud or dense object. Gilbert had the happy thought that a spherical magnet might serve as a miniature earth, but he missed entirely the notion of a globe of water as a magnified raindrop. Unaware of the role of the spherical drops in the refraction of solar rays, the fuzzy speculations on the rainbow which Gilbert gave inDe Mundostand in marked contrast to the experimental philosophy which he advocated inDe Magnete.

ISSN:0002-9505    

DOI:10.1119/1.1933270

出版商:American Association of Physics Teachers    

年代:1952

数据来源: AIP

摘要:

An elementary explanation is given of the group theory method using characters to determine the selection rules for the fundamental vibrations of a linear polyatomic molecule. Then the method is extended to indicate how the selection rules for the overtones and summation and difference tones are obtained. Finally, the procedure for determining the number of fundamental frequencies belonging to a particular vibration type is given. The groupsC∞vandD∞hare used as examples in the treatment since they are the only ones involved in the consideration of linear molecules.

ISSN:0002-9505    

DOI:10.1119/1.1933271

出版商:American Association of Physics Teachers    

年代:1952

数据来源: AIP

摘要:

A review of the present status of liquid scintillators is given. The theory explaining the properties of the counters is discussed. Preparation of counters is described and counter characteristics such as emission spectra, response to various nuclear radiations, counting efficiencies, and emission intensities from various scintillating solutions are given. The applications of liquid scintillation counters in various fields of nuclear physics are discussed.

ISSN:0002-9505    

DOI:10.1119/1.1933272

出版商:American Association of Physics Teachers    

年代:1952

数据来源: AIP

摘要:

The classical and quantum-mechanical interactions of molecular dipoles and metallic surfaces are derived and numerical calculations given for several molecule-metal pairs. The results represent the permanent dipole contributions to the total van der Waals interactions. The bearing of the dipole interactions on the problem of adhesion is discussed.

ISSN:0002-9505    

DOI:10.1119/1.1933273

出版商:American Association of Physics Teachers    

年代:1952

数据来源: AIP

摘要:

Using reliable data on thermal conductivitiesK, viscositiesη, and specific heatscv, values of the important ratiof = K/ηcvhave been determined over a wide range of temperature, 80–380°K, for eight gases. For some gases the ratio shows a decrease with increasing temperature and for others an increase. The results and existing theories do not agree on all points. For a monatomic gas, helium,fhas a constant value up to 250°K, agreeing with most theories, but it drops at higher temperatures. One diatomic gas, hydrogen, shows a sharp drop, agreeing very well with Eucken's theory. Another diatomic gas, nitric oxide, shows a rise much sharper than predicted by the theory. Other diatomic and polyatomic gases show large deviations from Eucken's theory, mainly in that experimental values rise while the theory predicts a decrease with increasing temperature.

ISSN:0002-9505    

DOI:10.1119/1.1933274

出版商:American Association of Physics Teachers    

年代:1952

数据来源: AIP

摘要:

The usual choice of an orthogonal set of four plane-wave solutions of the free-particle Dirac equation does not lend itself readily to direct and complete physical interpretation except in low-energy approximation. A different choice of solutions can be made which yields a direct physical interpretation at all energies. Besides the separation of positive and negative energy states there is a further separation of states for which the spin is respectively parallel or antiparallel to the direction of the momentum vector.

ISSN:0002-9505    

DOI:10.1119/1.1933275

出版商:American Association of Physics Teachers    

年代:1952

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.1933276

出版商:American Association of Physics Teachers    

年代:1952

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.1933277

出版商:American Association of Physics Teachers    

年代:1952

数据来源: AIP