Alpha, beta and gamma sim
Alpha particles are big and heavily charged: they ionise strongly and are stopped by a sheet of paper, or a few centimetres of air.
Alpha, beta and gamma · covers the GCSE, IGCSE, O-Level topic
What the sim shows
Alpha particles are big and heavily charged: they ionise strongly and are stopped by a sheet of paper, or a few centimetres of air. Beta particles (fast electrons) pass through paper but are stopped by a few millimetres of aluminium. Gamma rays pass through paper and aluminium almost untouched; thick lead only reduces them, here halving them for every 1 cm. The counter always picks up some background radiation (0.5 counts a second here), so a reading near that means nothing is getting through. Radioactive decay is random, so the counts go up and down; the bars show the average rate expected. The radiation spreads out, so twice as far away gives a quarter of the rate.
- The counter's light flashes on each count
- Below: expected rate for each absorber
Use it in your lessons
- Try it here: anyone can unlock 2 figures free, and a free account unlocks up to 5. Runs on a laptop, a Chromebook or a phone; nothing to install.
- Present it and share student links with the teacher plan, from US$5 a month, billed yearly.
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