Rotational-vibrational band structure in ¹⁵⁵Sm

The nuclear structure of ¹⁵⁵Sm has been studied via primary and secondary γ-rays and by internal conversion electrons following thermal neutron capture. Furthermore average resonance neutron capture spectra for various neutron energy ranges were recorded. A detailed level scheme with a complete set of levels with spin < 7 2 has been well established up to 1400 keV excitation energy. The neutron binding energy has been determined to be 5807.2(3) keV. The scheme is interpreted in a basis of Coriolis and ΔN = 2 coupled Nilsson states and compared with the less deformed Sm isotopes. A possible additional band coupling via the octupole vibrational mode is discussed.