Beta Decay

What is Radioactivity?

The spontaneous decay or breakdown of an atomic nucleus is known as Radioactive Decay. This decay in a nucleus causes release of energy and matter from the nucleus.

The most common forms of Radioactive decay are –

  1. Alpha Decay (Helium nucleus is emitted)
  2. Beta Decay (Electrons are emitted)
  3. Gamma Decay (High energy photons are emitted)

What happens in Beta Decay?

Beta decay is a type of radioactive decay in which a beta ray is emitted from an atomic nucleus. During a beta decay, the proton in the nucleus is transformed into an neutron and vice versa. If a proton is converted to neutron, it is known as β+ decay. Similarly, if a neutron is converted to a proton, it is known as β- decay. Due to the change in the nucleus, a beta particle is emitted. The beta particle is a high speed electron when it is a β- decay and a positron when it is a β+ decay.

Beta Decay Example

One of the examples of beta decay is the β- decay of carbon atom.

Beta Decay of Carbon Atom

Here, a neutron of carbon is converted into proton and the emitted beta particle is an electron.

Similarly, the β+ decay of carbon-10 can be represented by an equation as follows:

Beta Decay of Carbon Atom

Here, the proton of the carbon atom is converted into neutron and the emitted beta particle is a positron.

Types of Beta Decay

There are three different types-

  1. Electron emission
  2. Electron capture
  3. Positron emission

Electron Emission – The process of ejection or emission of electron from the nucleus is known as electron emission. After the emission, the charge of nucleus increases by one.

Electron Capture – Electron capture is the phenomena where the nuclei decays by capturing one of the electrons that surround the nucleus. This leads to the decrease of one in charge of the nucleus.

Positron Emission – It is a third form of beta decay. A positron is a antimatter equivalent of an electron & has the same mass as of an electron, but bares the opposite charge of an electron. Positron decay produces a daughter nuclide with one less positive charge on the nucleus than the parent.

Fermi’s Theory

Fermi’s theory of beta decay or Fermi’s interaction is an illustration of beta decay by Enrico Fermi in 1933.  Enrico Fermi created the world’s first nuclear reactor.

He proposed that four fermions directly interacting with one another, at one vertex. This interaction explains beta decay of a neutron by direct coupling of a neutron with an electron, a neutrino (later determined to be an antineutrino) and a proton.

Stay tuned to BYJU’S to learn more about radioactivity and other physics concepts.


Practise This Question

Calculate the velocity of the centre of mass of the system of particles shown in figure.