the use of a radioactive isotope depends on:
- its half-life
- the type of radiation it gives out
1) Automatic thickness monitoring- used in the production of metal foil
- the radioactive source emits beta radiation.
- the amount of radiation passing through the foil depends on the thickness of the foil.
- and there is a detector on the other side to measure this as:
- if the thickness of the foil is too much- the detector reading stops because there is no beta particles flowing through- and so detector sends a signal to the rollers to increase pressure on the foil to make it thinner.
- if beta particles ARE passing through- it signals the detector for the rollers to loosen up to make it thicker.
Alpha would not be used here because it would be stopped by the material and so the detector would not be able to detect the radiation.
2) Radioactive tracers- used to trace the flow of a substance through a system: eg test if a patient's kidney is blocked.
- before test: patient drinks water containing a tiny amount of radiactive substance
- a detector is placed against each kidney.
- if normal/undamaged:
the water, including the radioactive substance would flow in and out a normal kidney= reading would go up and down.
- if not normal/damaged: