Neutron spectrum unfolding using a modified truncated singular valve decomposition method

A modified truncated singular value decomposition (MTSVD) is employed to un fold proton recoil pulse-height spectra into neutron energy spectra, using experimentally measured response functions. To illustrate the method, spect ra from Cf-252 and (PuBe)-Pu-239 sources are unfolded. The relative error, defined in terms of the I-norm, using the MTSVD method is found to be appro ximately half that of the truncated singular value decomposition for the Cf -252 spectra. Relative errors for the (PuBe)-Pu-239 spectra were approximat ely equal for the two methods. The method is limited by the precision of th e measurement of the response functions and the pulse-height spectra. More precise measurements would allow the use of larger truncation parameters an d are likely to result in more accurate reconstructed neutron spectra. The MTSVD method is particularly suited to real-time on-line unfolding of spect ra.