The final assembly of the Linac was completed and it was placed in operation. The major difficulty encountered has to do with limited cathode emission. In order to solve this problem, the entire vacuum system was reworked and a cathode research program was begun. Development and studies were continued on equipment for neutron capture cross section measurements, neutron slow-chopper spectra measurement equipment, neutron die-away experiment targets, the REX code, time-dependent transport theory, time-dependent spectra in infinite media, time- dependent water spectra, cylindrical cell boundary conditions, IBM704 codes for neutron thermalization studies, space and energy distribution of thermal neutrons, and effective mass kernels in neutron thermalization studies. (M.C.G.)