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Bulk semi-insulating (SI) GaAs material due to its relatively high resistance against neutrons [1,2] seems to be an excellent candidate for fabrication of a neutron detector (e.g. neutron digital imaging). Influence of various neutron integral fluencies was studied at a set of detectors based on semi-insulating GaAs. Changes in the detection and electrical properties occurred at various neutron fluencies. Performance of the detectors before and after neutron irradiation was observed via detected spectra of Am radionuclide source. At lower fluencies of neutrons (~1012 n/cm2) the changes in detected spectra and also in current-voltage characteristics are negligible while in the detectors bombarded with higher neutron fluencies (~1013 n/cm2) a fast degradation of detection performance occurred. With increasing fluencies, a rise in the reverse current of the detectors was observed. These observations are the most probably caused by new lattice defects in the base material or overall detector structure (electrode interfaces, surface) created by neutrons.