The indication for 40^{40}K geo-antineutrino flux with Borexino phase-III data

We provide the indication of high flux of $^{40}$K geo-antineutrino and geo-neutrino ($^{40}$K-geo-($\bar{\nu} + \nu$)) with Borexino Phase III data. This result was obtained by introducing a new source of single events, namely $^{40}$K-geo-($\bar{\nu} + \nu$) scattering on electrons, in multivariate fit analysis of Borexino Phase III data. Simultaneously we obtained the count rates of events from $^7$Be, $pep$ and CNO solar neutrinos. These count rates are consistent with the prediction of the Low metallicity Sun model SSM B16-AGSS09. MC pseudo-experiments showed that the case of High metallicity Sun and absence of $^{40}$K-geo-($\bar{\nu} + \nu$) can not imitate the result of multivariate fit analysis of Borexino Phase III data with introducing $^{40}$K-geo-($\bar{\nu} + \nu$) events. We also provide arguments for the high abundance of potassium in the Earth.Comment: 17 pages, 7 figures. arXiv admin note: substantial text overlap with arXiv:2202.08531 We have corrected and expanded the section on radiogenic heat of the Earth. Improved the quality of drawings. The results of the study are partially described in L. B. Bezrukov, I. S. Karpikov, A. K. Mezhokh, S. V. Silaeva and V. V. Sinev, Bulletin of the Russian Federation. 87 (7), 972 (2023

The system of EAS time analysis

The extensive air showers' (EAS) front shape, angle of incidence, disk thickness, particle distribution along the shower, on the delayed and EAS front advancing particles were determined. The suggested system of the EAS time analysis allows determination of the whole EAS longitudinal structure at the observation points. The information from the detectors is continuously recorded in the memory with the memory cell switching in 5 ns, this enables fixation of the moment of pulse input from the detector with an accuracy to + or - 2.5 ns. Along with the fast memory, a slow memory with the cell switching in 1 micron s is introduced in the system, this permits observation of relatively large time intervals with respect to the trigger pulse with an appropriately lower accuracy

Inelastic Scattering of Tritium-Source Antineutrinos on Electrons of Germanium Atoms

Processes of the inelastic magnetic and weak scattering of tritium-beta-source antineutrinos on the bound electrons of a germanium atom are considered. The results obtained by calculating the spectra and cross sections are presented for the energy-transfer range between 1 eV and 18 keV.Comment: Latex, 7 pages, 8 ps figure

Weak and Magnetic Inelastic Scattering of Antineutrinos on Atomic Electrons

Neutrino scattering on electrons is considered as a tool for laboratory searches of the neutrino magnetic moment. We study inelastic $\bar\nu_ee^-$-scattering on electrons bound in the germanium (Z=32) and iodine (Z=53) atoms for antineutrinos generated in a nuclear reactor core and also in the $^{90}$Sr-$^{90}$Y and $^{147}$Pm artificial sources. Using the relativistic Hartree-Fock-Dirac model, we calculate both the magnetic and weak scattering cross sections for the recoil electron energy range of 1 to 100 keV where a higher sensitivity to the neutrino magnetic moment could be achieved. Particular attention is paid to the approximate procedure which allows us to take into account the effects of atomic binding on the inelastic scattering spectra in a simple way.Comment: 7 pages in LaTeX, 10 figures in P

The Kr2Det project: Search for mass-3 state contribution |U_{e3}|^2 to the electron neutrino using a one reactor - two detector oscillation experiment at Krasnoyarsk underground site

The main physical goal of the project is to search with reactor antineutrinos for small mixing angle oscillations in the atmospheric mass parameter region around {\Delta}m^{2}_{atm} ~ 2.5 10^{-3} eV^2 in order to find the element U_{e3} of the neutrino mixing matrix or to set a new more stringent constraint (U_{e3} is the contribution of mass-3 state to the electron neutrino flavor state). To achieve this we propose a "one reactor - two detector" experiment: two identical antineutrino spectrometers with $\sim$50 ton liquid scintillator targets located at ~100 m and ~1000 m from the Krasnoyarsk underground reactor (~600 mwe). In no-oscillation case ratio of measured positron spectra of the \bar{{\nu}_e} + p \to e^{+} + n reaction is energy independent. Deviation from a constant value of this ratio is the oscillation signature. In this scheme results do not depend on the exact knowledge of the reactor power, nu_e spectra, burn up effects, target volumes and, which is important, the backgrounds can periodically be measured during reactor OFF periods. In this letter we present the Krasnoyarsk reactor site, give a schematic description of the detectors, calculate the neutrino detection rates and estimate the backgrounds. We also outline the detector monitoring and calibration procedures, which are of a key importance. We hope that systematic uncertainties will not accede 0.5% and the sensitivity U^{2}_{e3} ~4 10^{-3} (at {\Delta}m^{2} = 2.5 10^{-3} eV^2) can be achieved.Comment: Latex 2e, 9 pages and 5 ps figure