摘要:

A brief review is presented of simple forms of electrical layout which are used in resistivity investigations on the upper surface of a two-layered medium of which the crust of the earth is assumed to be an example. The associative formulas for resistivity are given.The necessity for equalization in magnitudes of the source and the sink in all experimental methods of resistivity investigation is emphasized in order to be in accord with the basis of development of the formula, and in order to eliminate experimentally pseudo anomalies which may appear in homogeneous media.Formulas are developed for use in conjunction with experimental results obtained by the use of drill holes whereby the source and sink are embedded in a two-layered medium. Distinction is made in the cases where the source and sink are remote from, or are in the neighborhood of, the plane of separation of the layers.Some experimental results on the values of the interbowl résistance,R, are presented in comparison with the values ofRthat would be obtained from a medium of two homogeneous layers of a suitably chosen resistivity ρ. The local anomalies in these layers appear clearly.

ISSN:1923-4287    

DOI:10.1139/cjr50a-001

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

An experiment is described which tests the hypothesis that the cosmic ray meson with a mean life of 2.2 μsec. decays into an electron and a photon. Geiger counter trays are used to select mesons incident on a graphite block, and to detect decay products emerging from the graphite. The electronic circuits record delayed coincidences that correspond to a decay event occurring between 0.6 and 5.3 μsec. after a meson is stopped. The absence of delayed coincidences of a type that could be attributed to the simultaneous emission of an electron and a photon, each of ~ 50 Mev., shows that the above hypothesis of the meson decay process is incorrect. The experiment also demonstrates the absence of a hypothetical unstable neutral meson among the decay products.

ISSN:1923-4287    

DOI:10.1139/cjr50a-002

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

In this paper is described a new calorimeter for the measurement of specific heats at high temperatures, by the adiabatic method. The advantage is that the specific heat at a definite temperature can be determined by a measurement taken over a small temperature interval, with a precision of 1% or better, throughout the range 400 °C. to 800 °C. This permits a study of specific heat anomalies in this range.

ISSN:1923-4287    

DOI:10.1139/cjr50a-003

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The atomic heats of chromium, manganese, and cobalt have been measured up to 800 °C. by the adiabatic method described in Part I of this series. The specific heat of chromium is regular from 0° to 800 °C. The measurements with manganese show the sharp α−β transition at 717 °C., with a latent heat of 450 cal. per mole. Typical supercooling occurs on the reverse transition. Cobalt shows an anomaly due to a gradual transition, which is known to be a change in crystal form. The new data obtained permit a comparative discussion of the atomic heats of the transition metals, chromium to nickel. All these have valuesCv > 3Rat high temperatures. After allowing for the effects of ferromagnetism, the excess specific heats of cobalt and nickel are accounted for by the conduction electrons. This is not true for chromium and manganese, for which metals there must be some additional source of internal energy. It is tentatively suggested that these two metals may have antiferromagnetic transitions at temperatures above 800 °C.

ISSN:1923-4287    

DOI:10.1139/cjr50a-004

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The preparation of a polonium–beryllium sandwich containing 2.1 c. of polonium is described. The source emits 2 × 106neutrons per second and its γ radiation is approximately equivalent to that of 0.2 mgm. radium in equilibrium with its decay products. Polar diagrams for the angular distribution of the fast neutrons are given. Emission data for two similar neutron sources, containing 3.2 and 3.5 c. polonium respectively, are given.

ISSN:1923-4287    

DOI:10.1139/cjr50a-005

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The paper describes the apparatus used to stabilize the magnetic field of a large electromagnet. A rotating coil placed in the magnetic field generates an alternating voltage which is proportional to the strength of the field. Variations in this rotor voltage are used to control the current supplied to the electromagnet in such a manner as to keep the field constant. By means of a calibrated held control the magnetic field strength may be adjusted to any value between 500 and 6000 gauss. The current for the electromagnet is obtained by rectifying 60 cycle alternating current in a full wave, thyratron, rectifier circuit. This current is controlled by a pulse circuit which governs the fraction of each cycle during which the thyratrons are conducting. The stabilization at any held setting is better than 1 part in 1000.

ISSN:1923-4287    

DOI:10.1139/cjr50a-006

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

A magnetic resonance accelerator for electrons is described which was constructed on the principles suggested by Veksler. A constant magnetic field and applied frequency are employed, the frequency of the accelerating radio-frequency field being 2800 megacycles per second. Final energies of five million electron volts are obtained.

ISSN:1923-4287    

DOI:10.1139/cjr50a-007

出版商:NRC Research Press    

年代:1950

数据来源: NRC