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Helium-3 (3 He [1] [2] see also helion) is a light, stable isotope of helium with two protons and one neutron. (In contrast, the most common isotope, helium-4, has two protons and two neutrons.) Helium-3 and protium (ordinary hydrogen) are the only stable nuclides with more protons than neutrons. It was discovered in 1939.
Extraplanetary material, such as lunar and asteroid regolith, has traces of 3 He from solar wind bombardment. To become superfluid, 3 He must be cooled to 2.5 millikelvin, ~900 times lower than 4 He (2.17 K). This difference is explained by quantum statistics: 3 He atoms are fermions, while 4 He atoms are bosons, which condense to a superfluid ...
Similar cooling of helium-3, which has a lower boiling point, can achieve about 0.2 kelvin in a helium-3 refrigerator. Equal mixtures of liquid 3 He and 4 He below 0.8 K separate into two immiscible phases due to their dissimilarity (they follow different quantum statistics: helium-4 atoms are bosons while helium-3 atoms are fermions). [30]
Only about one helium-3 atom exists for every million helium-4 atoms, Horton said. The team measured about 10 million helium-3 atoms per gram of olivine crystals.
Helium 3 is rare on Earth, primarily produced by the radioactive decay of tritium, but it does reside in abundance in the lunar regolith, deposited by billions of years of solar wind. The isotope ...
Helium has two abundant isotopes: helium-3, which is primordial with high abundance in earth's core and mantle, and helium-4, which originates from decay of radionuclides (232 Th, 235,238 U) abundant in the earth's crust. Isotopic ratios of helium are represented by R A value, a value relative to air measurement (3 He/ 4 He = 1.39*10 −6). [98]
Liquid helium is a physical state of helium at very low temperatures at standard atmospheric pressures.Liquid helium may show superfluidity.. At standard pressure, the chemical element helium exists in a liquid form only at the extremely low temperature of −269 °C (−452.20 °F; 4.15 K).
3 Surprising Facts You Probably Didn't Know About Hummingbirds. Patricia S York. September 7, 2024 at 10:00 AM ... Elton John reveals which of his own songs are his favorites — and which one he ...