A cryostat used in hole No. 12 of the graphite reactor at Oak Ridge National Laboratory is described in detail. The cryostat which is made almost entirely of aluminum is supplied with cold helium gas from an Arthur D. Little helium refrigerator. Bombardments have been made in the cryostat at temperatures as low as 15°K for periods as long as two weeks. A discussion of the equilibrium temperature attained by a specimen in the cryostat is given taking into account the reactor gamma ray heating effects. A method for measuring stored energy and specific heats of materials bombarded in the cryostat utilizing gamma ray heating is described. A method for pulse annealing specimens at low temperatures employing the discharge of the energy stored in a bank of condensers is also described. Relatively sharp and quite reproducible thermal pulses can be obtained with this method (which is also suitable for use in the laboratory). The hazard of cryogenic devices in high radiation fields is discussed. It is believed that when air is allowed to condense on a cold surface in the presence of intense ionizing radiations, a hazardous condition results.

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stored energy and specific heats of of condensers pulse annealing cryogenic devices gamma ray heating method discharge pulses ionizing

R. R. Coltman T. H. Blewitt T. S. Noggle,.Techniques and Equipment Utilized in Low‐Temperature Reactor Irradiations. 28 (5),375.

R. R. Coltman T. H. Blewitt T. S. Noggle,"Techniques and Equipment Utilized in Low‐Temperature Reactor Irradiations" 28

R. R. Coltman T. H. Blewitt T. S. Noggle,"Techniques and Equipment Utilized in Low‐Temperature Reactor Irradiations"