[en] Progress is reported here for the period January 1, 1978 to September 15, 1978. During this time effort was devoted to three areas: measurements of the delayed neutron equilibrium spectrum of ²⁴⁰Pu, neutron transport calculation for the design of a flat-response neutron detector assembly, and design and apparatus development for the flat-response neutron detector assembly. Work in the first two categories is now complete. A delayed neutron spectrum for ²⁴⁰Pu was measured, and this represents the first such measurement that has been performed. Transport calculations show that a graphite assembly approximating a sphere of radius 60-cm and containing a 5-cm Be shell adjacent to a central neutron source should be a flat-response detector assembly with impressive performance. If measurements agree with the calculations, this assembly will have an efficiency that is almost independent of neutron energy up to about 8 MeV. 3 figures