Abstract
Spectra of gamma rays following the neutron capture at isolated resonances of stable Gd nuclei were measured. The objectives were to get new information on photon strength of Gd-153,Gd-155-159 with emphasis on the role of the M1 scissors-mode vibration.
An analysis of the data obtained clearly indicates that the scissors mode is coupled not only to the ground state, but also to all excited levels of the nuclei studied. The specificity of our approach ensures unbiasedness in estimating the sumed scissors-mode strength Sigma B(M1)up arrow, even for odd product nuclei, for which conventional nuclear resonance fluorescence measurements yield only limited information.
Our analysis indicates that for these nuclei the sum Sigma B(M1)up arrow increases with A and for Gd-157,Gd-159 it is significantly higher compared to Gd-156,Gd-158.