Question

Alpha particles can be easily stopped by the simple sheet of paper. However, radiation from alpha emission is on average 20 times more damaging to chromosomes than equivalent amounts of beta and gamma radiation. What is an explanation for that? Is that related to the penetrating ability of particles? Explain why radiation therapy with alpha particles has a limited use in cancer treatment?

Answer 1

Beta and gamma radiations are highly peneetrating. But they cause less damage.

The reason for this ts their compositions.

A gamma radiation is simply an electromagnetic rediation, just like light, but with a much higher energy than light.

A beta partlcle is a fast moving electron (or a positron , which is an electron with a positive charge )

An alpha particle is basically a helium nucleus.

It contains 2 protons and 2 neutrons.

It has double the charge of a beta particle and almost 8000 times the mass of an electron.

This means that an alpha particle with much lower speed can gave very high momentum than beta or gamma rays.

that is why alpha radiation is more damaging than beta or gamma.

In radiation therapy, our aim is to make the radiation penetrate the human body, to where the cancer cells are, and get a high intensity in that region by focussing the radiation.

But alpha particles donot get past the human skin.

So, any cancer that is inside the human body can not be rached using alpha particles.