1：Experimental Design and Method Selection:

The study involved testing the nGEM detector's directionality using 2.5 MeV neutrons from the FNG facility. The detector was tilted at various angles to assess its response to neutron incidence angles, with simulations (e.g., MCNP) used to predict behavior.

2：5 MeV neutrons from the FNG facility. The detector was tilted at various angles to assess its response to neutron incidence angles, with simulations (e.g., MCNP) used to predict behavior. Sample Selection and Data Sources:

2. Sample Selection and Data Sources: The nGEM detector was the primary sample, tested with neutrons generated by impinging a deuterium beam on a deuterium target at FNG, producing quasi-monochromatic 2.5 MeV neutrons.

3：5 MeV neutrons. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: nGEM detector, FNG neutron generator, NE213 scintillator for neutron flux monitoring, angular positioner, analogue electronic chain (ORTEC preamplifier, spectroscopy amplifier, ADC-Multi Channel Analyzer), digital acquisition system (CARIOCA-GEM chips, FPGA Mother Board), high voltage system (HVGEM NIM module), gas mixture (Ar/CO2 70%-30%).

4：Experimental Procedures and Operational Workflow:

The detector was mounted on an angular positioner at FNG, tilted from 0° to 80° in steps of 10°. Pulse height spectra were acquired using analogue electronics for energy deposition analysis, and digital setup was used for spatial profile mapping. Neutron flux was monitored continuously.

5：0°. Pulse height spectra were acquired using analogue electronics for energy deposition analysis, and digital setup was used for spatial profile mapping. Neutron flux was monitored continuously. Data Analysis Methods:

5. Data Analysis Methods: Pulse height spectra were integrated from 150 keV to discriminate gamma background. Data were normalized and compared to simulations (MCNP) to verify directionality. Spatial profiles were analyzed to confirm angular response.