Nuclear level density plays an important role in estimation of nuclear reaction rates, statistical calculations of astrophysics, spallations neutrons measurements, and studies of intermediate-energy heavy-ion collisions. In particular, level densities have been used successfully in calculation of the neutron-capture cross-section basic data required for both design and nuclear model calculations in nuclear science and technologies.

In this study the nuclear level density based on nuclear low-lying collective level bands at excitations near neutron binding energy is analyzed in terms of collective excitation modes. The nuclear level-density parameters of some large deformed odd-A and odd-odd nuclei in the region of rare earth elements have been calculated by considering different excitation bands of observed nuclear spectra. The method used assumes equidistant spacing of the collective coupled state bands of nuclei considered. The values of calculated nuclear level-density parameters have been compared with those of the compiled values for s-wave neutron resonance data.