Characterization of a C6D6 Liquid Scintillation Detector with Monoenergetic Neutrons

Recently, C6D6 detectors have been studied for applications such as nuclear nonproliferation and nuclear safeguards. The neutron pulse-height distribution from a standard liquid scintillator contains information about the energy spectrum of the incident neutrons. However, there is no unique, non-probabilistic relation between incident neutron energy and measured pulse height. Therefore, the energy-spectrum unfolding results in an ill-posed, inverse problem which has been approached in numerous ways with some success. One difficulty with unfolding spectra using standard hydrogen-based scintillators is that neutron scattering on hydrogen is isotropic, and has no “preference” regarding energy transferred in a collision. Neutron scattering on deuterium, is non-isotropic, which might lead to more accurate unfolding results. To reveal the potential of C6D6 detectors their detailed properties need to be accurately obtained. In this paper, detailed measurement results with monoenergetic neutron beams with energies between 5 and 20 MeV are presented. The objective of this work is to characterize the detector’s response to various neutron energies. These measured results were used to obtain an appropriate energy-to-light-output conversion curve, which is essential for performing high-fidelity Monte Carlo simulations. The measurement results are supported by MCNPX-PoliMi simulations performed for various experimental configurations, using experimentally obtained energy-to-light conversion curve.