Rugged, self-recording gauges had been developed for blast and thermal radiation measurements by 1954 so that complete loss of data from a project would not occur heavy fallout. if instrument recovery were delayed, for example, by For nuclear radiation measurements, however, prompt data recovery was still desirable because the gauges used might be thin foils of material that would be made radioactive by the burst-time neutrons; hence, early observation was necessary, before the information contained in the induced radiation pattern decayed away. The potential for radiation exposure of personnel responsible for environmental measurements in general depended on their proximity to the device and the time that elapsed between detonation and instrument recovery, as was the case for weapon development experimentation: the nearer in space or time to the detonation, the greater the potential for exposure. SYSTEMS RESPONSE EXPERIMENTS. To document the response of systems to the hostile environment, military hardware (such as aircraft or naval mines) was exposed to the effects of nuclear detonations. The techniques used for ‘the systems response experiments were conceptually simple: response. exposure of the system of interest and observation of its Actual conduct of the experiments was far more complex. The level of the threat to which the system was exposed almost always required documentation so that the response could be properly understood, necessitating an environmental experiment along with the systems response experiment. It was often not enough to know whether the system survived, but rather, the response of the component parts and their interactions was required, entailing the placement of sophisticated instrumentation and recording devices. While the potential radiological exposure for these systems response experiments was governed primarily by the closeness in space or time, an additional problem arose. Often, when the subject of the exposure itself was recovered for closer examination, it could be contaminated by device 36