Verifying the feasibility of the mobile NRTA setup with GEANT4 simulation

The Nuclear Resonance Transmission Analysis (NRTA) method has been utilized to identify unknown isotopes in materials by analyzing the attenuation of neutrons, which occurs due to the unique neutron capture resonances in each isotope. Traditionally, NRTA required large-scale neutron detection devices, long beamlines, and periodic neutron sources, such as DeuteriumTriton neutron generators and accelerators, to ensure good time-of-flight (TOF) resolution. Prior research has been conducted to overcome these limitations for in-situ usage. Recently, a mobile NRTA setup with an AmBe source was devised to surmount the limitations of using periodic neutron generators. This study aims to improve the previous NRTA setup by replacing the AmBe source with a 252Cf neutron source. To verify the feasibility of this setup, GEANT4, a MonteCarlo method-based simulation code, was used to compare the TOF spectra with an AmBe and a 252Cf source. Specifically, the study compared the number of moderated neutrons with various detector thicknesses, deposited energy distribution within the liquid scintillator detector, and TOF spectrum measurement with a tungsten (W) target. The results demonstrate that the 252Cf source could provide high statistics in the TOF spectrum and more efficient neutron moderation. Consequently, based on the GEANT4 simulation, the feasibility of replacing the AmBe source with the 252Cf source in mobile NRTA was verified.