Александр Нозик

Relativistic runaway electron avalanches (RREAs) are generally accepted as a source of thunderstorms gamma ray radiation. Avalanches can multiply in the electric field via the relativistic feedback mechanism based on processes with gamma rays and positrons. This study shows that a non-uniform electric field geometry can lead to the new RREAs multiplication mechanism—“reactor feedback,” due to the exchange of high-energy particles between different accelerating regions within a thundercloud. A new method for the numerical simulation of RREA dynamics within heterogeneous electric field structures is proposed. Under the assumption that reactor feedback can produce a terrestrial gamma ray flash (TGF), necessary conditions for TGF occurrence in the system with the reactor feedback are derived using the developed analytical description and the numerical simulation. Observable properties of TGFs influenced by the proposed mechanism are discussed.

Information systems of experiments make a significant contribution to solving automation tasks of data collecting, storing, processing and analysis, and are used to support a lot of types of experiment activities. The article is devoted to one of information systems being actively employed in particle collision experiments—Event Metadata System, which provides a database containing information on summary properties of physics events and references to their storage location, and ensures fast search through stored event metadata. The Event Metadata System for the NICA experiments is based on the Event Catalogue and provides recording and managing information being necessary for a convenient search for events required in physics analyses. 

This paper is dedicated to the simulation of the so-called trapping-effect observed in the Troitsk nu-mass experiment. The effect is caused by the magnetic trapping of decay electrons in the windowless gaseous tritium source and the gradual evaporation of those electrons. As a result, alongside regular tritium beta-spectrum electrons, we see additional electrons that are initially trapped in the source and escape it with changed energy. The spectrum of evaporated electrons is quite peculiar (almost flat for monochromatic initial electrons) and could not be directly measured in the experiment. So one has to rely on simulations. Also, it is possible that the same effect could be observed in other cases of magnetic traps. © 2021 IOP Publishing Ltd and Sissa Medialab.