Radiation is one of the most misunderstood of all scientific phenomena. It is a complete mystery to most people except for the unease that it is somehow dangerous. People are not even sure just how it is dangerous. Explore the actual facts about radiation to clear away the misconceptions.
Misconceptions About Radiation
People worry about nuclear war and the attendant radioactive fallout, or a nuclear reactor meltdown, but there are also many misconceptions about any kind of radiation being dangerous. Some people worry about radioactive objects making things around them radioactive or that any kind of radioactivity, in any amount, will kill them.
Learn more about the scientific method which deviates from the way it’s taught.
Is Radiation Really Dangerous?
Radiation can be dangerous in the wrong circumstances, resulting in cancer or even death. Radiation is not something to play around with without understanding it. But not all radiation that is around is dangerous. The people sitting with each other are radioactive, or a mother of a newborn is, too. The core point is that radioactivity can be dangerous, but it does not have to be, and understanding the difference can help.
True Meaning of Radiation
The word ‘radiation’ comes from Latin and means the emission of something. It also means to diverge from a center, and because of that, the word is used in some ambiguous ways. For instance, the electromagnetic radiation like the light from a lightbulb, or the signal from a radio station, or the heat emitted from a warm bed are all types of radiation. Dangerous radiation is called ionizing radiation, the variety that knocks electrons off from atoms. That radiation makes free radicals, which are atoms knocked off from molecules in a state to bind to whatever they encounter, damaging cells and causing health issues.
This is a transcript from the video series Understanding the Misconceptions of Science. Watch it now, on The Great Courses Plus.
Ionizing radiation originates in the nucleus of an atom. The energy that holds together the nucleus of atoms is 100,000 or a million times higher than the energy that holds atoms together. When nuclear radiation is emitted, it is higher energy and, therefore, more dangerous.
There are four main types of this kind of radiation, and they called: alpha, beta, gamma, and neutron. Each of them has a different characteristic and affects matter differently. Non-ionizing radiation, like microwaves, radio waves, laser light, and ultraviolet are very different from the ionizing types, with different effects.
Effects of Ionizing Radioactive Decay
In ionizing radioactive decay, something inside an atomic nucleus changes and it splits. This is called nuclear fission and is rare except inside nuclear reactors. The one kind of spontaneous fission that is fairly common is when a heavy nucleus spits out an alpha particle. An alpha particle is the nucleus of a helium atom, a bound state of two protons and two neutrons. The remaining nucleus has two fewer protons and neutrons and therefore the daughter nucleus has changed into a different element called alpha radiation. Alpha emitters are heavier elements, like radium, radon, uranium, and thorium. Radon is an especially dangerous element when breathed in.
Process of Beta Radiation
In beta radiation, a neutron in the nucleus of an atom changes into a proton, an electron, and an undetectable neutrino. The proton stays inside the nucleus, but the electron escapes. For historical reasons, these are called escaping electrons beta particles. Nuclei emitting beta radiation is heavy or light, for example, tritium, which is a form of heavy hydrogen, carbon 14, or strontium 90.
Gamma radiation occurs when an atomic nucleus emits a highly energetic photon. They are like x-rays’ bigger and more dangerous cousin. Both gamma rays and x-rays are electromagnetic radiation, with high energy to ionize atoms, with gamma rays doing it easily and x-rays having a little more trouble. When a nucleus emits a gamma ray, the nucleus does not change. Some gamma rays emitting nuclei are iodine 131, cesium 137, cobalt 60, and radium 226.
The number with each element is the combined number of protons and neutrons in the nucleus. For instance, carbon 14 means 6 protons and 8 neutrons. That is because for an atom to be carbon, it must have 6 protons. The more common form of carbon, like the kind that makes up humans, is carbon 12, with 6 protons and only 6 neutrons. Carbon 14 is radioactive and carbon 12 is not.
The final type of radiation is neutron radiation. As the name suggests, this is when the nucleus of an atom emits a neutron. Because the number of protons does not change, the element does not either, rather it changes into a different isotope of the same element. For instance, carbon 14 could emit a neutron and become carbon 13 but it does not do that. Carbon 14 decays via beta radiation.
