Study on a temperature scale from 24,5561 K to 273,16 K by comparison calibration

A comparison calibration apparatus using a GM cryocooler was developed. This apparatus has the structure that temperature changes of the cryocooler do not conduct directly to improve the temperature stability. A practical temperature scale from 24,5561 K to 273,16 K was examined by using the comparison calibration apparatus. Generally, a standard platinum resistance thermometer (SPRT) is calibrated at the triple points of hydrogen, neon, oxygen, argon, mercury and water in the international temperature scale of 1990 (ITS-90) for this temperature range. In this work, a capsule type SPRT was calibrated by comparison calibration method at the temperature close to these fixed point temperature. And the temperature scale using the results of the comparison calibration was compared with the temperature scale defined in the ITS-90. As a result, two temperature scales corresponded within 1,5 mK.