Gamma Background Measurements at BEO Moussala

Recent measurements of radiation gamma background at high mountain altitude, namely at Basic Environmental Observatory Moussala (42{\deg}10' 45" N; 23{\deg} 35'07"E, 2925m a.s.l.) are carried out. The measurements are fulfilled with several different devices, namely IGS-421 gamma probe and MDU Liulin spectrometer. The used instrumentation with their characteristics is described. The obtained results are compared with previously obtained measurements carried out with NaI SAPHYMO gamma probe. In addition the measurements are compared with TLD data. The obtained results from measurements are widely discussed. The contribution of galactic cosmic rays to dose rate is estimated on the basis of a numerical model. The model is based on a full Monte Carlo simulation of cosmic ray induced nuclear-electromagnetic-muon cascade in the atmosphere. The simulation is carried out with CORSIKA 6.52 code using FLUKA 2006 and QGSJET II hadron interaction models. The application of the model is briefly discussed.