Negatrons emission

This is a process characteristic of nucleides with high n p ratios, and involving the loss of an electron from the nucleus, which is usually, but not invariably accompanied by the emission of y-photons. A detailed energy balance reveals that the simple picture cannot account for all the energy lost by the nucleus in the decay and the emission of an additional particle - the antineutrino, v is postulated to account for this. The general equation for a negatron emission is... 

BETA DECAY. The process that occurs when beta particles are emitted by radioactive nuclei. The name beta particle or beta radiation was applied in the early years of radioactivity investigations, before it was fully understood what beta particles are. It is known now, of course, that beta particles are electrons. When a radioactive nuclide undergoes beta decay its atomic number Z changes by +1 or —1, but its mass number A is unchanged. When the atomic number is increased by 1, negative beta particle (negatron) emission occurs and when the atomic number is decreased by 1, there is positive beta particle (position) emission or orbital electron capture. 

The term antineutrino usually denotes an antiparticle whose emission is postulated to accompany radioactive decay by negatron emission, such as, for example, in neutron decay into a proton p+, negatron e and aiiliiieulnno IT, expressed by the equatiuii n p+ + e + vj. Capture of a neutrino by the neutron, ve + n - p+ + e would be an equally good description of the process. Positron emission is accompanied by a neutrino,... 

In die past the terms neutrino and antineutrino were sometimes used in reverse sense to diat stated above, i.e., the neutrino is said to accompany negatron emission and die antineutnno. positron emission. The preferred usage has been accepted in order to provide conservation of leptons in the... 

Fig. 1, The cncigy regions for wliich negatron emission, positron emission, and orbital eleclron capture are energetically possible...

Nuclear chemists consIcJer (3 ctecay to be a more general process that Includes three decay modes negatron emission (which the text calls S decay ), positron emission, and electron capture. 

If a nucleus has a NIZ ratio too high for stability, it is said to be neutron-rich. It will undergo radioactive decay in such a manner that the neutron to proton ratio decreases to approach more closely the stable value. In such a case the nucleus must decrease the value of N and increase the value of Z, which can be done by conversion of a neutron to a proton. When such a conversion occurs within a nucleus, 8 (or negatron) emission is the consequence, with creation and emission of a negative /3-particle designated by 8 or e (together with an anti-neutrino, here omitted for simplicity, see Ch. 4). For example ... 

Each mode of decay in branching may be treated separately the decay in an individual branch has a half-life based on the partial decay constant. Since only the total decay constant (the rate with which the mother nuclide, 2X in (4.50), decays) is observable directly, partial decay constants are obtained by multiplying the observed total decay constant by the fraction of parent decay corresponding to that branch. Cu decays 43 % by electron capture, 38% by negatron emission, and 19% by positron emission. The observed total decay constant is equal to 0.0541 h based on the half-life of 12.8 h. The partial constants are ... 

The various decay processes are listed in Table 1. Radioactive nuclides emit either nucleons (alpha particles, very rarely protons or neutrons) or electrons (negatrons, positrons). As an alternative to the emission of a positron, a proton may capture an electron of the K-shell (K-capture). By the emission of an alpha particle the mass number and the atomic number are reduced by the emission of electrons either the number of neutrons (jS -decay, negatron emission) or the number of protons ()S -decay, positron emission) is reduced. By K-capture also the number of protons is reduced. Due to the missing electron in the K-shell, characteristic X-rays of the newly produced atomic species are emitted. 

Negatron emission. In this case a neutron is converted to a proton resulting in the ejection of a negatively charged beta (P) particle known as a negatron (P-ve). 

Any radioactive decay process in which the atomic number Z changes but the mass number A does not is classified as fi decay. Three types of p decay are encountered negatron emission, positron emission, and electron capture. Examples of the three processes are the following ... 

P decay (or negatron emission) occurs through the ejection of a p particle from the nucleus. This change does not involve expulsion of a p particle that was in the nucleus rather, a neutron is converted into a proton, which remains in the nucleus, and a /3 particle, which is expelled immediately ... 

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