[en] Technique of neutron spectra unfolding in the energy range 10^-8-15 MeV simultaneously from readings of the neutron activation detectors: resonance, threshold and thermal detectors in polyethylene sphere moderators by the statistical regularization method (SRM) is described. The case, when apriori information on spectrum except of the information on smoothing of the spectrum is practically unknown, is considered; any kind of spectrum interpolation is expelled. The influence of a number of detectors used on the results of unfolding neutron spectra is analyzed, is well as those on meanings of fluences, doses rates equivalent and absorbed doses rates. Obtained results confirm the possibility of reliable unfolding of neutron spectra in a wide energy range by the SRM even when data from the activation detectors are given with the 15% standard deviation