NAUTILUS · Neutron cAptUres consTraIning steLlar nUcleosynthesiS

NAUTILUS will investigate the nucleosynthesis of the chemical elements during the evolution of stars, which is the basis for understanding the chemical history of the Universe. The vast majority of the elements heavier than iron are produced by neutron capture reactions. The precise knowledge of the involved neutron capture cross sections for certain isotopes sets tight limits for stellar parameters and puts strong constraints on the age of the Universe.Accurate measurements of the key nuclear reactions in the mass region around the radioactive 85Kr will lead to the improvements needed to characterize the production processes of the elements in stars. The respective high-accuracy abundance patterns in single stars can then be interpreted as diagnostic tools for the deep stellar interior and the isobaric 87Sr/87Rb chronometer constraints the history of the Universe.The neutron capture cross section of radioactive isotopes for neutron energies in the keV region will be measured by a time-of-flight (TOF) experiment. NAUTILUS will provide a unique facility realizing the TOF technique with an ultra-short flight path at the FRANZ setup at Goethe University Frankfurt am Main, Germany. A highly optimized spherical photon calorimeter will be built and installed at an ultra-short flight path.NAUTILUS opens new horizons in the area of neutron-induced reaction research, as smallest samples like of 85Kr - which will be produced as an isotopically pure radioactive sample - will become measureable in reasonable times.Future applications include the study of neutron capture cross sections important for next generation nuclear reactors: For the first time the high neutron fluxes needed to study the mass region of interest in the keV energy range will be available.""