Most neutron emitters are very heavy elements or a combination of two elements. In the combined case, the nuclear scientists place an alpha radiation-emitting substance near a lighter element, for example, beryllium. The beryllium absorbs the alpha particle and emits neutrons, called stimulated emission, where if an element just emits a neutron, it is called spontaneous emission.
Types of Dangerous Ionizing Radiation
There are four different types of ionizing radiation: alpha, beta, gamma, and neutron. Those types of radiation interact with matter differently and pose markedly different dangers to people. For instance, the alpha particle is slow, heavy, has a large electrical charge, and interacts very strongly as it passes through matter. Combined with its low velocity, alpha radiation is stopped very easily with a sheet of paper and it does not penetrate the skin but can be dangerous if inhaled.
Effects of Beta Radiation
Beta radiation is the emission of electrons. Electrons are about 8,000 times lower mass than alpha particles which means that, for the same amount of energy, they move much faster. In addition, they have half the electrical charge, interacting less with matter. Accordingly, they penetrate much more deeply than alpha particles. To stop a higher energy beta particle takes a couple layers of aluminum foil. There is one important feature of beta radiation that is not true of the other types. Beta particles are emitted simultaneously with neutrinos, the energy of beta particles is often low and lower energy beta particles penetrate even less. Beta radiation might penetrate the skin deeply enough to hit the part where live skin cells exist, but they rarely penetrate much deeper. In fact, even ordinary cloth provides some protection against beta radiation.
Fast Moving Gamma Radiation
Gamma radiation is more dangerous and Gamma particles are high energy photons, which move very fast having no electrical charge. Accordingly, they penetrate fairly deeply into matter and travel several feet in the air and several inches into people. However, they also are blocked easily by a thin layer of lead. Gamma particles are similar to x-rays and the lead dentists put over someone while taking x-rays, shields them from gamma rays.
It is worth noting that all three types of radiation stop in a material by either interacting with the electrons of the atoms they pass by or the electric field that holds the electrons in. By doing so, they knock electrons out of the atoms in a process called ionization.
Learn more about the difference between ionizing and non-ionizing radiation.
How Neutrons Work?
Neutron radiation is different and neutrons are heavy. They are a quarter as massive as the alpha particle and about 2,000 times heavier than the beta. They have no electrical charge, so they do not interact by bouncing into electrons. Instead, they plow through matter until they finally hit the nucleus of an atom.
Atomic nuclei occupy about a trillionth of the volume of ordinary matter, so neutrons penetrate very far. Because they have no charge, they do not ionize directly but knock a proton out of a nucleus and that proton ionizes. When they hit a nucleus of an atom, they convert it into a radioactive form of that element.
Using Neutron Shields
Neutrons bounce off nuclei, which tells about how they lose energy. If they hit high mass nuclei, they bounce; but if they hit low mass nuclei, the neutrons lose energy and slow down. If someone wants to shield themselves from neutrons, it is better to use materials that have a large amount of low-mass nuclei, for example, water with its H20, plastics, or waxes, which are good neutron shields.
Common Questions About Common Misconceptions and Facts About the Dangers of Radiation
Radiation can be dangerous in the wrong circumstances, and it is not something to play around with without understanding it. But not all radiation that is all around is dangerous. The people sitting with each other are radioactive, and the mother of a newborn is, too.
There are four different types of ionizing radiation: alpha, beta, gamma, and neutron. The different types of radiation interact with matter differently. They are vastly different and pose markedly different dangers to people. For instance, the alpha particle is slow, heavy, has a large electrical charge, and interacts very strongly as it passes through matter.
Gamma radiation is dangerous and gamma particles are high energy photons, which move very fast having no electrical charge. Accordingly, they penetrate fairly deeply into matter and can travel several feet in the air and several inches into people. However, they also are blocked easily by a thin layer of lead.
Beta particles are emitted simultaneously with neutrinos, the energy of beta particles is often low and lower energy beta particles penetrate even less. Beta radiation penetrates the skin deeply enough to hit the part where live skin cells exist, but it rarely penetrates much deeper. In fact, even ordinary cloth will provide some protection against beta radiation.