Radioactivity

• Ionising radiation is given off during the decay of unstable isotopes
• Gamma radiation occurs for the loss of energy in an unstable nucleus
• How do Geiger muller tubes work?

  When alpha, beta or gamma radiation enters the tube it produces ions in the gas. The ions created in the gas enable the tube to conduct. A current is produced in the tube for a short time. The current produces a voltage pulse. Each voltage pulse corresponds to one ionising radiation entering the GM tube. The voltage pulse is amplified and counted.

  In short they measure the count rate as the amount of voltage pulses.
• Radio therapy and medical tracers -> gamma is able to pass out of patient 2 camera, it must have a long enough half life for observation period but not till excess irradiation, no toxid/decay into toxic/radioactive isotope: examples include an isotope of iodine and an technetium-99
• Automatic thickness monitoring uses beta radiation with a long half life.
• Smoke detectors basically the radiation ionises air gap to conduct electricity but the smoke prevents the radiation from doing such and so electric current decreases which is how it detects smoke.
• Smoke detectors use alpha radiation