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?

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.

Practise This Question

A cart of mass 'M' is at rest on a frictionless horizontal surface and a pendulum bob of mass 'm' hangs from the roof of the cart. The string breaks, the bob falls on the floor, makes several collisions on the floor and finally lands up in a small slot made on the floor. The horizontal distance between the string and the slot is 'L'. Find the displacement of the cart during this process.