## LANSCE (Manuel Lujan, Jr. Neutron Scattering Center) target system performance

We measured neutron beam fluxes at LANSCE using gold foil activation techniques. We did an extensive computer simulation of the as-built LANSCE Target/Moderator/Reflector/Shield geometry. We used this mockup in a Monte Carlo calculation to predict LANSCE neutronic performance for comparison with measured results. For neutron beam fluxes at 1 eV, the ratio of measured data to calculated varies from /approx/0.6-0.9. The computed 1 eV neutron leakage at the moderator surface is 3.9 /times/ 10/sup 10/ n/eV-sr-s-/mu/A for LANSCE high-intensity water moderators. The corresponding values for the LANSCE high-resolution water moderator and the liquid hydrogen moderator are 3.3 and 2.9 /times/more »