Simulated design of neutron ambient dose equivalent meter with gadolinium core plastic scintillator using Geant4 code

It has been demonstrated that the gadolinium-core plastic scintillator sphere is a stable, highly sensitive, transportable, and cost-efficient neutron detector made of environmentally friendly components. This detector comprises a metal gadolinium core inserted at the center of a high-scale plastic scintillator sphere. In this study, we conducted simulations to investigate the feasibility of obtaining accurate neutron ambient dose equivalent measurements using this type of detector. The Geant4 code based on the Monte Carlo method was employed to calculate the detector light output spectra for different neutron energies and the response function of the high energy part above 3 MeVee. The neutron energy responses of the detector were combined in an appropriate manner to match the energy-dependent neutron fluence to the ambient dose equivalent conversion coefficients. The Monte Carlo simulation results were used to optimize the thickness of the metal gadolinium core and plastic scintillator. The simulation results showed that a metal gadolinium core with a thickness of several hundred microns is a suitable choice considering manufacturing costs and the detector's efficiency. In addition, this type of detector with the plastic scintillator sphere size of 8" can predict the neutron ambient dose equivalent with good accuracy over a wide energy range from 0.01 eV to 20 MeV, Although it underestimated the neutron dose equivalent in the energy range from 10 keV to about 5 MeV and overestimated it in the energy interval from 5 MeV to 20 MeV.