Development and Validation of a Low-Cost Portable Gamma Radiation Spectrometer for Environmental Monitoring in the Niger Delta

Background: Environmental radioactivity monitoring in Nigeria's Niger Delta is hindered by the high cost of commercial gamma spectrometers. A low-cost, portable alternative capable of nuclide-specific quantification would significantly advance environmental health surveillance. Aim: This study developed and validated a low-cost portable gamma radiation spectrometer for field deployment in Niger Delta environmental monitoring. Methods: The spectrometer was constructed using a 2x2 inch NaI(Tl) scintillator crystal, a silicon photomultiplier, and a multichannel analyser implemented on a Raspberry Pi 4 with custom Python-based spectral analysis software. Energy calibration was performed using Cs-137, Co-60, and Am-241 reference sources. Field validation was conducted against a calibrated HPGe reference system at 15 Niger Delta sampling sites. Results: Energy resolution was 7.8% at 662 keV (Cs-137). Activity concentration measurements agreed with HPGe reference values within 12% for major environmental radionuclides. The instrument detected elevated U-238 progeny activity at four oil-impacted sites. Total component cost was NGN 185,000, compared with NGN 8 to 15 million for commercial equivalents. Conclusion: The developed portable spectrometer provides adequate environmental monitoring capability at a fraction of commercial instrument costs. It is suitable for systematic Niger Delta radioactivity baseline mapping. Keywords: gamma spectrometer, environmental radioactivity, Niger Delta, NaI detector, low-cost instrumentation.