摘要:

A small boron trifluoride chamber is used to obtain the spatial distribution and density integrals of thermal neutrons produced by a source in aqueous solutions of compounds of lithium and boron. The effects of the finite size of the boron chamber are minimized by adjusting the concentrations of the solutions so that the mean life of thermal neutrons is the same in both. The scattering mean free paths are also almost identical. The final result isTaking σB = 705 × 10−24 cm.2per atom, σLi = (66.8 ± 1.0) × 10−24 cm.2per atom.

ISSN:1923-4287    

DOI:10.1139/cjr47a-009

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

It can be shown from the masses involved that the reaction O17(n, α) C14should be exothermic by 1.72 Mev., and should therefore occur with thermal neutrons. As an attempt to detect the reaction an investigation was made of the pulse spectrum produced when an ionization chamber containing oxygen was placed in a flux of thermal neutrons. The pulses were amplified and then counted in a series of energy bands by means of a kicksorter. Two oxygen samples were compared, one being enriched (three times normal), and the other impoverished (0.5 times normal), in O17. Differences between runs with these two gases showed a considerable number of pulses between 1 and 2 Mev., with a maximum at 1.4 Mev. Reasons are given for assigning these pulses to the above reaction, including considerations of the possibility that other exothermic neutron reactions occur. By comparing the number of pulses with the number produced by N14(n,p) C14when the chamber contained air, a value of (1.9 ± 0.5) × 10−28 cm.2for the cross-section for the O17(n, α) C14reaction in ordinary oxygen was deduced. This gives a cross-section of (0.46 ± 0.11) × 10−24 cm.2per atom of the pure isotope O17. The effect measured is about 20% of the total thermal neutron capture cross-section that has been reported for ordinary oxygen.

ISSN:1923-4287    

DOI:10.1139/cjr47a-010

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

By measuring the velocity of various types of elastic waves in a solid it is possible to deduce Young's modulus and Poisson's ratio. Longitudinal, extensional, and Rayleigh wave velocities were measured in ice, the first by resonance in a rod and the other two by a pulsing technique. The value obtained for Young's modulus was 9.8 × 1010 dynes per cm.2and for Poisson's ratio was 0.33.

ISSN:1923-4287    

DOI:10.1139/cjr47a-011

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

This paper attempts to show:(a) The nature of the basic assumptions made either explicitly or implicitly by L. de Broglie in arriving at the fundamental formula,, of wave mechanics, and that at least some of these assumptions are open to criticism.(b) That it is a little too hasty to regard as demonstrated the non-localization of photons or electrons in motion and the lack of determinism with respect to them.(c) That the presuppositions which lead to the 'relations of incertitude' involve highly arbitrary elements and these 'relations' are read into or arbitrarily imposed upon the physical world rather than really found to be in it.(d) That it is an unwarranted claim that the new mechanics can contribute to the solution of the age-long philosophical problem of free will.(e) That it is possible to render the foundations of wave mechanics logically independent of the theory of relativity.

ISSN:1923-4287    

DOI:10.1139/cjr47a-012

出版商:NRC Research Press    

年代:1947

数据来源: NRC