Beta Decay

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Beta Decay

This lesson aligns with NGSS PS1.C

Introduction

Beta Decay represents a form of radioactive decay wherein a proton undergoes a transformation into a neutron, or vice versa, within the nucleus of the radioactive specimen. This process, along with others such as alpha decay, facilitates the adjustment of the nucleus of the radioactive specimen towards achieving an optimal neutron/proton ratio. During this transformation, the nucleus emits a beta particle, which can manifest as either an electron or a positron. In this article, we will learn about beta decay, what happens in beta decay and types of beta decay.

Understanding Beta Decay

Beta decay constitutes a form of radioactive nuclear decay characterized by the release of a beta particle, either a fast-energetic electron or positron, from an atomic nucleus. This emission leads to the conversion of the initial nuclide into an isobar of that nuclide.

For instance, in the beta decay of a neutron, it transforms into a proton by emitting an electron along with the anti-neutrino. Conversely, a proton can convert into a neutron through positron emission, where it emits a positron along with a neutron.

It is noteworthy that neither the beta particle nor its associated anti-neutrino exists within the nucleus prior to beta decay; instead, they are generated as part of the decay process. This transformative process aids unstable atoms in attaining a more stable ratio of protons to neutrons.

Nuclear Binding Energy:

The nuclear energy binding of a nuclide, influenced by beta decay and other decay forms, determines the occurrence of its decay. The binding energies of all identified nuclides collectively form the nuclear band or the stabilization valley. For the electron or positron emission to be energetically viable, the energy release must be positive.

Types of Beta Decay:

Beta-Minus Decay (β-):

In this type, a neutron is transformed into a proton within the nucleus, releasing a beta-minus particle (an electron) and an antineutrino. The atomic number increases by one while the mass number remains unchanged.

The antineutrino is the antimatter counterpart of the neutrino. Both of these entities are neutral particles characterized by negligible mass. They exhibit weak interactions with matter, to the extent that they can traverse the entire Earth without undergoing any significant disturbance.
In this decay, the change in atomic configuration is:

Instances of beta-minus decay include the transformation of C-14 into N-14, a phenomenon typically observed in neutron rich nuclei.

Potassium-40 (β- Decay):

Potassium-40 undergoes beta-minus decay, converting a potassium nucleus into a calcium nucleus. This isotope is vital in geological dating techniques and is present in potassium-rich minerals.

Beta-Plus Decay (β+):

A proton in the nucleus is converted into a neutron, emitting a beta-plus particle (a positron) and a neutrino.

This process decreases the atomic number by one while maintaining the mass number.
A positron is the antimatter counterpart of an electron, sharing identical characteristics except for its positive charge.
A neutrino shows the same behavior as the antineutrinos. As expressed in the equation, it is:

Beta-plus decay occurs only when the daughter nucleus proves to be more stable than the mother nucleus. This distinction results in the conversion of a proton into a neutron, along with the emission of a positron and a neutrino. Importantly, there is no increase in the mass number as both a proton and a neutron possess equivalent masses.

Positron Emission Tomography (PET) Tracers (β+ Decay):

Isotopes like fluorine-18 undergo beta-plus decay, emitting positrons. These positrons annihilate with electrons, producing gamma rays. This process is utilized in medical imaging techniques like positron emission tomography (PET).

Fermi’s Theory of Beta Decay

Fermi's theory of beta decay, also known as Fermi's interaction, was introduced by Enrico Fermi in 1933. Notably, Enrico Fermi played a pivotal role in constructing the world's first nuclear reactor.

According to Fermi's theory, beta decay is elucidated through the direct interaction of four fermions at a single vertex. This framework describes beta decay as the direct coupling of a neutron with an electron, a neutrino (later identified as an antineutrino), and a proton.

Summary

Beta decay constitutes a form of radioactive nuclear decay characterized by the release of a beta particle, either a fast-energetic electron or positron, from an atomic nucleus.
In a beta minus decay, a neutron is transformed into a proton, releasing a beta-minus particle (an electron) and an antineutrino.
In Beta minus Decay, the atomic number increases by one while the mass number remains unchanged.
A proton in the nucleus is converted into a neutron, emitting a beta-plus particle (a positron) and a neutrino.
This process decreases the atomic number by one while maintaining the mass number.

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