Speaker
Description
During several years at the Baksan Neutrino Observatory INR RAS is undergoing the experiment for searching of 2K (2$\nu$)-capture in $^{124}$Xe. This isotope has several advantages: 1) it has the largest kinetic energy of transition Q – 2.866 MeV, among candidates of nuclei for which predicted the existence of ECEC; 2) since xenon is the noble gas, then it could be easily use as a system isotope-detecting medium in a gas detector. To search for 2K-capture in $^{124}$Xe the large volume copper proportional counter (LPC) is used.
In our work, we present the results of the simulation, with the Geant4 package, of LPC background from the decays of $^{238}$U and $^{232}$Th nuclei in the construction materials of the LPC case, as well as in elements of the low-background shield. The influence of neutrons produced in the rock of the underground laboratory from the decay of $^{238}$U and $^{232}$Th, where the experimental setup is located, on the production of the $^{125}$I isotope in the working gas of the detector, upon capture of thermalized neutrons by the $^{124}$Xe isotope is considered. The $^{125}$I isotope can have a significant influence on the background of the experiment since the total energy release in its decay belongs to the same energy region as ROI of 2K-capture in $^{124}$Xe.
