You Might Want to Know: What is ionizing radiation? Can it hurt us? How? What does it have to do with nuclear weapons? (Part Two)
This story is a little complicated, a little technical. It will take three entries to tell it. This is the second one. Since ionizing radiation is part of our lives, inescapably, it’s worth getting a handle on it.
Ionizing radiation can come in the form of electromagnetic waves that are transmitting high levels of energy.
It can also come in the form of particles, subatomic particles that are shot off in, for example, the natural radioactive decay of elements in the earth’s crust like radium and polonium. Plutonium also shoots off particles as it decays. Most of these are “alpha particles”—ions with two protons and two neutrons, the same number as in the nucleus of a helium atom, but lacking the two electrons that would normally go with the two protons. These alpha particles can be terribly damaging if inhaled but they are not very penetrating. A piece of paper can shield you from them.
To be protected from ionizing electromagnetic gamma rays, we’d need more than a foot of earth or a thick wall of lead.
What happens to the negatively charged electrons that are stripped off in the process of ionizing atoms? They themselves become a form of ionizing radiation, called beta radiation. Beta radiation is more penetrating that alpha radiation but much less penetrating than x-rays or gamma radiation.
Alpha, beta, and gamma radiation are all forms of ionizing radiation produced by nuclear fission.
Other high energy ionizing radiation is also arriving, constantly, from outer space, sometimes in the form of gamma rays and sometimes in the form of protons and other atomic and sub-atomic particles that carry a positive electrical charge and are travelling at very high speeds, like 1% of the speed of light—one thousand eight hundred sixty miles a second, sometimes even faster. Charged particles carrying that much energy can be ionizing.
Finally, neutrons. Neutrons are sub-atomic particles that carry no charge. Neutrons are what cause the chain reaction in a fissile fuel. When a nuclear chain reaction is going on, neutrons are always flying around--at inconceivable speeds.
Neutrons are even more penetrating than gamma rays. In the early 1970’s, we developed “enhanced radiation” bombs that didn’t have as much explosive force as other nuclear weapons but that shot out huge numbers of neutrons. We thought these weapons might be effective against tanks. They wouldn’t destroy the tanks, just kill the soldiers inside them. Same for people in bunkers or buildings.
Neutrons can cause serious harm to humans but they are only indirectly ionizing. For simplicity’s sake, we will leave them out of this account.
What is the harm ionizing radiation causes? Or can cause? Ionizing radiation that hits our cells can kill or alter them and cause mutations in our DNA. Altered cells can malfunction or become cancer. Altered DNA can produce mutations. That’s how, in general terms, ionizing radiation can harm us.
Carefully targeted ionizing radiation can be used to destroy cancer cells, however.
Are cells and DNA always altered or destroyed when hit with ionizing radiation? Not so we notice. Good thing too. As we’ve just seen, we are always getting hit with “background” ionizing radiation that comes from outer space and from the disintegration of radioactive atoms in the earth’s surface.
When we take an airplane flight, we get hit with more ionizing radiation than when we are on earth, several times more, actually, because of the ionizing radiation that is always coming in from outer space. Our atmosphere protects us pretty much from that kind of ionizing radiation. Not completely, but to a meaningful extent. Without our atmosphere, we’d be in trouble. We need to take care of it.
If you decide to take a trip to Mars, you’ll have to do without the atmosphere.
You can have my place.