Half-Life

The term half-life refers to the time taken for half of the radioactive nuclei in a sample to decay.
Radioactive decay is a random process, meaning we cannot predict when a specific atom will decay.
However, each radioactive isotope has a specific half-life that is constant and does not change.
During each half-life, half of the remaining radioactive nuclei decay, regardless of the initial amount.
The half-life of a radioactive isotope can range from fractions of a second to thousands of years.

The count rate or activity of a radioactive source is the number of radioactive decays per second. It’s usually measured in becquerel (Bq).
The count rate decreases over time as the radioactive nuclei decay.
By plotting a graph of count rate against time, the half-life can be found by determining the time period for the count rate to halve.
The precise measurement of half-life requires careful experimentation and data analysis.

In medicine, radioisotopes with short half-lives are used for diagnostic procedures, such as PET scans, as they decay quickly and minimise the patient’s exposure to radiation.
Radioisotopes with longer half-lives are used in radiotherapy for treating cancers, as they emit radiation over a longer period of time.
Understanding half-life is crucial in nuclear waste management, as it helps to decide the appropriate storage and containment measures. Radioactive materials with long half-lives pose a risk for an extended period and need to be securely safely for thousands of years.

The concept of half-life can also help us understand the risks associated with radiation. A short half-life means the radiation will be intense but short-lived, while a long half-life means the radiation will be less intense but will last for a long period.
It’s important to choose appropriate precautions and protection based on the half-life and type of radiation when working with radioactive sources.