Letters to the Editor

On the Term “Cyclotron Resonance”

Recently, a very substantial review article by V. N. Lazukin on diamagnetic resonance was published in UFN under the title “Cyclotron Resonance.”* In connection with this title, the article states that although the effect under consideration was originally called “diamagnetic resonance,” this name “did not take root,” because, first, this effect “in essence has little in common with other magnetic resonance phenomena and, second, the mechanism of the phenomenon is related to the mechanism of absorption of high-frequency energy by a charged particle accelerated in a cyclotron.”

It should be noted that the English physicist Dingle and I called the effect predicted independently by us “diamagnetic resonance” precisely because, unlike all other magnetic resonance phenomena, this effect is connected directly and solely with diamagnetism. The American physicists Kittel, Kipp, and Dresselhaus, who then carried out the corresponding experiments, called this effect “cyclotron resonance.” Since then, about a dozen articles have appeared, chiefly by the same authors or their collaborators, in which diamagnetic resonance is called cyclotron resonance.

It is hardly fair to think that henceforth this term should be regarded as established and that it must necessarily be used everywhere and, in particular, in the Soviet literature. How many unsuccessful terms have “taken root” in the Western literature (for example, “annihilation of a pair”) which we, however, do not accept. Consequently, in the present case as well we must first of all clarify which of these two names, “diamagnetic resonance” or “cyclotron resonance,” satisfies the requirements of science.

I should like to express my considerations on this matter.

The name “cyclotron resonance” recalls the fact that a more or less similar process is used in one type of accelerator—the cyclotron. But in physics it has not hitherto been customary to form scientific terms in this way. After all, we do not say “transformer induction,” although electromagnetic induction is used in a transformer. Nor do we say “electric-kettle heating,” although the Joule effect is used in an electric kettle. Nor do we say “thermometric expansion,” although thermal expansion is used in a thermometer. Why, then, should we form the term “cyclotron resonance” in so strange a manner?

The cyclotron is one of the first accelerators of charged particles in the history of science. In a few decades it will probably be replaced by entirely different kinds of accelerators. The cyclotron will then disappear from the scene and become merely a museum exhibit. And the word “cyclotron” will then lose its real meaning for contemporaries, all the more since this extremely unfortunate coinage (kyklos—circle, tronos—throne) is in itself devoid of any meaning.

Upon seeing the name “cyclotron resonance,” a reader not versed in history will then wonder what “cyclotron” means. And one will have to explain to him that once, they say, there existed such a device, which so impressed people’s minds that physical phenomena began to be named after it. Meanwhile, the designation “diamagnetic resonance” can remain in physics forever, since this term will remain comprehensible to any physicist at any time. Therefore I think that we should call this effect diamagnetic resonance, not cyclotron resonance. I am not at all guided in this matter by authorial vanity and am ready to accept any other name for this effect (if one is proposed), but this term must necessarily proceed from the physical characteristic of the phenomenon, and not from the name of the construction of some device. At a meeting of my “Conference on the Physics of Magnetic Phenomena” in Moscow I raised this question, and Prof. A. F. Kipp (USA), who was present at the meeting, not only

* UFN LIX, 553, 1956.

agreed with my arguments, but also promised henceforth not to use the term “cyclotron resonance.” I hope that Prof. Kipp will keep his promise. It is all the more desirable that in Soviet literature the scientific term “diamagnetic resonance” should henceforth be used, and not the strange nickname “cyclotron resonance.”

Ya. G. Dorfman

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Professor Ya. G. Dorfman addressed a letter to the editors of UFN in which he protests against the name “cyclotron resonance” for an effect that he had predicted at one time.

This letter may create the impression that I alone—the author of a brief review article in UFN—insist on the indicated name, while most physicists either already call, or propose in the future to call, the effect by its original designation: “diamagnetic resonance.” It also follows from the letter that my assertion that “the name originally given did not take root” is my own invention and that, in using the term “cyclotron resonance,” I uncritically transfer American terminology into Soviet physics literature.

In reality, the situation is not at all so simple. In the course of working on the article I thought a great deal about terminology, and I adopted the term “cyclotron resonance” not without hesitation. Nevertheless, I did so and did not replace the new term with the old one during the proofreading correction, although I was aware of Prof. Ya. G. Dorfman’s views on this question.

As a strange, at first glance, but not very successful term, “cyclotron resonance” has indeed become more widespread than the former designation “diamagnetic resonance,” above all among physicists engaged in the study of semiconductors and radiospectroscopy. Without referring to foreign data*, I would like to note that Soviet physicists—specialists in semiconductors for the effect under discussion—use only the former name and do not use the latter at all. Thus, at the All-Union Conference on Semiconductors (Leningrad, November 14–20, 1955), which brought together more than 1100 Soviet physicists and more than 50 scientists from the countries of the People’s Democracies, all speakers who touched in one connection or another on cyclotron resonance absorption called it only by this term. This terminology found expression also in the official documents of the conference. In the resolution adopted at the concluding plenary session of the conference, in section 3 (on tasks in the field of semiconductor research), we read:

“(g) preparation of investigations on paramagnetic, cyclotron, and other types of resonance phenomena in semiconductors...”

It should be noted that the conference was headed, and the organizing committee chaired, by Acad. A. F. Ioffe, whom it would be difficult to suspect of not understanding the essence of physical phenomena in semiconductors or of careless handling of terminology. The author of these lines took part in the work of the conference organizing committee, but it can hardly be assumed that he inspired the use of unsuccessful terminology in an official document adopted by a numerous and highly authoritative gathering of physicists.

Furthermore, the term “cyclotron resonance” is generally accepted in the plans of scientific institutions engaged in the study of semiconductors.

Thus, this term has become generally widespread among physicists and has been officially recognized as the only designation for the given phenomenon.

Under these conditions it would hardly have been appropriate if the author of the review had not noted that the name originally given did not take root, while the designation “cyclotron resonance” became more commonly used.

Of course, it was not only these formal considerations that compelled the author of the review to adopt a term that he himself does not consider very successful.

The situation that arose with the name of the effect predicted by Prof. Ya. G. Dorfman did not arise by chance. In science it often happens that the terminology initially adopted by the author does not take root. Thus, for example, the term “photomagnetic effect,” proposed at one time (to denote magnetic resonance absorption), did not take hold in science because another term was found, one that more precisely reflected the physical essence of the phenomenon.

Can the term “diamagnetic resonance” be considered more successful than “cyclotron resonance”? In our view, this cannot be asserted.

The term “diamagnetic resonance” emphasizes that the effect belongs to a class of magnetic resonances. In reality, however, there are no serious grounds for considering it a variety of magnetic resonance. Magnetic resonant absorption of electromagnetic energy arises as a consequence of magnetic dipole transitions induced by the magnetic component of the radiation field acting on a substance. Cyclotron resonant absorption (let us call it that for the time being) is the result of di-

* For example, the proceedings of the Amsterdam Conference on Semiconductors (autumn 1954).