Geophysical Abstracts 152 January-March 1953

GEOPHYSICAL ABSTRACTS 152, JANUARY-MARCH 1953 43
RADIOACTIVITY
INSTRUMENTS AND METHODS OF OBSERVATION
14324. Healy, J. W. Measurement of natural radioactivity background:
Nucleonics, v. 10, no. 10, p. 14-19,1952.
This is general description of the techniques of measuring natural radio­
activity in the atmosphere, water, and soil. M. C. R.
14325. Heydenrych, J. C. R., and du Plessis, C. B. M. Instruments for radio­
activity and temperature measurement in narrow boreholes: Easa,
v. 9,11 p., June 1952 [Seen as reprint only].
The instrument consists of a temperature feeler unit, radioactivity pick-up
unit, temperature indicator, and radioactivity indicator and recorder. The
temperature feeler unit consists of a steel wire stretched and rigidly fixed at two
ends to a brass container. Increased temperature causes expansion of the
cylinder, greater tension on the wire, and an increase in the frequency of the
continuous signal being transmitted up the wire. The radiation pick-up unit
transmits a constant frequency signal modulated to zero by pulses from a
Geiger-Miiller counter. The instrument can be lowered to 10,000 ft. or more
and will withstand water pressures of as much as 5,000 pounds per square inch.
Outside dimension is l%e in. A circuit diagram is given. M. C. R.
14326. Kanne, W. R. Monitoring gas for radioactive Xenon. U. S. patent
2,625,'657, granted January 13, 1953. 8 claims. Assigned to United
States of America, represented by U. S. Atomic Energy Commission.
14327. Bulashevioh, Yu. P. K teorii neytronnoge karottazaha [On the theory of
neutron logging] : Akad. Nauk SSSR Izv., Ser. geofiz. no. 3, p. 31-36,
1951.
This is a supplement to a previous article on the theory of neutron logging of
drill holes (see Geophys. Abs. 10624). Discussed here are the slowing down
of rapid neutrons and the effect of this phenomenon on the widening of the
volume of scattering of thermal neutrons and the increase of the zone of capture
in different formations. Rapid neutrons are more often met in geophysical ex­
ploration, because they are found, for instance, in logging of holes filled with
water. The case of dry drill holes, treated previously, is rather exceptional.
A solution of the problem of the diffusion of thermal neutrons is given. Slow­
ing down of neutrons and the increase of scattering are computed under the
simplifying approximations that these phenomena are determined only by atomic
weight and the number of atoms in a unit volume of the formation. The influence
of crystalline and chemical bonds on the behavior of high energy neutrons is
neglected.
The results of computations are presented in graphs with different curves
corresponding to different media of scattering, such as limestone, gypsum, sands
of varying moisture content, oil and others.
The influence of the length of the detector on the shape of the curves is also
discussed and recommendations are given for optimum conditions. 8. T. V,