Scissors strength in the quasi-continuum of actinides

The M1-scissors resonance has been measured for the first time in the quasi- continuum of actinides. The strength and position of the resonances in 231,232,233 Th were determined by particle-coincidences using deuteron induced reactions on a 232 Th target. The residual nuclei show a strong integrated strength of BM1 = 9 11µ 2 in the E = 1.0 3.5 MeV region. The presence of the scissors resonance modifies significantly the (n,) cross section, which has impact on fuel-cycle simulations of fast nuclear reactors and nucleosynthesis in explosive stellar environments.