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Half-life (symbol t½) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable atoms survive. The term is also used more generally to characterize any type of exponential (or, rarely ...
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 radioactive decay constant, the probability that an atom will decay per year, is the solid foundation of the common measurement of radioactivity. The accuracy and precision of the determination of an age (and a nuclide's half-life) depends on the accuracy and precision of the decay constant measurement. [9]
Zircon, a common target for Lu–Hf analysis. Lutetium–hafnium dating is a geochronological dating method utilizing the radioactive decay system of lutetium –176 to hafnium –176. [1] With a commonly accepted half-life of 37.1 billion years, [1][2] the long-living Lu–Hf decay pair survives through geological time scales, thus is useful ...
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 ...
Isochron dating. An isochron plot of the radiogenic daughter isotope (D*) against the parent isotope (P), all normalized to a stable isotope of the daughter element (D ref). It demonstrates the isotopic evolution as the sample ages from t 0 to t 1 to t 2. Isochron dating is a common technique of radiometric dating and is applied to date certain ...
The radioactive system behind hafnium–tungsten dating is a two-stage decay as follows: 182 72 Hf → 182 73 Ta e − ν e 182 73 Ta → 182 74 W e − ν e. The first decay has a half-life of 8.9 million years, while the second has a half-life of only 114 days, [7] such that the intermediate nuclide tantalum-182 (182 Ta) can effectively be ignored.
The age of a sample is given by the age equation: = (+) where λ is the radioactive decay constant of 40 K (approximately 5.5 x 10 −10 year −1, corresponding to a half-life of approximately 1.25 billion years), J is the J-factor (parameter associated with the irradiation process), and R is the 40 Ar*/ 39 Ar ratio.