I was watching a video about quarks and they said that they made an experiment where they fired electrons into protons and saw how they bounced.
All this makes my head hurt like.. how do they do that? How to they see what happens when the electrons are fired? How so they see where they bounce?
You can’t observe all this with microscopes right? So how does it all work?
In: Chemistry
You don’t watch with a microscope, but you do have detectors.
One such detector is a phosphor screen, which is basically just a sheet of glass that’s been treated with chemicals that emit light when struck by certain particles. Electrons are one such particle.
So the first thing that you do is figure out a way to emit a beam of electrons. This actually isn’t that hard to do – you can look up instructions for making a basic beam online. Once you have your beam, you point it at your phosphor screen. When it’s struck by your beam, it will light up. Shine it directly at the screen, and you’ll have a bright spot. Move it around, and you’ll have a moving bright spot. This, by the way, is effectively how CRT TVs worked.
You’ve now established your beam, and you’ve established that you have a detector to tell where your beam is. Now you can point your beam at a target and see what happens. You know that it will behave in certain ways if nothing gets in the way. So if you see that the beam reacts differently, you can reasonably interpret that difference as the effect of your target.
On top of that, you also have some theories about what it would look like if a beam of electrons struck a certain target. The math is somewhat complicated, but you can model what an electron should do when it strikes a proton, and extrapolate that to what you would expect to see on your phosphor screen – maybe a dark spot where it should be light, maybe the light spot showing up somewhere other than where you’re pointing the beam. Whatever it is, you can make predictions, and you can then test those predictions with your physical apparatus.
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