Does the radiation require matter

Answer 1

Radiation has a profound effect on matter. Particularly in forms where it has high energy. There are basically two kinds of radiation, and they are electromagnetic energy and particulate radiation. Low energy electromagnetic radiation isn't generally hazardous, as long as the field strengths are low. You wouldn't want to stand in front of a radar antenna when it's radiating, but we are swept by low power electromagnet energy all the time. Those so-called radio waves are everywhere. Light is this kind of energy, too, and it's not too bad. But at higher energies, electromagnetic radiation is a hazard. Particulate radiation is straight up a problem. We often refer to particulate and high energy electromagnetic radiation as ionizing radiation, and both kinds have the ability to do some damage. Jump in the ride, fasten your seatbelt and we'll take a cruise into the quantum mechanical hood to check it out. Pay attention to the scenery along the way so you'll be up to speed when we get there. Matter is composed of atoms. Atomic nuclei are tightly bound protons and neutrons (1H excepted) with electrons hanging out in the electron clouds around them. Also, there are chemical bonds between atoms in a lot of different kinds of matter. These bonds involve the borrowing and loaning of electrons (the so-called ionic bonds) or the sharing of electrons (the so-called covalent bonds). That's matter, and now we're going to see what happens when we shoot stuff at it. Incoming! If electromagnetic (EM) radiation of sufficient energy slices into matter, things happen - and they ain't good. A general term for this high energy EM radiation is gamma rays. Sometimes we include the "hard" X-rays, the highest energy X-rays, in this group. The radiation can interact with chemical bonds, particularly the lower energy covalent bonds, and break them. If those bonds were in living material, this could (and does) affect injury. And if the molecules whose bonds are being broken are DNA, genetic damage results. That kind of damage is very, very hard for living things to correct. Other cellular or tissue damage has a better chance of being repairable. That ionizing EM radiation can also kick electrons out of the electron cloud of individual atoms, thus directly ionizing them. This creates havoc in living material. It should be noted that the radiation has to give up some of its energy when it "hammers" atoms or molecular bonds, but this is high energy radiation. It can do a lot of damage. And it can penetrate, too. When lower energy radiation comes into contact with a substance, it can't do as much damage. Sunlight on skin can do damage through prolonged exposure, but it is primarily the ultraviolet (UV) light that poses a hazard. It's the skin that takes the hit, and not deep tissue. A bit of sun is actually good for you. Anyway, the stuff we're talking about is of much higher energy (higher frequency, shorter wavelength). Shielding against this kind of radiation takes dense material. Lead is good, and it is in common use because it is abundant, cheap and easy to fabricate. We could use heavier (more dense) material, but who can afford, say, iridium or osmium? So we've got penetrating ionizing electromagnetic radiation slamming into stuff. But there is an unpleasant "extra" that is possible, and it's almost magical. If EM radiation of sufficient energy (1.022 MeV or higher) swings by an atomic nucleus, a chunk of its energy can be converted into matter. You're gonna love this. The phenomenon is called pair production, and both an electron and a positron (an anti-electron - antimatter!) are created out of pure electromagnetic energy! They come flying away from the event, and they can do some damage by ionizing stuff. The two particles represent (no big surprise) particulate radiation. The electron and positron created in pair production will ionize nearby atoms (affecting chemical bonding if there is any). They will do this as they give up energy and slow down in what are called scattering events. And the piece de resistance is that at some point the positron will come into contact with an electron, and the two will mutually annihilate each other. The result will be a pair of high energy electromagnetic rays. And we're back where we started with this pair of what are called gamma rays slicing through stuff and causing more disruption of atomic and molecular structures. Bad news? You ain't seen nothin' yet. Particulate radiation is particularly nasty. It does not, in general, have the penetrating power of electromagnetic ionizing radiation, but let's check it out. Electrons, protons and neutrons, the building blocks of matter, can become ionizing radiation. We've glimpsed the electron in action. It has a small mass, and even an energetic one can be stopped by a sheet of aluminum foil. Protons are over 1800 times more massive. They can do some serious damage, too. The neutron is a different story. You remember that it has no charge, so this bad boy has some serious penetrating power. It takes atomic nuclei to slow (scatter) and stop this guy, and hydrogen is particularly good at it. Friendly hydrogen has a nucleus that is just a proton, and hydrogen is abundant in water. Plastic, too. Oh, what about combinations of these particles? The helium nucleus is usually composed of a pair of protons and a pair of neutrons. When this particle is released as radiation, we call it an alpha particle. It doesn't travel far in air, and a sheet of paper will block it, but it does some heavy ionizing when it gets loose. It is a hazard when any radioactive material that decays by alpha emission get airborne and we inhale it. Now we have a radioactive source inside us. It doesn't get much worse. The alpha particle, the proton, the neutron, the electron and the positron are all products of radioactive decay. Different types of radioactive decay generate each of the "flavors" of particulate radiation, naturally. We've touched on all the basics here, probably. And we've leaned toward biochemical "matter" when we talked about interaction. We could have delved into, say, the damage caused to the steel of a nuclear reactor vessel by the neutron bombardment it takes during its lifetime, but we wanted to roll the areas to just cover basics. Hope we did it adequately.

Answer 2

Gamma rays "disappear" when they are absorbed. Gamma rays are high energy electromagnetic radiation (EMR), and they are produced by nuclear events in stars, black holes, radioactive decay and the like. These high energy photons have a remarkable ability to penetrate matter. As they come in "contact" with any matter, however, they have a chance of transferring some of their energy to that matter. This is called scattering, and as regards scattering of high energy electromagnetic radiation, it is generally called Compton scattering. Lower energy is looked at as photoelectric effect. Also, the gamma rays can transfer a little or a lot of energy, depending on some variables. The radiation comes away from the scattering event at lower energy, and continues to "run into stuff" until its energy is all absorbed by the medium. Note that as a gamma ray gives up energy in the scattering events, its energy drops. It's no longer a gamma ray at some point, and it becomes less able to penetrate more matter. So as a gamma ray starts to "meet resistance" and give up energy in increments, its remaining energy is quickly dissipated and absorbed by the material it is "stuck" in. It should be mentioned that this is the scattering and absorption of the electromagnetic energy. It does not touch on pair production, which is another possibility with gamma rays that have a sufficiently high energy and meet the threshold for the phenomenon of pair production. The phenomenon of pair production is covered in another question. Links are provided below.

Answer 3

Photons interact with valence electrons easily, in a typicall exp, the molecules or atoms start at lower energy and go to the high energy level upon absorption of radiations of appropriate wavelength. Energy of the radiations must be equal to the energy difference between the two levels only then the absorption would occur.

Answer 4

When radiation hits an object it can do 3 things. Be absorbed, be transmitted, or be reflected.

Answer 5

no