Nitrogen concentration was measured via 2.52？MeV nitrogen gamma ray from melamine, caffeine, urea, and disperse orange bulk samples using a newly designed D-D portable neutron generator-based prompt gamma ray setup. Inspite of low flux of thermal neutrons produced by D-D reaction-based portable neutron generator and interference of 2.52？MeV gamma rays from nitrogen in bulk samples with 2.50？MeV gamma ray from bismuth in BGO detector material, an excellent agreement between the experimental and calculated yields of nitrogen gamma rays indicates satisfactory performance of the setup for detection of nitrogen in bulk samples. 1. Introduction Prompt gamma-ray neutron activation analysis (PGNAA) technique is widely used for insitu elemental analysis of bulk samples in several scientific disciplines including environmental, industrial, and health sciences [1]. Its area of application ranges from quality-control tasks in mining and environmental [2–5] and building construction industries [6] to contraband detection for homeland security in concealed containers [7–11]. Prompt gamma rays can be excited in samples via thermal neutron capture reaction and fast neutron inelastic scattering reactions. Former reaction is used for elements with appreciable thermal neutrons capture cross-sections, while later reaction is used for elements with negligible thermal neutron capture cross-section. Therefore prompt gamma rays produced via 14？MeV neutron inelastic scattering from elements are used to measure C, N, and O concentrations in bulk samples [12–16]. Due to interference of weak intensity nitrogen prompt gamma rays with oxygen gamma rays, detection of nitrogen in bulk samples is a tedious task in 14？MeV neutron inelastic scattering studies. Inspite of small thermal neutron capture cross-section, nitrogen can also be detected via prompt gamma ray studies in thermal neutron capture reaction studies [17, 18]. Conventionally, nitrogen detection in bulk sample via thermal neutron capture is carried out using a 252Cf neutron source [17, 18]. In this study nitrogen has been detected in bulk samples via thermal neutron capture using a D-D reaction-based portable neutron generator. Thermal neutrons were produced in conjunction with 2.5？MeV fast neutrons from the portable neutron generator using the high-density polyethylene moderators. The study has been carried out first time about use of a D-D portable neutron generator in detection of nitrogen in bulk samples. King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, Saudi Arabia, has acquired a portable D-D
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