Neutron capture cross sections of unstable isotopes are important for neutron induced nucleosynthesis as well as for technological applications. The Rare Isotope Accelerator (RIA) or comparable facilities will be able to produce radioactive ion beams up to 10 12 particles/s and would therefore be a suitable place for (n,γ) studies on radioactive isotopes with half-lives between days and months. We propose a facility for measurements of (n,γ) cross sections of unstable isotopes in the keV range suited for minimal sample masses down to 10 15 atoms, corresponding to minimum half-lives of only 10 d.