A helium nucleus emitted by some radioactive substances, originally regarded as a ray.
- ‘A beta particle is an electron that could make it just a little way into the skin, while an alpha particle is a charged helium nucleus that will bounce right off of you.’
- ‘Scientists from a government-funded medical research laboratory at Harwell in Oxfordshire have produced the first direct proof that a single alpha particle emitted by uranium can damage human cells.’
- ‘The alpha particle is emitted by certain radioactive elements as they decay to a stable element.’
- ‘Because the alpha particle (the helium nucleus) with two protons and two neutrons is especially cohesive, the release of nuclear material is often in this form.’
- ‘The neutron is a better hammer than the alpha particle for smashing nuclei.’
We take a look at several popular, though confusing, punctuation marks.