4th Week: Decays, Tunneling and Cross Sections C

Radioactive Decay

The nucleus of an atom is made up of protons (Z) and neutrons (N). The total number of protons and neutrons is $Z+N=A$ In nature, an atom undergoes Radioactive Decay when the number of protons and/or neutrons in the nucleus changes. There are three main processes by which these changes can occur. These mechanisms are Alpha, Beta, and Gamma Decay.

Alpha Decay

An alpha particle is just another name for a ${^{4}He}$ atom. an atom, $(Z,A)$, can be said to undergo alpha decay if the nucleus of the atom loses two neutrons and two protons, ejecting an alpha particle as shown here:

$\left(Z,A\right)->\left(Z-2,A-4\right)+{^{4}He}$ As a simple example, the equation for a Lithium atom undergoing alpha radiation would be as follows:

$\left(3,7\right)->\left(1,3\right)+{^{4}He}$