5 MV underground accelerator in the Dresden Felsenkeller

Nuclear reaction studies by in-beam gamma-spectroscopy with a low expected signal counting rate are best performed in a low-background environment. At gamma-ray energies above 3 MeV that are typical of many nuclear reactions, the background is given by cosmic-ray effects. Thick layers of rock absorb cosmic-ray muons and thus attenuate these effects.

At the Felsenkeller underground site in Dresden, shielded by 47 m of rock, the cosmic-ray muon flux is reduced by a factor of 30. It has recently been shown that additional active shielding brings the total background suppression factor to several hundred, creating an attractive environment for nuclear reaction studies for astrophysics and applications.

A 5 MV Pelletron tandem accelerator with double charging chains was recently purchased for installation in Felsenkeller and has already been transported to Dresden. Recent progress of the project will be reviewed, and an outlook will be given.