Radionuclide Production
Michael Ljungberg in Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
The most typical neutron reaction is the (n, γ) reaction in which a thermal neutron is captured by the target nucleus forming a compound nucleus. The decay energy is emitted as a prompt gamma ray. A typical example is the reaction 59Co (n, γ) 60Co that produces an important radionuclide used in external therapy. However, since the produced radionuclide is of the same element as the target the specific activity, that is, the radioactivity per mass of the sample, is low. This type of nuclear reaction has little interest when labelling radiopharmaceuticals. In light elements, other nuclear reactions resulting from thermal neutron irradiation are possible, like (n, p). Table 4.1 lists possible production reactions for some biologically important radionuclides
Dictionary
Mario P. Iturralde in Dictionary and Handbook of Nuclear Medicine and Clinical Imaging, 1990
Nuclear fission. The generation of nuclear power is based upon the fundamental process of nuclear fission. Physically the term is applied to a particular type of nuclear reaction in which a heavy nucleus is split into two nuclei of medium weight, called fission fragment, which are usually radioactive. Several neutrons and γ-rays are also emitted in the process. Some elements are known to undergo fission spontaneously, but the rates are usually very low and the process occurs much more readily when the material is bombarded with nuclear particles or γ-rays. From the practical point of view, however, fission induced by neutrons is the most important.
Overview of the Basic Concepts of Radiation Protection
Gaetano Licitra, Giovanni d'Amore, Mauro Magnoni in Physical Agents in the Environment and Workplace, 2018
Neutrons and gamma radiation, though, can also generate ‘nuclear reactions’, inducing effects in the nucleus of the atom itself. Nuclear reactions generated by neutrons include scattering of neutrons (either inelastic or elastic), capture of a neutron in the nucleus, stripping of one or more nucleons from the nucleus and nuclear fission, which is the induction of a large instability in the nucleus, eventually concluding with the breaking up of the nucleus into two smaller and more stable units and the emission of large quantities of energy in various forms.
Investigation of radiation protective features of azadispiro derivatives and their genotoxic potential with Ames/Salmonella test system
Published in International Journal of Radiation Biology, 2023
Burak Alaylar, Bünyamin Aygün, Kadir Turhan, Mehmet Karadayı, Esra Cinan, Zuhal Turgut, Gökçe Karadayı, Mohammed Ibrahim Abu Al-Sayyed, Medine Güllüce, Abdulhalik Karabulut
The neutron cross-section is aimed to search the probability of interactions that may occur between the neutron entering a target material and the core of the target material. These interactions usually include elastic and inelastic or nuclear reactions, such as neutron capture, fission, and spallation. Barn (10−28 m2 or 10−24 cm2), which is accepted as the standard unit, is used to indicate this cross-section of interaction. These cross-sections are mostly determined with total macroscopic cross-section and the removal cross-section value is found as follows. The large total or removal cross-section of this cross-section expresses the high probability of interaction that the neutron coming to the material can make with the nucleus of the material (El-Khayatt and El-Sayed Abdo 2009). Any interaction of neutrons with the target material can be defined in different cross-sections as below.
Radiological risk assessment of the Hunters Point Naval Shipyard (HPNS)
Published in Critical Reviews in Toxicology, 2022
Dennis J. Paustenbach, Robert D. Gibbons
Pu-239 has a radioactive half-life of 24,110 years and is produced when uranium absorbs a neutron. Small amounts of plutonium occur naturally, but large quantities have been produced in nuclear reactions or released from atmospheric nuclear weapons tests. Pu-239 transitions by alpha decay. Its decay products emit alpha, beta, and gamma radiation depending upon which radionuclide is being evaluated and can pose both an internal and external radiation hazard. Pu-239 is present in most soils in the United States at various concentrations (ICRP 2008; Johnson et al. 2012). The potential for Pu-239 to be present on ships returning from nuclear weapons tests in the Pacific and Pu-239 use in calibrating radiation detection equipment were primary reasons it was identified as an ROC at HPNS (USN 2004).
The statistical properties of the threshold model and the feedback leadership condition
Published in Journal of Applied Statistics, 2020
Alexandra M. Espinosa, Luís Horna
An important property of collective actions is the critical mass of participation, a concept adopted from the natural sciences [70]. In nuclear physics, the critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction. Similarly, in the social sciences, the critical mass is defined as the participation rate needed to make a collective action self-sustaining [70]. Apparently, the natural and the social sciences share the same concept of critical mass, but it is not actually correct. For instance, the number of neutrons needed to induce an atom to ‘participate’ in a nuclear reaction does not change from one atom to another. But, in the threshold model, the circumstances that persuade an individual to ‘react’ vary from individual to individual.
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