Replacement of Bonner spheres with polyethylene cylinders for the unfolding of an 241Am-Be neutron energy spectrum

In this study, a conventional Bonner sphere spectrometer, together with 6LiI(Eu) inorganic scintillator used as the central detector, was used to obtain the neutron energy spectrum of an 241Am-Be source. To achieve this, we calculated the response matrices corresponding to eight different sizes of polyethylene spheres for the neutron energies ranging from about 10−7 to 15 MeV in 54 energy groups by using the MCNPX2.6 code, and the 241Am-Be neutron spectrum was obtained using a modified version of the neutron spectrum unfolding code, AFITBUNKI. In a feasibility study, similar calculations were performed with different sizes of polyethylene cylinders. A comparison between the unfolded spectra of a typical 241Am-Be neutron source with those of Bonner spheres, cylinders of similar sizes, and standard 241Am-Be neutron energy spectra shows that the spectrometer with polyethylene cylinders can be used as a potential alternative for conventional Bonner spheres.