NUCLEAR METHODS IN RARE EVENT AND COSMIC-RAY RESEARCH

Two aspects of searches for rare processes will be included in this project – first, we shall study some of the rare nuclear processes themselves that are within the reach of our means, like the two-positron decay, some resonant and non-resonant nuclear excitations, and deexcitations of nuclear isomer states, and secondly, we plan to study in greatest detail the background processes induced in our detectors and their environment, both by cosmic rays and by radiations originating from natural radioactivity. This last activity is relevant to the understanding of background in the searches of rare processes of maximum sensitivity performed in deep underground laboratories, which should benefit from our working in the surface and shallow underground laboratories.The project is a continuation of our long-term efforts in the development of detector systems and nuclear methods for the study of rare phenomena and processes induced by cosmic rays.Further methodological developments of experimental techniques of low-background gamma-ray spectroscopy will result in lowering of detection limits of germanium detector systems. These advanced experimental techniques will improve the sensitivity of measurements of radioactive purity of materials which are to be used in searches for rare processes of ultimate sensitivity worldwide. The cross sections for the processes induced by cosmic rays in different materials will be determined.