An investigator is monitoring the radioactive decay of a short-lived isotope using a Geiger-Müller (GM) tube and digital counter.
Name one natural source of background radiation.
Describe the experimental procedure the investigator must follow to measure and correct their subsequent experimental data for background radiation.
Before starting the main experiment, the investigator measures the background radiation inside the laboratory, recording a total of 120 counts over a period of 5 minutes. Calculate the average background count rate in counts per minute (cpm).
The investigator then places the radioactive sample near the GM tube and records the total count rate. At t=0 minutest = 0\text{ minutes}t=0 minutes, the total count rate is 344 cpm344\text{ cpm}344 cpm. At t=18 minutest = 18\text{ minutes}t=18 minutes, the total count rate is 64 cpm64\text{ cpm}64 cpm. Calculate the corrected count rate of the sample at both t=0 minutest = 0\text{ minutes}t=0 minutes and t=18 minutest = 18\text{ minutes}t=18 minutes.
Using your calculations from part (ii), determine the half-life of this isotope. Show your working clearly.
Iodine-123 is a gamma emitter with a half-life of approximately 13 hours and is widely used as a medical radioactive tracer to assess thyroid health. Explain why Iodine-123 is highly suitable for this diagnostic role. Refer to both its emission type and its half-life in your answer.