Radiation, ionizing from nuclear decay

Of the various ionizing particulate radiations, the most important in terms of likelihood for human exposure are alpha particles, beta particles, protons, and neutrons. Alpha and beta particles occur as a result of the radioactive decay of unstable atoms. Neutrons generally result from nuclear reactions, such as nuclear fission (as in nuclear reactors and fission-based nuclear weapons) and charged-particle activation of target atoms (as with some accelerator-produced... 

Building blocks, isotopes, nuclear reactions (particularly neutron induced), neutron sources, radioactive decay, calculation of radiation level from radioisotope ionization of gases, and ionization in neutron detectors by secondary actions. 

The process of radioactive decay (also known as radioactivity) involves the ejection from a nucleus of one or more nuclear particles and ionizing radiation. Nuclear fission is a reaction in which the nucleus splits into smaller nuclei, with the simultaneous release of energy. Most radioisotopes undergo radioactive decay processes and are converted into different smaller atoms. 

Radioactive waste from certain nuclear power plants and from weapons testing can lead to health problems. For example, ions of the radioactive isotope strontium-90, an alkali metal, exhibit chemical behaviour similar to calcium ions. This leads to incorporation of the ions in bone tissue, sending ionizing radiation into bone marrow, and possibly causing leukemia. Given the following equation for the decay of strontium-90, how would you complete it ... 

The mode of radioactive decay is dependent upon the particular nuclide involved. We have seen in Ch. 1 that radioactive decay can be characterized by a-, jS-, and y-radiation. Alpha-decay is the emission of helium nuclei. Beta-decay is the creation and emission of either electrons or positrons, or the process of electron capture. Gamma-decay is the emission of electromagnetic radiation where the transition occurs between energy levels of the same nucleus. An additional mode of radioactive decay is that of internal conversion in which a nucleus loses its energy by interaction of the nuclear field with that of the orbital electrons, causing ionization of an electron instead of y-ray emission. A mode of radioactive decay which is observed only in the heaviest nuclei is that of spontaneous fission in which the nucleus dissociates spontaneously into two roughly equal parts. This fission is accompanied by the emission of electromagnetic radiation and of neutrons. In the last decade also some unusual decay modes have been observed for nuclides very far from the stability line, namely neutron emission and proton emission. A few very rare decay modes like C-emission have also been observed. 

Several actinide nuclides have found other applications. Heat sources made from kilogram amounts of Pu have been used to drive thermoelectric power units in space vehicles. In medicine, Pu was applied as a long-lived compact power unit to provide energy for cardiac pacemakers and artificial organs. Am has been used in neutron sources of various sizes on the basis of the (a,n) reaction on beryllium. The monoenergetic 59-keV y radiation of Am is used in a multitude of density and thickness determinations and in ionization smoke detectors. Cf decays by both a emission and spontaneous fission. One gram of Cf emits 2.4 10 neutrons per second. "Cf thus provides an intense and compact neutron source. Neutron sources based on Cf are applied in nuclear reactor start-up operations and in neutron activation analysis. 

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