«= Pictures were obtained showing configuration of active materials on fou?primaries and two secondaries. project report. Further details will be given in the Program 13, Reaction History ” Program 13 measured alpha as a function of time for the fission de- vices and primaries in order to determine whether they worked properly,and in case they did not, to aide in diagnosing the trouble. I also made measurements indicating the ‘transit time" for the HE implosion and time from load ring pulse to very early gamma levels in the device. Alpha detectors, each consisting of a plastic fluor and photocell or photomultiplier combination in a light-tight can, were mounted at appropriate distances from the devices to give a wide range in sensitivity. The signals were conducted over coaxial cables, which were shielded against gamma, neutron, and electromagnetic radiation, to concrete bunkers. These signals then were displayed on a series of high speed oscilloscopes together with timing frequencies and were recorded by cameras. Similar detectors, very near the device, gave signals which were telemetered by a wide band ultra high frequency transmitter-receiver combination and recorded on oscilloscopes. For detaila on resulta of the alpha measurements the reader is referred to the project reports. Program 14, Phonex-Pinex The objective of Program 14 was to obtain neutron spectra at a number of positions on the secondary of a two-stage device. Neutrons were allowed to form an image of the source on a hydrogen-containing thin plastic foil by means of a pinhole placed in a mile-long vacuum pipe. Recoil protons from this foil passed through a collimating system and were recorded on nuclear emulsion plates. Tracks were counted and measured to determine the spectrum of the incident neutrons. Program 15, Photo-Physics Program 15 was conducted to obtain radius versus time data for hydrodynamic yield determinations, to determine the nature and behavior of a nuclear detonation by photographing the light produced during the initial stages of the detonation, and to study the reaction rate in the secondary of a two-stage device of megaton yield by meana of gammas and neutrons emitted from the secondary at various positions. Framing cameras were operated from several photo stations on each shot to record the growth of the fireball. Very high speed streak cameras were used to record the history of the light arising near the bomb in the first few microseconds. A pinhole in a mile-long vacuum pipe was used to collimate gamma rays and neutrons onto a plastic fluor. Light from the fluor was photographed with high speed streak cameras to record the gamma versus time history and the arrival rate of the neutrons. The latter makes possible the determination of the neutron spectrum at variouag places. 47