PREFACE Although the major portion of the experimental plan, design and fabrication of instrument: was done by the Nucleonics Division personnel who participated in the field, the timely completion of the printed circuitry and the solution of circuit problems could not have oc- curred without the aid of the Instrumentation Branch of the Radiation Division of Naval Research Laboratory (NRL). In particular major contributions were made by G. Wall, P. Shifflett, W. Weedman, G. Brotzman, and L. Bowles.