Bibliography

V. Bochkarev, I. Keirim-Markus, M. Lvova, Ya. Pryslin, Measurement of the Activity of Beta- and Gamma-Radiation Sources. Publishing House of the Academy of Sciences of the USSR, 1953, 242 pp. Price 10 rubles 30 kopecks.

As the authors of the book under review indicate, in writing it they set themselves the task of creating “a short manual for scientific workers, engineers, and other specialists conducting work connected with the measurement of the activity of radioactive isotopes, but having no special training in the field of nuclear physics.” The need for a manual of this kind has long been felt, and one can only regret that the publication of the book under consideration has been so greatly delayed.

A considerable number of manuals devoted to the technique of working with radioactive isotopes have appeared abroad; some of these books have been translated into Russian. For understandable reasons, however, translated experimental manuals cannot fully satisfy our reader.

The experimental difficulties encountered by an investigator measuring the activity (especially the absolute activity) of radioactive preparations are quite numerous and varied. The purpose of the present manual is to draw attention to these difficulties and to indicate ways of overcoming them. Since, in the practice of $\alpha$-radiation, comparatively few are used, only $\beta$- and $\gamma$-emitters are considered.

In the first chapter—“Radioactivity”—a brief survey is given of information on nuclear physics needed in order to obtain a clear idea of the properties of radioactive atoms. Information on the structure of the atom and the atomic nucleus, on the basic properties of radioactive elements and their radiations, and on methods for obtaining radioactive isotopes is presented concisely. Both the selection and the presentation of this material differ little from what may be found in previously published manuals.

The second chapter—“Methods of Measuring Activity”—is, in our opinion, the most valuable in the book. The operation of ionization chambers and counters is analyzed briefly but clearly. At the same time, in keeping with the general character of the book, emphasis is placed not on the subtleties of the theory of the mechanism of operation of these instruments, but on the practical aspects of working with them. The question of introducing various corrections in measurements with counters operating in combination with a standard counting installation is considered in detail. Apparently, by chance, the question of introducing corrections for isotope decay is not touched upon. At the end of the chapter, two examples of determining the absolute activity of sources of $\beta$-particles ($\mathrm{P}^{32}$) and $\gamma$-rays ($\mathrm{Cs}^{134}$) are discussed in detail.

The third chapter—“Measurement of the Activity of Certain Radioactive Isotopes”—is, as it were, a practical appendix to the first two chapters. It specifically examines methods for measuring the activity of a number of the isotopes most frequently used in practice and gives the necessary information for this purpose on methods of obtaining each given isotope,

scheme of its decay and the properties of its radiation. This chapter is valuable because the authors not only draw the researcher’s attention to those features of measurement which are characteristic for each isotope, but also provide ready-made working tables and graphs that facilitate the processing of measurement results. In particular, a large number of tables are given for determining the dependence of activity on decay time.

In the fourth chapter some questions of safety technique connected with work with radioactive isotopes are considered. A large number of examples are given for determining doses from sources of known activity, for determining the thickness of protective screens, safe distances, permissible working time, etc., and the necessity of taking biological factors into account when determining the above-mentioned quantities is noted.

On the whole, the book may be regarded as successful. It is written in a concise and clear language. The material is divided into short paragraphs supplied with subheadings, which make it possible to orient oneself quickly in the contents of the book. The chief merit, which advantageously distinguishes the book under review from most of its predecessors, consists in the fact that, as a rule, the most important propositions and formulas are made concrete, i.e., supplemented by working tables or graphs and illustrated by numerical examples, etc. Such a method of exposition is not only desirable, but quite necessary in a book intended for the non-specialist. Unfortunately, the authors do not always adhere to this method. In some cases the limits of applicability of the formula presented are not indicated, or the dependence of one quantity or another on particular measurement conditions is not disclosed. In other cases, information is given which can find application in practical measurement conditions only with considerable reservations. We shall give several examples.

For determining the geometrical efficiency of an end-window counter, the usual formula \(K = 1/2(1 - \cos \alpha)\), suitable for a point source, is given. Meanwhile, in practice, the dimensions of the source and of the counter window are usually of the same order. Naturally, the reader would like to know to what extent the formula presented is applicable to non-point sources and how the necessary correction should be calculated in that case. There are no such data in the book.

The sections devoted to introducing corrections for absorption and self-absorption of \(\beta\)-rays, in our opinion, are written without the caution needed in such a rather delicate question. Thus, for example, it is asserted that the correction for absorption can be approximately determined by the formula

\[ K = 2^{-\frac{l_{\mathrm{eff}}}{d_{1/2}}}, \]

and it is only mentioned in passing that “the shape of the absorption curve depends somewhat on the geometrical conditions of the experiment” (p. 39). In reality, however, the form of the absorption curve can depend very strongly not only on the geometrical conditions of measurement, but also on the nature of the directionality of the incident rays. Therefore a formula for taking self-absorption into account, based on the assumption of an exponential law, in many practical cases proves completely unsatisfactory. This also follows from Fig. 36 given in the book, from which it is seen that the curve of the dependence of the self-attenuation coefficient on the thickness of the source has a maximum (we note, however, that the explanation of this phenomenon offered in the book is so unclear that it will hardly be intelligible to a reader unfamiliar with the essence of the matter). Although experimental methods of determining corrections for self-absorption are also described, it seems to us that, in general, too much attention is devoted to the method of introducing corrections for absorption and self-absorption by means of formulas: in all the examples, these corrections are determined by formulas. Finally, let us note that, since the form of the self-absorption curve depends on

the nature of the carrier and on the form and method of preparation of the specimen, consideration of this question in the book would seem desirable.

The treatment of the question of determining the statistical errors of measurements is perhaps too general. A formula is given for determining the statistical error from a specified number of measured pulses, whereas in practice the investigator is faced with the task of determining the minimum number of pulses from the specimen and the background that will ensure a specified relative accuracy. It would have been expedient to include the corresponding table in the book.

A certain abstractness and compilatory character of the exposition reduce the practical value of the book. Nevertheless, it may be considered that the authors have accomplished their task by creating a book that will be useful to many investigators and, above all, to those who, while directly engaged in measuring the activity of radioactive sources, are not physicists.

L. Bell