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Interaction of Radiation with Matter
Published in William H. Hallenbeck, Radiation Protection, 2020
High-energy electron accelerators (betatrons or synchrotrons) produce high energy photons. These high energy photons can be absorbed by a nucleus and cause the ejection of a neutron, proton, or alpha. Also, nuclear fission can be induced in heavy nuclei. Such nuclear interactions are referred to as photonuclear reactions or photodisintegration. Daughter nuclei are often radioactive. The probability of a photonuclear interaction is orders of magnitude smaller than the combined probabilities of the other three types of photon interactions with matter.
Instrumentation, Particle Accelerators, and Particle and Radiation Detection
Published in Zeev B. Alfassi, Max Peisach, Elemental Analysis by Particle Accelerators, 2020
Trends of neutron yield as a function of bombarding energy show a continuing exponential rise in output. At energies well above the Coulomb barrier, the total neutron yield from thick targets bombarded with deuterons rises with the 3/2 power of the energy. The photodisintegration (with X-ray photons) or the electrodisintegration (with electrons) of a nucleus usually involves the emission of a neutron as the disintegration product. It can be assumed that only photodisintegration takes place by means of the (γ, n) reaction, and that electrodisintegration is the result of X-ray production by the bombarding electron and consequent (γ, n) effect. The (γ, n) reactions are divided into two groups:
Nucleosynthesis, Cosmic Radiation, and the Universe
Published in Ivan G. Draganić, Zorica D. Draganić, Jean-Pierre Adloff, Radiation and Radioactivity on Earth and Beyond, 2020
Ivan G. Draganić, Zorica D. Draganić, Jean-Pierre Adloff
The fusion of 28Si and the syntheses of heavier nuclei up to mass number 56 occur at temperatures above 109 degrees kelvin. The nuclei formed are in the region of iron and nickel in the periodic chart, and belong to the most stable existing nuclei. Their accumulation leads to a new scenario of nucleosynthesis in which photonuclear reactions become involved. Increasingly energetic photons are released in the core as the temperature rises, and these destroy the stable nuclei. Photodisintegration generates neutrons which promote further nucleosynthesis.
Beta-Ray-Bremsstrahlung Contributions to Short-Lived Delayed Photoneutron Groups in Heavy Water Reactors
Published in Nuclear Science and Engineering, 2023
Yanuar Ady Setiawan, Hemantika Sengar, Douglas A. Fynan, Arief Rahman Hakim
Hard gamma rays emitted during the isomeric transition of the excited daughters of fission-product decay can induce photodisintegration of 2H (D) or 9Be owing to the low neutron separation energies of these nuclei. Delayed photoneutrons (PNs) contribute up to a few percent of the effective delayed neutron fraction in heavy water reactors (HWRs), and the much longer half-lives of some PN precursors relative to the longest-lived direct-delayed neutron precursor (87Br with 55.9-s T1/2) make PNs important to the kinetic response of HWRs. Despite over 120 power, production, research, and zero-power HWRs having been operated in at least 26 countries during the past 75 years, no consistent set of PN group constants has been established, and the group constants in use appear to be patched together from a handful of legacy experiments1–5 using different fissile isotopes, fuel materials and geometries, and lattices. PN production and derived group data are strongly dependent on gamma-ray transport and attenuation in the specific fuel/lattice geometry. Only recently has microscopic isotopic analysis using nuclear data and nuclear physics models been initiated.6
A Preliminary Proposal for a Hybrid Lattice Confinement Fusion–Fission Reactor for Mobile Nuclear Power Plants
Published in Fusion Science and Technology, 2022
Luciano Ondir Freire, Delvonei Alves de Andrade
The thermal neutron supply system (TNSS) contains the innovative aspect of lattice confinement fusion. It receives deuterium gas, charges it in a metal lattice, and uses the fast neutrons coming from the fuel to heat the deuterons that in turn may undergo fusion reactions. The process of heating deuterons thermalizes fast neutrons, making them adequate for fission reactions in the fuel. The fusion reactions also produce more neutrons, boosting the reactivity of the reactor. Additionally, energetic gamma rays from the fuel may also generate neutrons by photodisintegration, further enhancing reactor reactivity.