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Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is considered radioactive. Three of the most common types of decay are alpha, beta, and gamma decay.
The incoming gamma ray effectively knocks one or more neutrons, protons, or an alpha particle out of the nucleus. [1] The reactions are called (γ,n), (γ,p), and (γ,α). Photodisintegration is endothermic (energy absorbing) for atomic nuclei lighter than iron and sometimes exothermic (energy releasing) for atomic nuclei heavier than iron.
In general (depending on the half-life of the decay), gamma rays have very narrow linewidths. This means they are very sensitive to small changes in the energies of nuclear transitions. In fact, gamma rays can be used as a probe to observe the effects of interactions between a nucleus and its electrons and those of its neighbors.
Its gamma decay mode can be easily detected by a camera, allowing the use of smaller quantities. And because technetium-99m has a short half-life, its quick decay into the far less radioactive technetium-99 results in relatively low total radiation dose to the patient per unit of initial activity after administration, as compared with other ...
Delayed gamma emissions are the most common form of delayed radiation, but are not the only form. It is common for the short-lived isotopes to have delayed emissions of various particles. In these cases, it is commonly called a beta-delayed emission. This is because the decay is delayed until a beta decay takes place.
Iodine-123 (123 I) is a radioactive isotope of iodine used in nuclear medicine imaging, including single-photon emission computed tomography (SPECT) or SPECT/CT exams. The isotope's half-life is 13.2232 hours; [1] the decay by electron capture to tellurium-123 emits gamma radiation with a predominant energy of 159 keV (this is the gamma primarily used for imaging).
The decay scheme of a radioactive substance is a graphical presentation of all the transitions occurring in a decay, and of their relationships. Examples are shown below. It is useful to think of the decay scheme as placed in a coordinate system, where the vertical axis is energy, increasing from bottom to top, and the horizontal axis is the proton number, increasing from left to right.
Types of radioactive decay include gamma ray; beta decay (decay energy is divided between the emitted electron and the neutrino which is emitted at the same time) alpha decay; The decay energy is the mass difference Δm between the parent and the daughter atom and particles.