  The gamma-ray background in the indoor environment has been measured up to 3
MeV to evaluate the feasibility of studying low cross-section (nanobarn to
picobarn range) astrophysical reactions at the Facility for Research in
Experimental Nuclear Astrophysics (FRENA), Saha Institute of Nuclear Physics,
Kolkata. An n-type coaxial HPGe detector with 20% relative efficiency has been
placed at different locations in the accelerator and beam halls for the
measurement. The measured activity has been compared with that at two
laboratories (with standard brick walls) with and without passive and active
radiation shielding. As the halls at FRENA are well shielded by concrete, the
contribution of the shielding in indoor gamma-ray background has been
delineated by simulation using a 4p-geometry model.
