  High-purity germanium (HPGe) detectors used for low-background gamma ray
spectrometry are usually operated under either a fairly low overburden of the
order of one meter of water equivalent (mw.e.) or a high overburden of the
order of 100mw.e. or more, e.g. in specialized underground laboratories. The
Dortmund Low Background Facility (DLB) combines the advantages of both
approaches. The artificial overburden of 10mw.e. already shields the hadronic
component of cosmic rays. The inner shielding, featuring a state-of-the-art
neutron shielding and an active muon veto, enables low-background gamma ray
spectrometry at an easy-accessible location at the campus of the Technische
Universit\"at Dortmund.
  The integral background count rate between 40keV and 2700keV is
2.528+-0.004counts/kg/minute. This enables activity measurements of primordial
radionuclides in the range of some 10mBq/kg within a week of measurement time.
