Search results
Results from the WOW.Com Content Network
An atom consists of a small, heavy nucleus surrounded by a relatively large, light cloud of electrons. An atomic nucleus consists of 1 or more protons and 0 or more neutrons. Protons and neutrons are, in turn, made of quarks. Each type of atom corresponds to a specific chemical element. To date, 118 elements have been discovered or created.
An estimate puts the needed temperature at (1.90 ± 0.02) × 10 12 kelvin. [100] While a state of entirely free quarks and gluons has never been achieved (despite numerous attempts by CERN in the 1980s and 1990s), [ 101 ] recent experiments at the Relativistic Heavy Ion Collider have yielded evidence for liquid-like quark matter exhibiting ...
The W bosons are known for their mediation in nuclear decay: The W − converts a neutron into a proton then decays into an electron and electron-antineutrino pair. The Z 0 does not convert particle flavor or charges, but rather changes momentum; it is the only mechanism for elastically scattering neutrinos.
A proton is made of two up quarks and one down quark, while the neutron is made of two down quarks and one up quark. These commonly bind together into an atomic nucleus, e.g. a helium-4 nucleus is composed of two protons and two neutrons.
The best known baryons are protons and neutrons, which make up most of the mass of the visible matter in the universe, whereas electrons, the other major component of atoms, are leptons. Each baryon has a corresponding antiparticle , known as an antibaryon, in which quarks are replaced by their corresponding antiquarks.
To create an electron-positron pair, the total energy of the photons, in the rest frame, must be at least 2m e c 2 = 2 × 0.511 MeV = 1.022 MeV (m e is the mass of one electron and c is the speed of light in vacuum), an energy value that corresponds to soft gamma ray photons.
The atom helium-3 (3 He) consists of two protons, one neutron, and two electrons. The deuterium atom consists of one proton, one neutron, and one electron. The number of bosons within a composite particle made up of simple particles bound with a potential has no effect on whether it is a boson or a fermion.
The name boson was coined by Paul Dirac [3] [4] to commemorate the contribution of Satyendra Nath Bose, an Indian physicist. When Bose was a reader (later professor) at the University of Dhaka, Bengal (now in Bangladesh), [5] [6] he and Albert Einstein developed the theory characterising such particles, now known as Bose–Einstein statistics and Bose–Einstein condensate.