Joannes Theodorus Maria (Jook) Walraven (born August 20, 1947,

Amsterdam Amsterdam ( , , , lit. ''The Dam on the River Amstel'') is the Capital of the Netherlands, capital and Municipalities of the Netherlands, most populous city of the Netherlands, with The Hague being the seat of government. It has a population ...

) is a Dutch experimental physicist at the Van der Waals-Zeeman Institute for experimental physics in Amsterdam. From 1967 he studied physics at the University of Amsterdam. Both his doctoral research and PhD research was with Isaac Silvera, on the subject of Bose-Einstein Condensation. Because of the difficulty of his research subject, his promotion took six years instead of four. The aim of his PhD research was to make a gas of atomic hydrogen, which could become the world's first quantum gas. This might then be a suitable candidate for a Bose-Einstein Condensate (BEC). In order to achieve this state, the gas of atomic hydrogen would have to be cooled to only a few

Kelvin The kelvin, symbol K, is the primary unit of temperature in the International System of Units (SI), used alongside its prefixed forms and the degree Celsius. It is named after the Belfast-born and University of Glasgow-based engineer and phys ...

, without recombining to molecular hydrogen. Jook Walraven developed a method of

evaporative cooling An evaporative cooler (also known as evaporative air conditioner, swamp cooler, swamp box, desert cooler and wet air cooler) is a device that cools air through the evaporation of water. Evaporative cooling differs from other air conditioning sy ...

: a tank was filled with a gas of atomic hydrogen, from which the 'hottest' (fastest) atoms were removed. This resulted in a lower temperature of the whole gas. To keep the atomic hydrogen from forming hydrogen molecules, the atoms were spin-polarized by a 7 tesla magnet. In a few years, Silvera and Walraven had achieved the first quantum-gas. However, due to interactions with the wall of the tank, the gas did not cool enough to reach the critical temperature at which it condenses into a BEC. In the meantime, several other groups had started to do research on the subject, some of which were actually doing research in laser science. Two of these groups managed to achieve the first BEC in 1995 by using evaporative cooling in combination with

laser cooling Laser cooling includes a number of techniques in which atoms, molecules, and small mechanical systems are cooled, often approaching temperatures near absolute zero. Laser cooling techniques rely on the fact that when an object (usually an atom) ...

. In 1996 Jook Walraven was offered the position of director at AMOLF, which he accepted. He decided to change fields to laser science, and achieved his first BEC a few years later. In November 2005, Jook Walraven was elected a fellow of the

American Physical Society The American Physical Society (APS) is a not-for-profit membership organization of professionals in physics and related disciplines, comprising nearly fifty divisions, sections, and other units. Its mission is the advancement and diffusion of k ...

(APS), "for pioneering experimental and theoretical contributions to the physics of quantum gases".

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* {{DEFAULTSORT:Walraven, Jook 1947 births Living people 20th-century Dutch physicists Scientists from Amsterdam