Letters to the Editor

On the Article by S. Larin “Anomalous Scattering of β-Rays and the Hypothesis of ‘Sticking Together’ of Elementary Particles”*)

In the article mentioned, S. Larin draws the conclusion that charged particles exist with a mass several times greater than the electron mass—so-called “electrinos,” which are β-radiation.

Such particles would have to be produced in abundance in the absorption of hard gamma quanta by materials with a large atomic number, analogously to the formation of electron–positron pairs.**)

At present, in various countries there are a large number of machines giving γ-quanta with energies sufficient for the formation of such particles with masses of 3–10–20 electron masses. Undoubtedly, a large number of cases of electron–positron-pair formation have been observed, but there are no indications whatever of the formation of electrinos under these conditions.

The spectra of β-decays of mirror nuclei agree excellently with Fermi’s theory both for β-decay energies insufficient for the formation of an electrino and for β-decay energies exceeding the presumed rest mass of the electrino; this fact also indirectly testifies against the electrino hypothesis.

It is known (Phys. Rev. 73, 1472 (1948)) that if some other charged particles were formed in β-decay, then these particles, in dense matter, could fall into the \(K\)-orbit, emitting X-ray quanta with energy proportional to the mass of the particle. Ordinary electrons do not produce such radiation, since the \(K\)-orbit is occupied by electrons and the Pauli principle applies to them. For μ-mesons, X-rays of such origin have recently been studied in detail. The authors of the article cited above studied the decay of \(C^{14}\) (decay energy of about 150 keV), where electrino formation cannot be expected. However, in numerous other studies of gamma rays accompanying β-processes, such X-radiation likewise was not observed.

Summarizing the specific considerations given above, one may state with certainty that an electrino with mass \(3–10\,m_e\) and lifetime \(\sim 10^{-10}\) sec does not exist in nature.

With the modern experimental technique and the scale of work, and with the enormous interest in elementary particles, it is impossible to think that a particle with the properties of the electrino, easily produced and conveniently detectable, has remained unstudied up to now.

*) See Uspekhi Fizicheskikh Nauk 52, issue 2 (1954).
**) I. E. Tamm noted that in this process all charged particles existing in nature with mass less than \(h\omega/2c^2\) should be produced.