Astrophysical Aspects of Neutron Physics

Modern ideas of the evolution of the early universe are presented, and then the scenarios of the formation and evolution of stars and the processes governing nuclear reactions occurring in stars, including nucleosynthesis, are described. Particular attention is given to the production of elements that are heavier than iron by a successive capture of neutrons (s and r processes); to calculate these reactions, detailed data are required on the cross sections for (pi,gamma) reactions averaged over the Maxwellian spectra of neutrons at temperatures on the order of 10-100 keV. The most important reactions are those with small cross sections and/or with excited and unstable nuclei. The existing experimental setups and those being developed at the Institute for Nuclear Research (Russian Academy of Sciences) and the Laboratory of Neutron Physics of JINR for measuring these reactions are described.