I understand something can become radioactive when it is polluted with radioactive material, The Claw (the crane which was used to clean up Chernobyl) comes into my mind. There is bad stuff on it -> radioactive.
But what about materials which are exposed to emission only? What changes in the material?
What happens for example when a steal plate is put inside LHC and bombarded with high energy particles? Does the protons collide with the electrons, become neutrons, so the iron in the “steal plate” changes into an isotope which is unstable, so it becomes radioactive?
In: Physics
The two typical ways an object becomes radioactive are either neutron bombardment or being placed in a beam line like you mentioned (LHC). Exposure to normal radioactive sealed sources aren’t strong enough to trigger a transmutation outside of neutron sources. To make an object radioactive it mainly involves knocking something loose from the nucleus (proton or neutron) or adding something to it to trigger a transmutation. There are other cases such as photofission which is a nucleus getting split by high energy photons (xray/gamma) and also secondary processes like electron capture which happens to balance proton to neutron ratios in the nucleus. Regardless of how it happens the object is referred to as being “activated” as it now has radioisotopes embedded in it.
Well, most of the time it doesn’t. When it does, it’s almost always from neutron radiation, where neutrons stick to the nucleus. A nucleus with the wrong number of neutrons is not stable. Other kinds of particle radiation like alpha particles *can* do this, but neutrons are hands down the most common.
Protons do exactly the same thing. They just stick to the nucleus, changing it into a different (and potentially unstable) isotope.
Alpha particles and neutrons can sometimes be absorbed by nuclei to produce radioactive isotopes. Probably the most well known example is Cobalt-60, which is produced when steel (which commonly contains a small amount of cobalt) is exposed to neutrons (for example in a nuclear reactor, or from a nuclear detonation) and stable Cobalt-59 absorbs one neutron to become Cobalt-60. Co-60 is a gamma-ray emitter with a relatively long half-life so it’s useful for certain medical and scientific applications, but has also caused a number of contamination incidents.
Its when materials are exposed to radiation, high-energy particles can collide with atoms in the material. This collision can alter the nucleus of the atom, making it unstable (radioactive). its like, in the LHC, protons can collide with nuclei, changing them into radioactive isotopes
Emissions are how stuff becomes radioactive compared to radioactive contamination (uranium dust for a crappy example).
Not all of the neutrons that hit an atom cause it to split. Some are absorbed into the atom giving it a +1 neutron,
If you do this enough, you can make fun elements like plutonium (used in nuclear weapons). But for materials that aren’t supposed to be plutonium, they “react” to that extra neutron by becoming radioactive.
If I shoved a chunk of gold into a reactor for long enough and if it was powerful enough, it would become gold 198 (radioactive). It doesn’t like that so it decays. That decay is what you see as radiation.
There’s a 50/50 chance I’ve made a mistake though, I’m not a physicist. Hopefully Cole’s law will kick in and a actual physicist will chime in
In most cases it is just the case of radioactive dust collecting on the equipment. You get dust in every crevice, in the grease, in the bearings, between the fibres in the cloth, etc. This is also why just washing things that have been in radioactive contaminated areas helps as the radioactive particles gets washed away. Although then you have an issue with radioactive waste water.
There are also a number of nuclear reactions that make things radioactive. Most of these issues is with neutron radiation from a nuclear reactor or exploding bomb. The neutron can hit an atoms so hard that it embeds itself into the nucleus and changes its atomic number. This then most likely makes it one of the many radioactive isotopes there are and it will start its decay chain to a more stable isotope. But alpha-radiation can also do the same although this is not as common.
“I understand something can become radioactive when it is polluted with radioactive material” incorrect. You dont turn radioactive from being covered in radioactive dust. You are just contaminated with microparticulates that radiate ionising electromagnetic radiation.
There is a process that CAN cause it, under specyfic conditions, called neutron activation – where a neutron with proper energy can be captured by atomic nucleus, basically transmuting that atom into either its radioactive isotope, or another atom that is radioactive. This obviously requires a certain type of ionising radiation – neutrons emmision, not i.e. gamma radiation or xrays. And it requires proper energies of said neutrons so that they are captured by target nucleus, instead of splitting it for example.
If I were to explain this to a real five year old, I’d start by saying that everything is made up of extremely tiny things called atoms. Atoms are so small that even microscopes can’t see them, but there are other devices that scientists have which can just barely see them. Radioactivity happens because sometimes atoms have too much stuff in them, so they spit out the extra stuff. The radioactivity is that extra stuff flying around by itself. But sometimes that stuff flies into other atoms because they are lucky enough to be on just the right path to bump into it. Then they might stick to those atoms. At that point, those atoms get too full and might spit it out again.
So at first you have a radioactive rock next to your toys, but eventually the toys start picking up the extra stuff and then they can’t hold onto it and begin spitting it out. That means that the toys are also radioactive, at least until they get rid of all that extra stuff.
After that explanation, I’d let the five year old ask more questions, we might get an inexpensive microscope, we could explore documentaries or science museums, etc. This would be an excellent way to fill in the gaps of their curiosity around the topic.
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