Abstract: The principle and structure of the single sphere neutron spectrometer based on a spherical polyethylene moderator with 19 pairs of ⁶Li and ⁷Li scintillation detectors was described in this paper. Calculated neutron response functions by Monte Carlo Neutron-particle Transport Code showed that this spectrometer has good spatial symmetry, and the source location can be estimated by detector’s counts. Simulated spectrometer was exposed in ²⁴¹Am-Be radiation field to obtain counts of each detector and to unfold the simulated results by using Unfolding with Maxed and Gravel (UMG) code to get the energy spectrum. Different algorithms and default spectrum were considered in unfolding process. Compared with expected spectrum, the spectrum unfolded by default spectrum of ²⁴¹Am-Be standard source and maximum entropy method is the most accurate. The accuracy of response function is verified.

Key words: single sphere neutron spectrometer, monte carlo simulation, ⁶Li and ⁷ Li scintillator detectors, energy response, spectrum unfolding