Low Temperature
In physics, cryogenics is the production and behaviour of materials at very low temperatures. The 13th IIR International Congress of Refrigeration endorsed a universal definition of "cryogenics" and "cryogenic" by accepting a threshold of 120 K to distinguish these terms from the conventional refrigeration. This is a logical dividing line, since the normal boiling points of the so-called permanent gases lie below 120K while the Freon refrigerants, hydrocarbons, and other common refrigerants have boiling points above 120K. The U.S. National Institute of Standards and Technology considers the field of cryogenics as that involving temperatures below -153 Celsius Discovery of superconducting materials with critical temperatures significantly above the boiling point of nitrogen has provided new interest in reliable, low cost methods of producing high temperature cryogenic refrigeration.
