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Technology, electrical characteristics and detection performance of a novel recently developed and fabricated 64-pixel two-line array chip for detection of X- and γ -rays based on semi-insulating GaAs from three different producers are reported and compared. The chip has dimensions of cca (16 × 4 × 0.25) mm3. A single pixel has an active area of (300 × 190) μm2 with a pitch of 250 μm. The distance between two lines is 360 μm. The reverse current density (at 295 K) of a single pixel at a bias voltage of 200 V ranges from 90 to 140 nA/mm2. The breakdown voltage ranges between 250 and 500 V. Pulse-height spectra of radionuclide 241Am in the top irradiation mode are demonstrated. The best spectrometric performance is achieved with the Freiberger material. The charge collection efficiency of about 85% and energy resolution in the full width at half maximum better than 8.6 keV for the 59.5 keV photopeak was reached at 295 K and bias of 300 V.