rt One project, sponsored by AFCRC, tested two systems for accurately locating GZ from long-range stations by measurement of the electromagnetic pulse generated by the nuclear detonations. Installed were four groups of stations, consisting of one long baseline and one short baseline in the Hawaiian area, one short baseline in the San Francisco area, and one long baseline in the Eastern United States. The short baseline system was tested for ability to determine a hyperbolic Mne of position by use of the inverse LORANprinciple. The long baseline system was tested for the capability of each network to develop two hyperbolic lines of position which would give a fix on GZ. Preliminary results show that under the conditions of this test, where the expected yield and time of detonation are known, the detonation point of nuclear devices in the yield range obtained on Redwing could be accurately located at long ranges by this method. However, there are yet many problems to be solved before a continuous monitoring system is feasible. - In another project, Evans Signal Laboratory and AFCRC investigated the effect of nuclear detonations upon the fonosphere. The results of this purely scientific research effort have no immediate applicable military value. The high-yield detonations produced notable changes upon the fonosphere and. upon the absorption of vertically transmitted radio waves, whereas small detonations had no observed effect. Ultrasonics Corporation tested airborne flush-mounted ferrite-core antennas and phototubes for yield determination. These components are to ‘ - become a part of a Bhangmeter which is to be required equipment in the weaponsystem of the supersonic B-58 aircraft. It is considered feasible to use this unit, with some modification, for determining yield from aircraft. ESL recorded the wave form of the electromagnetic pulse emanating from a nuclear detonation. The laboratory will correlate the wave-form parameters with the height and yield of detonations. This information is to be used as a basis for developing a tactical IBDA system to meet the requirements of the U. S. Army. The Naval Research Laboratory measured microwave attenuation as a function of time in the ionization region resulting from a nuclear detonation. This information is of value in the development of a telemetering link for transmitting technical information from a high-altitude nuclear detonation. 2.1.7 Program 8, Thermal Effects . The primary objectives of Program 8 were (1) to make basic thermal radiation measurements with which to study the radiating properties of the fireball; (2) to determine, for further laboratory studies, critical ignition energies for cellulosic materials exposed to the relatively—long-duration - 35 - AFWLS HL . 33