Inverse beta decay of yttrium-90 under the influence of neutrino ultra-low energies

This work is devoted to the study of inverse beta decay of yttrium under the influence of neutrino ultralow energies. A. G. Parkhomov proposed for the study of cosmic neutrinos thresholdless reaction: ${}^{90}\mathrm{V}+\nu_c={}^{90}\mathrm{Zr}+e^-$ [3–5]. Since in the case of inverse beta decay, almost all the energy decay takes the electron, the maximum energy in the spectrum beta-particles will have the electrons arising due to inverse beta decay of yttrium. Therefore, such electrons easy separate on the background. Besides, the section of interaction of ultralow energy neutrinos (less than $1$ eV) with the nucleus increase by many orders of magnitude is compared with neutrinos of nuclear energy ($>100$ keV). We focused on neutrino fluxes by lead planar-concave lens. According to the results [3], the refractive index neutrinos of ultralow energies in matter less than $1$ and is about $0,8$ for lead. The flow of electrons generated in beta decay, passed through several aluminum plates, and their number was selected so that only very high-energy particles passed through plates. The electrons were registered by the GM tube connected to a computer. Beta-source — ${}^{90}\mathrm{Sr}$-${}^{90}\mathrm{Y}$ was placed in the supposed main focus of lead lens. The main optical axis of the lens was directed to the window to the east at an angle of about $30$ degrees to the horizon and its orientation did not change during the whole experiment. The duration of measurements was $2$–$3$ days. The average frequency $f_i$ and the variation coefficient $V_i$ were chosen as investigated parameters. Outliers of $f_i$ and $V_i$ were separated by using the Rosner criterion. The statistical analysis of the positive outliers of variation coefficients $V_i$ has shown a significant increase in their average value in using the focusing of neutrinos.