UPBEND AND M1 SCISSORS MODE IN NEUTRON-RICH NUCLEI -CONSEQUENCES FOR r-PROCESS (n, γ) REACTION RATES

An enhanced probability for low-energy gamma-emission (upbend, E-gamma < 3 MeV) at high excitation energies has been observed for several light and medium-mass nuclei close to the valley of stability. Also the M1 scissors mode seen in deformed nuclei increases the gamma-decay probability for low-energy gamma-rays (E-gamma approximate to 2 -3 MeV). These phenomena, if present in neutron-rich nuclei, have the potential to increase radiative neutron-capture rates relevant for the r-process. The experimental and theoretical status of the upbend is discussed, and preliminary calculations of (n, gamma) reaction rates for neutron-rich, mid-mass nuclei including the scissors mode are shown.