Where should the radioactive cookies be placed?

Question

Suppose you were given three radioactive cookies, one is mixed with Alpha particles, the second with Beta, and the third with gamma. You are allowed to eat one, hold one, and place one in your pocket. Which cookie should be placed where so that you will receive the least radiation? Explain your answer

I saw in Wikipedia that when Alpha Particles are ingested, they are a great threat to our body due to their ionizing power. Please correct me if I'm wrong, so I thought there shouldn't be the one eaten.

Answer 1

Do you really have to eat one???  That could be a BAD idea regardless.

But if it's eat a cookie or get shot, then I'll go for the ones with the gamma radiation.  Since gammas are electromagnetic energy, most of them will pass through the body without any interaction at all.  But 100% of alpha particles and a large percentage of beta particles will be absorbed by the body and potentially do more harm than the gammas.

If you hold the one with betas, your hand will be getting a significant dose, but the alpha in your pocket will be pretty safe since the cloth will absorb the alphas.  But if you put the betas in your pocket some of them will be absorbed by the cloth but the rest will be near your gonads.  Not a good idea if you are planning on children.

But if you do put the beta cookie in your pocket and hold the alpha cookie that would result in the least radiation exposure because of the cloth absorbing betas, and the dead skin on the palm of your hand absorbing the alphas.

So I would eat the gammas, pocket the betas and hold the alphas, and perhaps glow in the dark.

Don't believe me?  It didn't take long to find a reference to prove my point:

Type of radiation: A layer of dead skin or a few inches of air stops alpha particles; more material is needed to stop beta particles,  which are lighter and faster. Substantial shielding is needed to block gamma rays, which are more penetrating.

Form of material: Alpha and beta emitters do little harm outside the body because they are easily stopped. Inside the body, though, they can do much damage.

This comes from http://www.fas.org/irp/crs/RS21528.pdf