All articles starting with N
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Neutralizing antibody
Neutralizing antibody: an antibody that blocks viral entry into cells; measured by live-virus (PRNT, CPE) and pseudovirus assays, used as a correlate of protection and as therapeutic and prophylactic antiviral agents.
Neutrino
A neutrino is an electrically neutral fundamental particle with a small nonzero mass, known through three flavors, and the second most abundant particle in the universe after photons.
Neutrino astronomy
Neutrino astronomy observes cosmic neutrinos, which escape dense sources that block light, using huge detectors like IceCube, which discovered extraterrestrial high-energy neutrinos in 2013 and traced them to the blazar TXS 0506+056.
Neutrino Conference
The Neutrino Conference, officially NEUTRINO, is the biennial International Conference on Neutrino Physics and Astrophysics, recognized from 1972 at Balaton, Hungary, with preludes in 1965, 1968, and 1970, rotating worldwide.
Neutrino detector
A neutrino detector is an instrument that observes neutrinos, particles interacting only through the weak force; because interactions are extremely rare, detectors are massive and buried underground.
Neutrino mass (absolute scale and ordering)
The absolute scale of neutrino mass remains unmeasured; oscillation experiments fix mass splittings but not the overall scale, probed by KATRIN, cosmology, and neutrinoless double beta decay.
Neutrino oscillation
Neutrino oscillation, also called neutrino mixing, is the quantum-mechanical phenomenon in which a neutrino changes flavor as it travels; its discovery in 1998 earned the 2015 Nobel Prize in Physics.
Neutrinoless double beta decay (νββ)
Neutrinoless double beta decay (νββ) is a hypothetical radioactive decay in which a nucleus emits two electrons and no neutrinos, which would show that neutrinos are Majorana particles.
Neutrogena
Neutrogena is an American skincare brand founded in 1930 in Los Angeles around a gentle amber facial soap, built on dermatologist recommendations, and owned by Kenvue since 2023.
Neutron
The neutron is an electrically neutral subatomic particle that, together with the proton, makes up atomic nuclei, and decays outside them; it was discovered by James Chadwick in 1932.
Neutron activation
Neutron activation is the process in which nuclei capture neutrons and become radioactive isotopes, enabling neutron activation analysis, a highly sensitive elemental technique first reported by Hevesy and Levi in 1936.
Neutron activation analysis
Neutron activation analysis (NAA) is an analytical technique that determines which elements a sample contains by irradiating it with neutrons and measuring the characteristic gamma rays emitted.
Neutron bomb
The neutron bomb, formally an enhanced radiation weapon (ERW), is a low-yield thermonuclear warhead conceived by Samuel T. Cohen in 1958 that kills through neutron radiation rather than blast.
Neutron capture
Neutron capture, also called neutron absorption, is a nuclear reaction in which a nucleus absorbs a free neutron, forming a heavier isotope that usually emits gamma rays.
Neutron capture therapy of cancer
Neutron capture therapy of cancer (BNCT): radiation therapy injecting boron-10 drugs that collect in tumors, then irradiating with neutrons; 10B(n,alpha)7Li reaction, Hatanaka's 58% 5-year GBM survival, Japan 2020 insurance approval.
Neutron cross section
A neutron cross section is an effective area measuring the probability of a particular reaction between a neutron and a nucleus, expressed in barns of 10⁻²⁴ cm².
Neutron detection
Neutron detection is the indirect measurement of free neutrons, which carry no charge, using converter isotopes like helium-3, boron-10, and lithium-6 in gas-filled, scintillator, or semiconductor detectors.
Neutron diagnostics
Neutron diagnostics are the instruments in a fusion device that measure neutrons produced by fusion reactions, providing real-time measurement of fusion power, plasma ion temperature, and fast-ion behavior.
Neutron diffraction
Neutron diffraction is an experimental technique that scatters neutrons from a material's crystal lattice to determine atomic positions and magnetic order, locating light atoms like hydrogen that X-rays miss.
Neutron electric dipole moment
The neutron electric dipole moment (nEDM) measures charge separation along the neutron's spin axis. A nonzero value would signal new CP violation, but experiments have found none.
Neutron embrittlement
Neutron embrittlement, also called irradiation embrittlement, is the loss of fracture toughness and ductility caused by neutron radiation, a key aging mechanism of reactor pressure vessels.
Neutron emission
Neutron emission is a nuclear decay or reaction process in which an atomic nucleus releases neutrons, whether promptly from excited fission fragments or after beta decay of neutron-rich nuclei.
Neutron flux
Neutron flux is defined as the number of neutrons crossing a unit area per time. This quantity is the central element in reactor physics linking population to reaction rates.
Neutron generator
A neutron generator is a small accelerator that produces neutrons by fusing hydrogen isotopes, used in oil well logging, elemental analysis, security screening, and nuclear weapons.
Neutron halo
A neutron halo is an extended distribution of weakly bound neutrons around a nucleus's core, found near the neutron drip line and first seen in lithium-11.
Neutron imaging
Neutron imaging is a non-destructive technique that passes a neutron beam through an object to reveal internal structure and composition, complementing X-rays by detecting hydrogen, lithium, and isotopes.
Neutron initiator
A neutron initiator is a device that emits a burst of neutrons to start the fission chain reaction in a nuclear weapon, timed to when the core is most compressed.
Neutron interferometry
Neutron interferometry splits a beam of neutrons into coherent paths and recombines them, measuring phase shifts from gravity, magnetic fields, and nuclear interactions; first fringes were observed in 1974.
Neutron lifetime puzzle
The neutron lifetime puzzle is the long-standing, roughly 8.6-second discrepancy between beam experiments measuring the free neutron's lifetime near 888 seconds and bottle trap experiments near 878 seconds.
Neutron logging
Neutron logging is a borehole geophysical method that lowers a neutron source into a well and measures neutrons or gamma rays to estimate porosity, hydrogen content, and fluid saturation.