DUKE UNIVERSITY WILL PERFORM MEASUREMENTS OF THE DIFFERENTIAL ANGLE AND ENERGY OF THE PROMPT NEUTRON YIELD FROM PHOTON-INDUCED FISSION AT DISCRETE GAMMA-RAY BEAM ENERGIES AROUND THE GDR. THE RESEARCH WILL BUILD ON THE EXPERIMENTAL TECHNIQUES, EXPERIMENT SETUP, AND EXPERIENCE GAINED IN PERFORMING PHOTO-NEUTRON MEASUREMENTS AT HIGS DURING THE CURRENT GRANT PERIOD. THEY HAVE PERFORMED THE FIRST DIFFERENTIAL MEASUREMENTS OF NEUTRONS EMITTED FROM PHOTON-INDUCED REACTIONS ON ACTINIDE NUCLEI AT DISCRETE BEAM ENERGIES. THESE MEASUREMENTS WERE CONDUCTED AT BEAM ENERGIES OF 11.2 AND 13.5 MEV WHERE THE FISSION CROSS SECTION IS LARGEST. THEY PROPOSE TO EXTEND THE MEASUREMENTS TO ENERGIES ON EITHER SIDE OF THE GDR AT 10, 16 AND 18 MEV. THE ANGULAR DISTRIBUTION OF THE PROMPTLY EMITTED NEUTRONS WILL BE MEASURED OVER THE REACTION ANGLE RANGE FROM 22.5° TO 157.5° IN 22.5° STEPS. NEUTRON ENERGY SPECTRA WILL BE ACCUMULATED IN 200-KEV BINS AT EACH ANGLE, AND THE ABSOLUTE CROSS SECTION FOR THE (¿, XN) REACTIONS AND THE NEUTRON YIELDS FOR THE (¿, FN) REACTION WILL BE DETERMINED TO A SYSTEMATIC UNCERTAINTY BETTER THAN ±5%. THE (¿, FN) MEASUREMENTS ARE PERFORMED USING THIN TARGETS MOUNTED INSIDE AN IONIZATION CHAMBER THAT TAGS THE FISSION EVENT-BY-EVENT.