Search for the Neutrino Magnetic Moment in the Non-Equilibrium Reactor Antineutrino Energy Spectrum

We study the time evolution of the typical nuclear reactor antineutrino energy spectrum during reactor ON period and the decay of the residual antineutrino spectrum after reactor is stopped. We find that relevant variations of the soft recoil electron spectra produced via weak and magnetic ${\widetilde {\nu}}_{e},e$ scattering process can play a signigicant role in the current and planned searches for the neutrino magnetic moment at reactors.Comment: 4 pages LaTeX 2.09. 4 PS figures. Resume of seminar talks given at Kurchatov Institute, March 1999

Reactor as a Source of Antineutrinos: Thermal Fission Energy

Deeper insight into the features of a reactor as a source of antineutrinos is required for making further advances in studying the fundamental properties of the neutrino. The relationship between the thermal power of a reactor and the rate of the chain fission reaction in its core is analyzed.Comment: 15 pages in LaTex and 4 ps figure

Inverse Beta Decay in a Nonequilibrium Antineutrino Flux from a Nuclear Reactor

The evolution of the reactor antineutrino spectrum toward equilibrium above the inverse beta-decay threshold during the reactor operating period and the decay of residual antineutrino radiation after reactor shutdown are considered. It is found that, under certain conditions, these processes can play a significant role in experiments seeking neutrino oscillations.Comment: 8 pages including 5 ps figure

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

Neutrino Geophysics at Baksan I: Possible Detection of Georeactor Antineutrinos

J.M. Herndon in 90-s proposed a natural nuclear fission georeactor at the center of the Earth with a power output of 3-10 TW as an energy source to sustain the Earth magnetic field. R.S. Raghavan in 2002 y. pointed out that under certain condition antineutrinos generated in georeactor can be detected using massive scintillation detectors. We consider the underground Baksan Neutrino Observatory (4800 m.w.e.) as a possible site for developments in Geoneutrino physics. Here the intrinsic background level of less than one event/year in a liquid scintillation ~1000 target ton detector can be achieved and the main source of background is the antineutrino flux from power reactors. We find that this flux is ~10 times lower than at KamLAND detector site and two times lower than at Gran Sasso laboratory and thus at Baksan the georeactor hypothesis can be conclusively tested. We also discuss possible search for composition of georector burning nuclear fuel by analysis of the antineutrino energy spectrum.Comment: 7 pages in LaTeX, 3 PS figures, Submitted to Physics of Atomic Nucle

Inverse beta decay reaction in 232^{232}Th and 233^{233}U fission antineutrino flux

Energy spectra of antineutrinos coming from $^{232}$Th and $^{233}$U neutron-induced fission are calculated, relevant inverse beta decay $\bar{{\nu}_e}+p \to n + e^{+}$ positron spectra and total cross sections are found. This study is stimulated by a hypothesis that a self-sustained nuclear chain reaction is burning at the center of the Earth ("Georeactor"). The Georeactor, according to the author of this idea, provides energy necessary to sustain the Earth's magnetic field. The Georeactor's nuclear fuel is $^{235}$U and, probably, $^{232}$Th and $^{233}$U. Results of present study may appear to be useful in future experiments aimed to test the Georector hypothesis and to estimate its fuel components as a part of developments in geophysics and astrophysics based on observations of low energy antineutrinos in Nature.Comment: 6 pages in LaTeX and 2 ps figures. Submitted to Physics of Atomic Nucle

Linking the evolution of catalytic properties and structural changes in copper-zinc nanocatalysts using operando EXAFS and neural-networks

Understanding the evolution of unique structural motifs in bimetallic catalysts under reaction conditions, and linking them to the observed catalytic properties is necessary for the rational design of the next generation of catalytic materials. Extended X-ray absorption fine structure (EXAFS) spectroscopy is a premier experimental method to address this issue, providing the possibility to track the changes in the structure of working catalysts. Unfortunately, the intrinsic heterogeneity and enhanced disorder characteristic of catalytic materials experiencing structural transformations under reaction conditions, as well as the low signal-to-noise ratio that is common for in situ EXAFS spectra hinder the application of conventional data analysis approaches. Here we address this problem by employing machine learning methods (artificial neural networks) to establish the relationship between EXAFS features and structural motifs in metals as well as oxide materials. We apply this approach to time-dependent EXAFS spectra acquired from copper–zinc nanoparticles during the electrochemical reduction of CO2 to reveal the details of the composition-dependent structural evolution and brass alloy formation, and their correlation with the catalytic selectivity of these materials