Decaying cosmic ray nuclei in the local interstellar medium

Secondary radioactive isotopes that are used for the determination of cosmic ray age, have relatively short decay lifetimes. The measured abundance of these isotopes at low energies is representative of the cosmic ray diffusion and the gas distribution in a region of a few hundred parsecs around the Sun. We show how to determine the local cosmic ray diffusion coefficient in the Galaxy using the data on decaying cosmic ray nuclei.