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Alpha decay or α-decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus). The parent nucleus transforms or "decays" into a daughter product , with a mass number that is reduced by four and an atomic number that is reduced by two.
Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. [5] They are generally produced in the process of alpha decay but may also be produced in different ways. Alpha particles are named after the first letter in the Greek alphabet, α.
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.
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.
Ernest Rutherford, working in Canada and England, showed that radioactive decay can be described by a simple equation (a linear first degree derivative equation, now called first order kinetics), implying that a given radioactive substance has a characteristic "half-life" (the time taken for the amount of radioactivity present in a source to ...
Gamow discovered a theoretical explanation of alpha decay by quantum tunneling, invented the liquid drop model - the first mathematical model of the atomic nucleus, worked on radioactive decay, star formation, stellar nucleosynthesis, Big Bang nucleosynthesis (which he collectively called nucleocosmogenesis), predicted the existence of the ...
The decay-chain of uranium-238, which contains radium-226 as an intermediate decay product. 226 Ra occurs in the decay chain of uranium-238 (238 U), which is the most common naturally occurring isotope of uranium. It undergoes alpha decay to radon-222, which is also radioactive; the decay chain ultimately terminates at lead-206.
The decay energy is the mass difference Δm between the parent and the daughter atom and particles. It is equal to the energy of radiation E . If A is the radioactive activity , i.e. the number of transforming atoms per time, M the molar mass, then the radiation power P is: