摘要:

Measurements of the absorption of gamma-rays from Co60and radium have been made in a number of materials. Variation of absorption coefficient of the gamma-rays from radium with thickness of lead absorber is in agreement with recent experimental determinations. The gamma-rays from Co60are approximately monochromatic and are therefore suitable for testing theoretical absorption formulae. The absorption coefficient per electron for materials of atomic number equal to or less than that of aluminium was in agreement with the Klein–Nishina formula, assuming the cobalt radiation to consist of two lines at 1.10 and 1.30 Mev. respectively. The photoelectric absorption coefficients per electron for heavy elements are in good agreement with the theory developed by Hulme, McDougall, Buckingham, and Fowler. This coefficient varies approximately asZ3.5.

ISSN:1923-4287    

DOI:10.1139/cjr47a-026

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

The relation between the power received by a short, rectangular, electromagnetic horn, and its angular position in a plane electromagnetic field can be calculated, for rotation in the plane of the electric vector, from ordinary optical theory by assuming that the aperture produces at the throat a Fresnel diffraction pattern appropriate to the angular position of the aperture. Experimental results for four horns of slant lengths 25, 50, 100, and 176 cm., but all of the same aperture, 10λ to a side at a wave length of 3.2 cm., are in good agreement with the theoretical predictions at angles up toradian from the axis, for slant lengths down to 50 cm. but not down to 25 cm.

ISSN:1923-4287    

DOI:10.1139/cjr47a-027

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

A method is described for deducing electron trajectories from optical measurements made on the electron microscope. A device for centring and changing apertures while the microscope is in operation is described. The choice of the size and position for diaphragms is discussed, together with other factors involved in their use.

ISSN:1923-4287    

DOI:10.1139/cjr47a-028

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

A cold cathode proton source operating at about 200 v. at a pressure of a few microns is described. The discharge is essentially similar to that of a Philips vacuum gauge. The characteristics of the discharge the ion extraction, and the proton production have been investigated. The addition of 10% of oxygen to the hydrogen increased the proton content of the ion beam from 10 to 50% while introducing only about 1% of oxygen and other foreign ions. The ionization processes are discussed.

ISSN:1923-4287    

DOI:10.1139/cjr47a-029

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

An apparatus for measuring the thermal conductivity of metals in the temperature range 0° to 800 °C. is described. The method utilizes unidirectional heat flow in a cylindrical sample in a vacuum. The advantages of the method are outlined and a comprehensive analysis of possible errors in the measurements is included. Measurements on Armco iron indicate that results with an absolute error of less than 2% may be obtained. The results of measurements on a sample of Armco iron gave thermal conductivities of 0.1819 c.g.s units at 0 °C. and 0.0698 c.g.s. units at 800 °C. A change in slope of the thermal conductivity–temperature curve was found at a temperature of approximately 375 °C., and is tentatively attributed to the presence of 0.03% nickel impurity.

ISSN:1923-4287    

DOI:10.1139/cjr47a-030

出版商:NRC Research Press    

年代:1947

数据来源: NRC