Measurement and GEANT4 simulation of photo-peak efficiency and covariance analysis of γ-detectors in TANGRA setup

The TANGRA project at the Frank Laboratory of Neutron Physics (FLNP), Joint Institute for Nuclear Research (JINR), Dubna, Russia, aims to investigate the inelastic scattering of 14.1[Formula: see text]MeV neutrons on atomic nuclei using the Tagged Neutron Method (TNM). As part of this research, we determined the photo-peak efficiencies of HPGe and LaBr 3 (Ce) [Formula: see text]-ray detectors at a new experimental facility. Standard point-like radioactive [Formula: see text]-ray sources ([Formula: see text]Na, [Formula: see text]Co, [Formula: see text]Ba, [Formula: see text]Cs, [Formula: see text]Eu, [Formula: see text]Th) were used for experimental calibration, and GEANT4 Monte Carlo (MC) simulations were employed to estimate full-energy peak (FEP) efficiencies. We accounted for experimental uncertainties in [Formula: see text]-ray abundance, counting statistics, radioactive source half-life and activity by generating covariance matrices to evaluate detector efficiency. The results showed agreement between MC simulations and experimental data within the limits of experimental uncertainties, demonstrating the reliability of our approach. Our findings align well with those of other studies and MCNP simulations, with improved consistency. This work provides precise efficiency measurements and covariance analysis for HPGe and LaBr 3 (Ce) detectors, offering valuable data for [Formula: see text]-ray spectroscopy applications in nuclear physics, ecology, medicine, geology and archaeology.