A fast neutron is a free neutron with a kinetic energy level close to 1 MeV (10 TJ/kg, hence a speed of 14,000 km/s. They are named fastneutrons to distinguish them from lower-energy thermal neutrons, and high energy neutrons produced in cosmic showers. Fast neutrons are produced by nuclear processes such as nuclear fission. A free neutron is a neutron that exists outside of a nucleus. ... Kinetic energy (also called vis viva, or living force) is energy possessed by a body by virtue of its motion. ... An electronvolt (symbol: eV) is the amount of energy gained by a single unbound electron when it falls through an electrostatic potential difference of one volt. ... Properties In physics, the neutron is a subatomic particle with no net electric charge and a mass of 939. ... A thermal neutron is a free neutron with a kinetic energy level of ca. ... Sketch of induced nuclear fission, a neutron (n) strikes a uranium nucleus which splits into similar products (F. P.), and releases more neutrons to continue the process, and energy in the form of gamma and other radiation. ...
Fast neutrons can be made into thermal neutrons via a process called moderation. This is done with a neutron moderator. In reactors, typically heavy water, light water, or graphite are used to moderate neutrons. In nuclear engineering, a neutron moderator is a medium which reduces the velocity of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a chain reaction. ... Heavy water is dideuterium oxide, or D2O or 2H2O. It is chemically the same as normal water, H2O, but the hydrogen atoms are of the heavy isotope deuterium, in which the nucleus contains a neutron in addition to the proton found in the nucleus of any hydrogen atom. ... In speaking of nuclear reactors, light water is ordinary water. ... Graphite (named by Abraham Gottlob Werner in 1789, from the Greek γραφειν: to draw/write, for its use in pencils) is one of the allotropes of carbon. ...
Fastneutron radiography is a non-destructive testing method with a variety of industrial applications and the potential for element sensitive imaging for contraband and explosives detection.
The limitations imposed by the source and the physics of the interaction of neutrons with the detector and the radiography specimen are central to the development of new detectors with the potential to improve the detectability of small features in resonance fastneutron radiography applications.
The problem facing fastneutron radiographers is developing position sensitive neutron detection methods that have a high efficiency, in other words, detect as many neutrons as possible, whilst minimising: resolution loss, the detection of low energy scattered neutrons and the detection of undesirable radiation in the background produced by the accelerator-based source.
Feeds |
Contact