ENERGY SPECTRA OF RADIOACTIVE NEUTRON SOURCES by Dr. A.H.W. Aten Jr The work described in this thesis is part of the research program of the Institute for Nuclear Research (I.K.O.),made possible by financial support from the Foundation forFundamental Research on Matter (F.0.M) and the NetherlandsOrganization for the Advancement of Pure Research (Z.W.O.). ...