Beta Decay: Definition, Examples, Types and Fermi’s Theory

Beta decay can be referred to as one of the types of reactions that take place during the nuclear reactions. In beta decay, a neutron decomposes into an electron and a proton. The process of radioactivity is very useful but it is a dangerous phenomenon.

Keyterms: Radioactivity, Ci or curie, Bq (Becquerel), Alpha Decay, Beta Decay, Gamma Deca, Beta minus decay, Beta plus decay, Neutron, Proton, Electron

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Beta Decay Definition

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In radioactivity, beta decay is a process in which a proton is transformed into a neutron or vice versa. This reaction takes place inside the nucleus of a radioactive sample. Both the alpha decay & beta decay let the nucleus get as possible of the optimum proton or neutron. While this, a beta particle is emitted by the nucleus that can either be a positron or an electron. What we need to remember is that the positron generated basically to obey the law of conservation of charge. The proton may turn to a neutron or vice-versa. Beta-decay is a process that occurs via weak interaction. It is of two types – Beta minus decay (\(\beta\)-) and beta plus decay(\(\beta\)+).

Beta Decay

In short beta decay can be elaborated as a property of various elements which are naturally available along with their isotopes to produce artificial isotopes of those elements.

There are three ways for differentiating this phenomenon which are- neutron decay, proton decay and electron decay. In every decay, the atomic number keeps on changing continuously for the formation of parents atoms & daughters atoms are formed of different elements.

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Beta Decay Procedure

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In the process of Beta decay, the proton present inside the nucleus turns into a neutron or the exact opposite thing takes place. If a neutron gets converted to proton, the process is called (\(\beta\)-) decay and if the proton is converted to neutron, it is known as (\(\beta\)+) decay. Beta particles are emitted due to the change in the nucleus. And these particles are used to cure various health conditions like –bone cancer, eye cancer. Beta particles are often used as tracers

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Example of Beta Decay

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(\(\beta\)-) Decay is an example of Beta decay of carbon atoms. The neutron of a carbon atom is converted into proton and emits beta particle which is an electron. An example of (\(\beta\)-) decay of C-14 into Nitrogen-14:

¹⁴₆C → ¹⁴₇N + e^- + v_e

This form of decay is also known as nuclear transmutation. The decaying element is known as parent nuclide and the resulting element is called daughter nuclide.

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Beta Decay Types

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The radioactivity beta decay involves two types-

Radioactivity beta decay Types

1. Beta- Minus Decay

- In Beta Minus decay a proton is transformed which causes an increase in the atomic number of the atom.

- During the process, the nucleus also produces an electron & an antineutrino to balance the conservation of charge.

- The antimatter counterpart of neutrinos is known as antineutrino. These are neutral particles with very negligible mass. The interactions of these particles with other matter are so weak that the entire earth remains undisturbed.

- The atomic configuration in beta-minus decay is:

^A_ZX → A_Z+1 Y +e^- +v

N = P + e^- + v^-

2. Beta- Plus Decay

Beta plus decay

- Beta plus decay results in the transformation of a proton into a neutron and that decreases the atomic number of the radioactive element. Hence, a loss of proton and gain of a neutron is experienced inside the nucleus.

- The beta decay process too produces a positron & a neutrino to maintain the law of conservation of charges. The Positron consists of a positive charge.

- The behaviour of neutrino is similar to that of the antineutrinos.

- The equation of its atomic configuration is:

^A_ZX → ^A_Z-1Y + e⁺ + v

P = N+ e⁺ + v

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Beta Decay: Beta Emission

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The beta particles which are emitted by some radioactive nuclei consist of high energy & high speed electrons like for potassium – 40. The penetrations of the beta particles are greater than the alpha particles but still there is a lack of strength to the beta-gamma rays. The beta particles which are emitted are in the ionizing radiation form and also known as beta emission or beta rays.

Beta Decay: Fermi’s Theory

According to Enrico Fermi’s proposed theory, the 4 fermions interact directly with one another at one vertex. This type of interaction takes place by coupling an electron with a neutron, a neutrino and also a proton. This theory was formulated by Fermi in 1933.

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Things to Remember

• Beta Decay is a part of CBSE class 12 physics syllabus and is taken from chapter 13, Nuclei. 
• It carries 1 to 2 marks and the overall chapter carries 4-5 marks in CBSE Class 12 examinations.
• Radioactive atoms consist of energy and it also produces electromagnetic waves, the type of emission is called radiation.
• Half-life is known as the rate of radioactive element decays, i.e. the total time needed for one half of a given quantity of isotope.
• Beta decay of elements is generally the production of artificial isotopes of the elements.
• There are two types of beta decay- Beta plus & beta minus.