Precise Realization of The Triple Points of Equilibrium Hydrogen and Argon Using A Closed Cycle Refrigerator

摘要

The triple points of equilibrium hydrogen and argon are calorimetrically realized using a closed cycle refrigerator. The usage of the closed cycle refrigerator with closed fixed-point cells is found not only to be the easiest and the simplest method in realizing low temperature fixed points, but also to be used for the most accurate measurement. By the results of high accurate calorimetry, abnormality in the heat capacity of solid hydrogen is observed at temperatures just below the triple point when a catalyst of ferric hydroxide is used for the equilibration of ortho-and para-hydrogen molecular modifications.