Beta Decay

In nuclear physics, beta decay is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted from an atom. Beta decay is a process which allows the atom to obtain the optimal ratio of protons and neutrons. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus (β−), while in the case of a positron emission as beta plus (β+). In electron emission, an electron antineutrino is also emitted, while positron emission is accompanied by an electron neutrino. Beta decay is mediated by the weak force.

Emitted beta particles have a continuous kinetic energy spectrum, ranging from 0 to the maximal available energy (Q), which depends on the parent and daughter nuclear states that participate in the decay. The continuous energy spectra of beta particle occurs because Q is shared between beta particle and a neutrino. A typical Q is around 1 MeV, but it can range from a few keV to a few tens of MeV. Since the rest mass energy of the electron is 511 keV, the most energetic beta particles are ultrarelativistic, with speeds very close to the speed of light.

Sometimes electron capture decay is included as a type of beta decay (and is referred to as "inverse beta decay"), because the basic process, mediated by the weak force is the same. However, no beta particle is emitted, but only an electron neutrino. Instead of beta-plus emission, an inner atomic electron is captured by a proton in the nucleus. This type of decay is therefore analogous to positron emission (and also happens, as an alternative decay route, in all positron-emitters). However, the route of electron capture is the only type of decay that is allowed in proton-rich nuclides that do not have sufficient energy to emit a positron (and neutrino). These may still reach a lower energy state, by the equivalent process of electron-capture and neutrino-emission.

Read more about Beta Decay:  β− Decay, β+ Decay, Electron Capture (K-capture), Nuclear Transmutation, Double Beta Decay, Bound-state β- Decay, Forbidden Transitions, Beta Emission Spectrum

Other articles related to "beta, decays, beta decay, decay":

Bk - Synthesis and Extraction - Preparation of Isotopes
... n,γ) reaction or neutron fusion) followed by beta-decay Plutonium-239 is further irradiated by a source that has a high neutron flux, several times higher than a conventional nuclear reactor, such as the ... Instead, it transforms by beta-decay into 249Bk The thus-produced 249Bk has a long half-life of 330 days and thus can capture another neutron ... Instead decays to the californium isotope 250Cf Although 247Bk is the most stable isotope of berkelium, its production in nuclear reactors is very inefficient due ...
Cowan–Reines Neutrino Experiment - Background
... through the study of electron spectra from the nuclear beta decay, it became apparent that, in addition to an electron, another particle with very small mass and ... Assuming energy conservation, this is only possible if the beta decay is a three-body rather than a two-body decay the latter produces monochromatic peak rather than a continuous energy spectrum ...
... of 8.1 hours the longest-lived isotope existing in naturally occurring decay chains is 219At with a half-life of 56 seconds ... Alpha decay characteristics for sample astatine isotopes Mass number Mass excess Mass excess of daughter Average energy of alpha decay Half-life Probability ... (the state with the lowest possible internal energy), making the former likely to decay into the latter ...
Delayed Neutron
... a fission product daughter after beta decay), anytime from a few milliseconds to a few minutes after the fission event ... Many of these fission products then undergo radioactive decay (usually beta decay) and the resulting nuclides are left in an excited state ... These usually immediately undergo gamma decay but a small fraction of them are excited enough to be able to decay by emitting a neutron in addition ...
History - The Rate of Beta Decay May Vary
... The rate of beta decay for an isotope was believed to be constant, no matter the conditions. 2012 presented data that the rate of gamma radiation - the result of beta decay - did change over time ... of neutrinos coming from the sun was affecting the rate of beta decay ...

Famous quotes containing the word decay:

    The goal of every culture is to decay through over-civilization; the factors of decadence,—luxury, scepticism, weariness and superstition,—are constant. The civilization of one epoch becomes the manure of the next.
    Cyril Connolly (1903–1974)