What is an Alpha Particle?

Michael Anissimov
Michael Anissimov

The alpha particle is a type of ionizing radiation. With its partners the gamma particles and beta particles, alpha particles are one of the most prevalent forms of radiation. Each particle is essentially a helium nucleus, which consists of two neutrons and two protons, without electrons, giving it a net positive charge. Due to their relatively high mass, these particles are the most destructive form of ionizing radiation, but the trade-off is that their penetration is low. A piece of paper stops alpha particles, whereas the lighter beta particles require a aluminum barrier.

Tobacco leaves contain small amounts of polonium, which emits alpha particles.
Tobacco leaves contain small amounts of polonium, which emits alpha particles.

Alpha particles are emitted from various radioactive substances. Unlike beta decay, alpha decay is mediated by the strong force. According to classical Newtonian laws, the attraction of the nucleus should be too strong to let alpha particles leave it under any circumstances. However, quantum tunneling permits it anyway. Quantum tunneling is the instantaneous teleporting of the particle to a place outside the nucleus.

Americium, which is found in smoke detectors, is an alpha emitter.
Americium, which is found in smoke detectors, is an alpha emitter.

Because alpha particles have such low penetrating force, they are stopped by human skin, presenting little danger unless the source is swallowed. This was the sad fate of Russian ex-spy Alexander Litvinenko, thought to be the first person to die from acute radiation poisoning as a result of ingesting the alpha emitter polonium. Other known alpha emitters include americium (found in smoke detectors), radium, radon gas, and uranium. When coupled together with certain other radioactive substances, alpha emitters can agitate neutron emitters to release the neutrons. Neutron emission is a critical part of nuclear reactor and nuclear weapons design.

It it theorized that tobacco leaves that contain small amounts of polonium could be responsible for lung cancer among smokers.
It it theorized that tobacco leaves that contain small amounts of polonium could be responsible for lung cancer among smokers.

In investigations into the health effects of smoking, it was found that tobacco leaves contain small amounts of polonium, which emits alpha particles. It is theorized that this could be partially responsible for lung cancer among smokers. In evolution, alpha emitters play a critical role — their likelihood of causing a chromosomal mutation is over 100 times greater than with other types of radiation. Most of the time, this produces less-fit mutants, but when combined with selection over thousands or millions of years results in adaptive biological designs.

Some types of ionizing radiation can cause serious health issues, so it important for people to be aware of possible exposure.
Some types of ionizing radiation can cause serious health issues, so it important for people to be aware of possible exposure.
Michael Anissimov
Michael Anissimov

Michael is a longtime wiseGEEK contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.

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Discussion Comments

anon311061

If an Alpha particle is a Helium nucleus, is it not easy to make it safe by adding two electrons to make the particle stable?

anon151604

I understand a little more. Thanks for the post. -Michigan

anon111200

Thank you tons for posting this. I understand much better now.I found this article to be interesting and pretty easy to understand.

anon109323

thank you for your help. now i actually know its use. thanks very much.

anon89623

I understand so much better now. Thank you.

anon89408

Thank you. It helped a lot.

anon89405

its kind of hard to understand. i think it needs to be explained more simply.

anon85723

This is an amazing factual piece of work. it really helped me answer my school homework questions

anon70398

excellent.

anon68541

I finally understand it. thanks wisegeek! very detailed and exactly what i wanted. From apawsey

anon64328

So essentially an alpha particle is a messed up helium nucleus?

anon56712

can these particles ingested in water kill or cause cancers? and can these particles be generated in the waste pool of a nuclear plant?

anon55371

Very good piece of work. Very detailed piece.

anon52694

Cool.

anon52052

this is absolutely outstanding.

anon45391

yay! thanks. i understand it now!

anon39105

Thank you for your article on Alpha particles. I'm studying for a radiography degree and its helped me hugely. Thanks guys

anon36756

Uhm... could this be explained really simply please? Kind of confusing... Thanks!

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