Liquid Helium Temperatures in an Atomic Reactor
Fundamental studies of the basic nature of radiation effects have been conducted in the Oak Ridge National Laboratory graphite reactor by the Low Temperature Group of the Solid State Division. It was discovered that many radiation induced defects were not observed at room temperature because they thermally anneal at much lower temperatures. Measurements of radiation induced changes in electrical resistivity, yield stress, and stored energy in copper and aluminum single crystals were made at sample temperatures as low as 15°K. Subsequent annealing studies show that about 50 per cent of the change in electrical resistivity is recovered between 28 and 50°K. This appears to be the result of radiation induced defects escaping from low energy traps.1,2 It is particularly advantageous, when measuring electrical resistance of these metals, to be able to bombard them below 20°K because the change of resistance with temperature is small for many metals in this temperature region.
KeywordsRadiation Induce Defect Radiation Induce Change Expansion Valve Cryogenic Engineer Cold Case
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