SievertThe sievert (symbol: Sv) is a unit in the International System of Units (SI) intended to represent the stochastic health risk of ionizing radiation, which is defined as the probability of causing radiation-induced cancer and genetic damage. The sievert is important in dosimetry and radiation protection. It is named after Rolf Maximilian Sievert, a Swedish medical physicist renowned for work on radiation dose measurement and research into the biological effects of radiation.
Neutron starA neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses (), possibly more if the star was especially metal-rich. Except for black holes, neutron stars are the smallest and densest currently known class of stellar objects. Neutron stars have a radius on the order of and a mass of about . They result from the supernova explosion of a massive star, combined with gravitational collapse, that compresses the core past white dwarf star density to that of atomic nuclei.
Neutron bombA neutron bomb, officially defined as a type of enhanced radiation weapon (ERW), is a low-yield thermonuclear weapon designed to maximize lethal neutron radiation in the immediate vicinity of the blast while minimizing the physical power of the blast itself. The neutron release generated by a nuclear fusion reaction is intentionally allowed to escape the weapon, rather than being absorbed by its other components.
Radiation hormesisRadiation hormesis is the hypothesis that low doses of ionizing radiation (within the region of and just above natural background levels) are beneficial, stimulating the activation of repair mechanisms that protect against disease, that are not activated in absence of ionizing radiation. The reserve repair mechanisms are hypothesized to be sufficiently effective when stimulated as to not only cancel the detrimental effects of ionizing radiation but also inhibit disease not related to radiation exposure (see hormesis).
RadiobiologyRadiobiology (also known as radiation biology, and uncommonly as actinobiology) is a field of clinical and basic medical sciences that involves the study of the action of ionizing radiation on living things, especially health effects of radiation. Ionizing radiation is generally harmful and potentially lethal to living things but can have health benefits in radiation therapy for the treatment of cancer and thyrotoxicosis. Its most common impact is the induction of cancer with a latent period of years or decades after exposure.
Neutron generatorNeutron generators are neutron source devices which contain compact linear particle accelerators and that produce neutrons by fusing isotopes of hydrogen together. The fusion reactions take place in these devices by accelerating either deuterium, tritium, or a mixture of these two isotopes into a metal hydride target which also contains deuterium, tritium or a mixture of these isotopes. Fusion of deuterium atoms (D + D) results in the formation of a helium-3 ion and a neutron with a kinetic energy of approximately 2.
Neutron star mergerA neutron star merger is a type of stellar collision. When two neutron stars orbit each other closely, they gradually spiral inward due to gravitational radiation. When the two neutron stars meet, their merger leads to the formation of either a more massive neutron star, or a black hole (depending on whether the mass of the remnant exceeds the Tolman–Oppenheimer–Volkoff limit). The merger can also create a magnetic field that is trillions of times stronger than that of Earth in a matter of one or two milliseconds.
Neutron radiationNeutron radiation is a form of ionizing radiation that presents as free neutrons. Typical phenomena are nuclear fission or nuclear fusion causing the release of free neutrons, which then react with nuclei of other atoms to form new nuclides—which, in turn, may trigger further neutron radiation. Free neutrons are unstable, decaying into a proton, an electron, plus an electron antineutrino. Free neutrons have a mean lifetime of 887 seconds (14 minutes, 47 seconds). Neutron radiation is distinct from alpha, beta and gamma radiation.
Lockheed Martin Compact Fusion ReactorThe Lockheed Martin Compact Fusion Reactor (CFR) is a fusion power project at Lockheed Martin’s Skunk Works. Its high-beta configuration, which implies that the ratio of plasma pressure to magnetic pressure is greater than or equal to 1 (compared to tokamak designs' 0.05), allows a compact design and expedited development. The project was active between 2010 and 2019, after that date there have been no updates and it appears the division has shut down.
Model aircraftA model aircraft is a small unmanned aircraft. Many are replicas of real aircraft. Model aircraft are divided into two basic groups: flying and non-flying. Non-flying models are also termed static, display, or shelf models. Aircraft manufacturers and researchers make wind tunnel models for testing aerodynamic properties, for basic research, or for the development of new designs. Sometimes only part of the aircraft is modelled.
