The origin of elements, particularly those heavier than nickel, remains an active research area, with explosive nucleosynthesis playing a crucial role. Understanding this process requires a reliable equation of state for nuclear matter, especially for asymmetric matter, where the symmetry energy is less understood. Recent studies indicate that constraints on symmetry energy can be derived from the neutron skin thickness of nuclei, which is linked to dipole polarizability. This can be measured through the complete dipole response. The current work details the setup and commissioning of the NEPTUN low energy photon tagger at the S-DALINAC electron accelerator, which produces tagged bremsstrahlung photons between 1 MeV and 20 MeV. This photon beam, with about 25 keV energy resolution, is utilized to investigate the dipole response of nuclei. The LaBr:Ce-based gamma-spectrometer GALATEA efficiently detects both direct and cascading decays without needing a calibration target for photon flux. Initial studies focused on the 8215.4 keV resonance of ³²S, confirming integrated cross sections consistent with literature and detecting cascade decays. NEPTUN aims to measure the complete dipole response of stable Sn isotopes, with preliminary measurements on a ¹¹²Sn target showing promising results. A significant upgrade is underway to enhance measurement speed, with new designs and prospective measurements outlined.
