The photon tagger NEPTUN at S-DALINAC. Current status and research program

The low energy photon tagger NEPTUN at the S-DALINAC delivers a quasi-monoenergetic photon beam between about 1MeV and 20MeV with a resolution of approximately 25keV. Tagged photons provide the possibility to measure the full dipole strength of nuclei in the energy range below and above the neutron threshold. The highly efficient LaBr₃:Ce based spectrometer GALATEA will be used to detect not only the direct decays to the ground state, but also cascading decays can be measured with suitable efficiency. To measure (γ, n)- and (γ, nγ)-reactions the setup will be extended by neutron detectors based on liquid scintillators. The data will be combined with experiments at Duke University, GSI and RIKEN to obtain a complete picture of dipole strength function evolution in Sn isotopes. This talk covers the link between the different experiments and focus on the setup and status of the NEPTUN commissioning program. If available, data from the first runs with Sn will be shown.