Why Auger Decay Should Remain “Auger Decay”

Auger effect. Left: Molecular-orbital diagram illustrating two-electron transition filling the core vacancy and ejecting an electron. Center: Auger spectrum of benzene showing discrete peaks. Right: Molecular-orbital picture of the main decay channels in benzene. Figures are from the author’s research.

In 2019, Physics Today published a page-and-half essay titled “A Renaming Proposal: ‘The Auger–Meitner Effect.’” The authors (who include a science historian) claimed that Lise Meitner, a famous Austrian-born nuclear physicist, was the first to describe the nature of secondary electrons in the nuclear decay process, which—as we now understand—have a similar nature to the secondary electrons emitted following an X-ray excitation of atoms or molecules. The essay referred to a 1988 essay by Richard Sietmann, provocatively titled “False Attribution,” and cited two papers by Meitner published in Z. Phys. in 1922 and 1923 as well as a seminal paper by Pierre Auger published in 1923. On its face, the argument looked convincing, and many scientists—including me—began to use the term “Auger-Meitner decay” to give Meitner her much-belated due. Even Meitner’s Wikipedia article claims that “Meitner has discovered the cause of the emission of electrons from surfaces of atoms with ‘signature’ energies.”

But, as I later realized, adopting this renaming proposal had been a poorly informed move. I am sure the authors of the Physics Today essay had the best intentions; however, they misinterpreted the history of Auger decay. A detailed analysis of this history is given by Olivier Duparc. In a nutshell:

Meitner’s concern was the exact nature of the (nuclear) beta radiations about which she opposed Ch. D. Ellis, and this had been the subject of an intense Berlin–Cambridge controversy where Ellis’ description eventually prevailed. Auger’s observations were the central theme of his PhD thesis at the J. Perrin’s laboratory on the composed photoelectric effect.

In simple terms, Meitner was primarily focused on the origin of primary beta-rays in nuclear decay—and she was fundamentally wrong in her interpretation of their nature. The secondary or tertiary—depending how you count—electrons responsible for discrete spectral lines and emitted from the atomic shell rather than the nucleus were discussed not only by Meitner, but also by Charles Ellis who offered a similarly hand-waving explanation of their nature already in 1921.

In contrast, Auger had carried out original experiments using the cloud chamber technique and provided the correct explanation of the “secondary photoelectric effect,” which, except for the invocation of virtual photons, stands today:

When the first [atomic] electron leaves [the atom, ejected by an incident X-ray], as a secondary b-ray, there is a vacancy left in the electronic system of the excited atom. The drop of a more peripheral electron on that level is accompanied by the emission of a characteristic radiation quantum. This quantum may be absorbed in the atom itself, and produce, at the expense of the peripheral levels [the outer electronic shells], a tertiary beta-ray (. . .). The repetition of that process must lead to the production of a fourth order ray; and I indeed believe I have observed such rays in the case of [gaseous] iodine.

Pierre Victor Auger. Image via Int. J. Mat. Res.

I highly recommend Duparc’s essay to anyone who has an interest in the history of scientific discoveries. This essay was actually cited in the Physics Today piece, but Duparc’s scientifically well-argued conclusions were completely ignored by the authors.

Lise Meitner in 1906. Image source: Wikimedia Commons

Meitner was a titan of theoretical physics and a trailblazer for women in science. Her life story is both sad and inspiring. She started her career in the basement of Emil Fisher’s institute in Berlin and was not even allowed to go into the building’s seminar rooms or research labs. To access a bathroom, she had to go to a hotel across the street. But owing to her brilliance and hard work, she worked her way up from the basement to the department’s head office. That was a success story. Unfortunately, her career advancement coincided with the rise of Nazism, and soon “the Jewess” was chased out of the institute (in 1935) and the country (in 1938).

Lise Meitner and Otto Hahn in 1912. Image source: Wikimedia Commons

Meitner was also unfairly treated by the Nobel Committee, who failed to recognize her key contribution to nuclear fission, awarding the sole prize to Otto Hahn, an injustice that several contemporaries of Meitner—including Albert Einstein—unsuccessfully tried to redress by repeatedly renominating her to the Nobel Prize (more than 30 times!). Meitner made several seminal contributions for which she may not have received adequate recognition, but Auger decay was not one of them. Indeed, she never claimed this discovery herself, and in her own writings, she referred to it as the “Rosseland–Augereffekt.”

We should cherish Meitner’s memory and celebrate her brilliant work, but it is utterly inappropriate—and I would even argue, insulting to her memory—to attach her name to this discovery, one to which she did not meaningfully contribute. Meitner was a great scientist; she does not need false credits. Let us respect history and leave Auger decay to Auger.

References:

Demetrios Matsakis, Anthea Coster, Brenda Laster, Ruth Sime, A renaming proposal: “The Auger–Meitner effect”; Physics Today 72 10–11 (2019)

Olivier Hardouin Duparc, Pierre Auger – Lise Meitner: Comparative contributions to the Auger effect; Int. J. Mat. Res. 100 1162-1166 (2009)

Richard Sietmann, False Attribution; Phys. Bull. 39 316-317 (1988)

Lise Meitner, Looking Back; Bulletin of the Atomic Scientists 20 2-7 (1964)

O. R. Frisch, Lise Meitner (1878-1968); Biographical Memoirs of Fellows of the Royal Society 16 405-420 (1970)