Lo Project 31.2a = Temperature vs Time Inside Fireball by Electronics - F. E. Thanpson - SC 2.2% = Temperature ve Time Inside Fireball by Guns The primary objective of these is to measure the removal of materials from metal surfaces inside the fireball. We have two schemes set up for making these measurements. The first one considered is the erection of a steel column inside the tower of the Kickapoo shot. We will mount metal samples at 20' intervals on this colunn, the first samples being 10' below the device. We'll have three types of metals - aluminum, copper and steel, as presently planned. On each of these samples we will have two types of gauges or switches, as it turns out, located at two different depths; in other words, four probes in each of the three metals, or a total of 12 channels at each station, with a total of eight stations. This gives us a total of 96 channels fran which we will record on a magnetic tape which is housed in the shelter at the base of the tower. The recording system will not include any electronics - we will employ a method of erasing apre-recorded signal by an electronic current which is initiated or terminated by the switches in the metal samples. We anticipate some difficulties with possible ionization of cables and ionization of gaps in the normal open probes. We are running some tests now at the Materials Testing Reactor in Idaho Palls to determine the effects of radiation on the electrical cables that we intend to use in the steel colum. We expect to minimize the electrical transient somewhat by having the entire recording system isolated from ground and having the entire system grounded only at one point - at the point of the shield at the probe on the tower. We are also running some tests as to the effects of nuclear radiation on magnetic tape. So far we have subjected tapes and cable to gamma fields of 6 x 10° r/nr and have noticed no il) effects. The second type of measurement which we propose is the firing of projectiles from recoilless rifles mounted on the same tower. We plan to mount three 75—mm recoilless rifles as near as possible to the top of the tower, firing vertically downward. Two more will be mounted approximately 100! below the cab, also firing downward. For one of the three mounted at the top we will attempt to catch the projectile in a barrel located some 15' below the rifle, another one of the projectiles fired from the top we'll attempt to catch about 125' below the rifle, and the third one we'll catch on the ground. For the two rifles mounted at the 100! station, we will attempt to catch one of the projectiles at about 25' below the rifle and the other one on the ground. The nose section of the projectiles will consist of segments of copper, aluminum and steel and we hope that in this way we can measure the degree of metal removal by the thermal effects of the fireball for different integral portions of the fireball. In other words, the projectile is fired from the top. If we can catch it and shield 4t 15' below the rifle from any further thermal effects, we'll be able to find out how much of the metal is removed during the early portions of the fireball - and the other arrangement will give us different integral portions.