Physical effects which distort measurement of the rest mass of the neutrino from beta spectra

Various physical effects which distort the result at the 1-eV accuracy level are discussed in connection with the experimental possibility of raising the sensitivity to the neutrino rest mass m _v ² to a value of the order of (1 eV)² in measurements of the beta spectra of tritium decay. There is no contradiction in an integrated spectrometer between the accuracy, the resolution, and the statistics, which there is in a differential spectrometer, and the mass sensitivity range is significantly greater. The statistical reliability of the measurements on section A of the Curie curve — Fig. 1 — is discussed, in which the problem reduces to the determination of the coefficients of the expansion (4). It is necessary in a monolayer source at an accuracy level of the order of 1–3 eV to introduce correctionfor the formation of an excited helium atom. The remaining effects are at the 1-eV level. The possibility of measuring the Curie curve in region C — near the cutoff — is demonstrated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 29–36, April, 1984.