Level densities and radiative strength functions in 171Yb and 170Yb nuclei have been measured using the 171Yb(3He,3He′γ)171Yb and 171Yb(3He,αγ)170Yb reactions. New data on 171Yb are compared to a previous measurement for 171Yb from the 172Yb(3He,αγ)171Yb reaction. Systematics of level densities and radiative strength functions in 170,171,172Yb are established. The entropy excess in 171Yb relative to the even-even nuclei 170,172Yb due to the unpaired neutron quasiparticle is found to be approximately 2kB. Results for the radiative strength function from the two reactions lead to consistent parameters characterizing the ``pygmy'' resonances. Pygmy resonances in the 170,172Yb populated by the (3He,α) reaction appear to be split into two components for both of which a complete set of resonance parameters are obtained.
@article{arxiv.nucl-ex/0412029,
title = {Level densities and $\gamma$-ray strength functions in $^{170,171,172}$Yb},
author = {U. Agvaanluvsan and A. Schiller and J. A. Becker and L. A. Bernstein and P. E. Garrett and M. Guttormsen and G. E. Mitchell and J. Rekstad and S. Siem and A. Voinov and W. Younes},
journal= {arXiv preprint arXiv:nucl-ex/0412029},
year = {2009}
}