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This work investigates the Pygmy Dipole Resonance (PDR) in the deformed $^{154}\mathrm{Sm}$ nucleus. The aim is to determine whether the PDR splits with respect to the K quantum number in a deformed nucleus, as is the case for the GDR. The study uses the $(\vec{\gamma},\vec{\gamma^\prime})$ reaction to excite dipole states at energies ranging from 3.5 MeV to 7.05 MeV, approaching the neutron separation energy at 8 MeV. Measurements were taken with the Clover Array at the HI$\gamma$S facility of the Triangle Universities Nuclear Laboratory. The facility’s polarised photon beam enables measurements using the asymmetry method to distinguish between 1−and 1+ states. Given that the first excited state of $^{154}\mathrm{Sm}$ lies only 82 keV above the ground state, the high-resolution beam mode (with an achievable energy spread below 2%) allows for the determination of decay branching ratios to the first 2+ state. These branching ratios are compared with the Alaga rules to predict the geometrical decay pattern. Additionally, the results are compared with the statistical decay model to ascertain whether the PDR decays predominantly statistically or geometrically. Although a study on $^{150}\mathrm{Nd}$ reported no K-splitting [1], the current study extends this investigation to the case of $^{154}\mathrm{Sm}$.
[1] O. Papst et al., Phys. Rev. Lett., 135 (2025) 052501.