  The background spectrum of a germanium detector, shielded from the radiations
arriving from the lower and open for the radiations arriving from the upper
hemisphere is studied, both in a ground level and in an underground laboratory.
It is established that the continuous portion of this background spectrum is
mostly due to the radiations that arrive from the upper hemisphere of the
continuous spectrum similar to the instrumental one. The intensity of this
radiation of an average energy of about 120 keV is estimated to about 8000
photons/m2s 2\pi srad in a ground level laboratory, and to about 5000
photons/m2s 2\pi srad at the depth of 25 m.w.e. Rough estimates of the dose
that it contributes to the skin are about 1.5 nSv/h and 1 nSv/h respectively.
Simulations by GEANT4 and CORSIKA demonstrate that this radiation is both of
cosmic and terrestrial origin, mixed in proportion that still has to be
determined.
