Photoexcitation of low-lying dipole transitions inU236

Nuclear resonance fluorescence experiments have been performed on the deformed actinide nucleus ${}_{}{}^{236}{}_{}{}^{}\mathrm{U}$. Bremsstrahlung of 3.9 MeV endpoint energy has been used as the photon source. The scattered photons were detected by three high resolution Ge-γ-spectrometers installed at scattering angles of 92°, 128°, and 150°, respectively. Precise excitation energies, decay branching ratios, and ground state decay widths of numerous previously unknown spin 1 states in the excitation energy range 1.8–3.2 MeV have been extracted. The dipole strength has been found to be concentrated in the energy range 2.1–2.5 MeV. The systematics of the so-called scissors mode observed as a result of the previous (γ,γ’) and (e,e’) experiments on ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$ and ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ and, in particular, their combined analysis suggests likewise to attribute these new dipole excitations in ${}_{}{}^{236}{}_{}{}^{}\mathrm{U}$ to the orbital M1 scissors mode.