SPIDER: A scalable fission product spectrometer for measurements with fast neutrons at LANSCE

New developments have been made in the SPIDER (Spectrometer for Ion Determination in fission Research) project toward a large-acceptance system. The goal of SPIDER is to measure Fission Product Yields (FPYs) consistently as a function of incident neutron energy using the Weapons Neutron Research (WNR) facility at the Los Alamos Neutron Science Center (LANSCE). SPIDER uses the 2E-2v technique to extract the mass of the fission fragments directly by measuring their time-of-flight and energies. By measuring the masses of both fragments directly and in coincidence, one can measure directly the number of neutrons emitted as a function of both fragment mass and incident neutron energy. The design requirements are strongly driven by the difficulty to measure the absolute kinetic energies of fission fragments with varying mass, charge, and kinetic energy, and challenges related to absolute calibrations. For the purposes of energy calibration, a gamma-ray tagging technique has been developed and implemented using 252Cf(sf) sources and HPGe detectors and a two-arm prototype system. The final design of a multi-arm system will be discussed, as well as recent progress in construction and fielding of this system.