Resources | Subject Notes | Physics
This section explores the spontaneous and random nature of nuclear emission. Radioactive decay is a probabilistic process, meaning we cannot predict when a specific nucleus will decay. However, we can describe the decay as happening randomly in direction.
Nuclear decay occurs spontaneously, without any external influence. This means that each individual nucleus has a certain probability of decaying within a given time period. This probability is characteristic of the specific radioactive isotope.
The direction in which a emitted particle travels is also random. We cannot predict the trajectory of a single emitted particle. However, if we observe a large number of decays, the distribution of the emitted particles will show a specific pattern, which is determined by the type of decay.
The three main types of nuclear emission – alpha, beta, and gamma – have distinct characteristics and patterns of emission.
| Emission Type | Particle Emitted | Charge | Mass | Direction |
|---|---|---|---|---|
| Alpha Decay | Helium Nucleus ($^{4}_{2}He$) | $ +2$ | Large | Generally follows a relatively straight path. Affected by the electric and magnetic fields, but less so than beta particles. |
| Beta Decay | Electron ($^{0}_{-1}e^−$) or Positron ($^{0}_{1}e^+$) | $-1$ (for electron) or $+1$ (for positron) | Very small | Follows a curved path due to the weak electromagnetic force. More significantly affected by electric and magnetic fields than alpha particles. |
| Gamma Decay | Gamma Ray ($γ$) | 0 | No mass | Travels in all directions. Not affected by electric or magnetic fields. |
The random direction of emission is crucial for understanding how radioactive materials spread and how detectors are designed to measure radiation.
The rate of radioactive decay is described by the half-life of a radioactive isotope. The half-life is the time it takes for half of the radioactive nuclei in a sample to decay. This is a constant value for a given isotope and is independent of external factors.
The spontaneous and random nature of decay means that even within a small time interval, the number of decays in a sample can vary significantly. However, over a large number of nuclei, the decay rate will be relatively constant.