Cryostats for Irradiating at 4.2°K
Low-temperature irradiation experiments on metals and semiconductors have been important recently in the study of lattice defects in these materials. It is the purpose of this paper to describe two cryostats, one for semiconductors and the other for metals, which have been used for electron irradiations at liquid-helium temperature and for subsequent annealing of the sample in situ. The factors determining the design of the cryostats are somewhat different in the two cases mentioned. However, basically the same type of heater and temperature control system is used in both cryostats. Also, the good low-temperature thermal conductivity of sapphire is used in both devices to provide an element which is a thermal conductor and an electrical insulator. The ability to fabricate such elements from sapphire is critical to the performance of both cryostats.
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