Liquid helium of liquid water. Helium was first liquefied on July 10, 1908, by the Dutch physicist Heike Kamerlingh Onnes at the University of Leiden in the Netherlands. At that time, helium-3 was unknown because the mass spectrometer had not yet been invented. In more recent decades, liquid helium has been used as a cryogenic refrigerant, and liquid helium is produced commercially for use in superconducting magnets such as those used in magnetic resonance imaging (MRI), nuclear magnetic resonance (NMR), Magnetoencephalography (MEG), and experiments in physics, such as low temperature Mössbauer spectroscopy. The temperature required to produce liquid helium is low because
Heike John Heike John Heike John (now Heike Walpot; born 19 June 1960) is a retired German swimmer and former astronaut candidate. She won a bronze medal at the 1977 European Aquatics Championships. She competed at the 1976 Summer Olympics in the 100 m and 200 m backstroke events but did not reach the finals. During her career she won five national titles in the 100 m (1977) and 200 m (1977, 1978) backstroke and 200 m medley (1977, 1978). She missed the 1980 Summer Olympics because of their boycott by West Germany. After her swimming career, she studied medicine at RWTH