“…The commonest tool used in the investigation of photo nuclear reactions is the high energy electron accelerator, although the recent (10,11,12,13,14) development of practical photon monochromators offers the hope of a more powerful weapon. The earliest utilization of an accelerator was by Baldwin and Klaiber (15) who were the first to notice the resonance shape of the cross section when they determined the C^(T^n) and Cu^(X,n) yields by measuring the radio activity of the daughter nuclei.…”