Keesom, Willem Hendrik

Willem-Hendrik Keesom (Keesom, Willem Hendrik)
(1876-1956)

Willem-Hendrik Keesom - Netherlands physicist. Born June 21, 1876, Mr.. Texel in the family farmer. In 1900, Mr.. graduated from the University of Amsterdam, where one of his mentors was the Van der Waals, and in 1904. defended his doctoral thesis on the construction of the isotherms of mixtures of oxygen with carbon dioxide. Since 1900. by 1909. worked at the University of Leiden, was the closest assistant Onnes: in 1908. with him for the first time received a liquid helium in 1912. written an exhaustive review of the equation of state for mathematical encyclopedia. In 1909, Mr.. Keesom moved to the University of Utrecht, where he held extensive experimental studies on X-ray diffraction on the liquid molecules and the determination of intermolecular distances. In 1917, Mr.. was appointed lecturer in 1918. - Professor of Experimental Physics. In 1923, Mr.. returned to the University of Leyden in Professorship, and in 1926. became director of the cryogenic laboratory, which is inherited from the Kamerlingh Onnes.

In Leiden Keesom again turned to the low-temperature studies. Measured the temperature of boiling liquid helium (4,126 K), the elasticity of its vapors, dielectric constant, surface tension, thermal conductivity, heat of fusion, compressibility, viscosity. In 1926, Mr.. first received solid helium.

In 1928, Mr.. with M. Volfke discovered in liquid helium at 2, . 19 K phase transition of type II, . resulting in a sudden change of thermal conductivity and the evidence of low temperature helium in two modifications: above the critical temperature is Helium I, . below - Helium II,
. In 1931-1932 he. pumping vapors of liquid helium was a record low temperature of 0.71 K. In 1935. first discovered an unusually high thermal conductivity of helium II (later Kapitza showed experimentally that helium II is not characterized by abnormally high thermal conductivity, and the absence of viscosity - superfluidity). In 1938. Keesom was the first X-ray crystal of solid helium. In 1942, Mr.. wrote a monograph on the physical properties of helium at low temperatures, in 1945. resigned.

Died Keesom in Leiden, March 24, 1956