DIY Particle Physics-based things.

[YourEverydayWaffle]

I'm bored. Anybody know of do-it-yourself projects or experiments in the general field of particle physics? It might sound ridiculous, but it actually is not that complex to do these sort of things (i.e. Wine bottle electron accelerator, 100ml flask sonoluminescence "reactor", which are both real things). Just trying to find something fairly interesting to do. Goes to show how geeky I am.

[K^2]

Hm... If you can get/build a small electron gun and manage to draw decent vacuum, the e/m of electron experiment is fairly straight forward. What you do is set up as uniform a magnetic field as you can manage, typically with Helmholtz Coils and measure the radius of the loop the electron beam makes. It helps if you can get a bit of neon into your near-vacuum chamber, because it will make the beam that much easier to see. But even with rarified air, you can usually see the track if you pump enough electrons through it.

You will need a fairly high DC voltage source and a vacuum pump, which constitute the "dangerous" parts of the experiment. If you know how to handle that sort of equipment, it's pretty safe.

There is no need for anything fancy for electron gun. You can actually build it yourself. You will probably want to salvage a hot cathode from a radio lamp or similar, but other parts you can literally make out of aluminum can. You will need to set up accelerator potential and a focusing one. You want to be able to tune both independently, so that you get a nice, tight beam with whatever energy you want to give it. The accelerator potential will tell you kinetic energy of the electrons, as a multiple of elementary charge e. You can then work out the radius of the beam loop given magnetic field strength, and you can either tune the field strength or accelerator potential (or both!) to get a number of data points. The results will let you estimate electron's e/m ratio.

Naturally, you can also pick up an electron gun from a CRT screen. But these, typically, have a ton of different inputs you'd have to figure out. Either option has advantages and disadvantages, so go with what you are more comfortable with.

We have set up for this experiment at the department, and it's pretty straight forward. But the gun/vacuum chamber setup is pre-built, which makes this experiment just a number-crunching exercise. Your task would be a lot harder if you are trying to build it yourself.

Edited June 23, 2014 by K^2

[YourEverydayWaffle]

Hm... If you can get/build a small electron gun and manage to draw decent vacuum, the e/m of electron experiment is fairly straight forward. What you do is set up as uniform a magnetic field as you can manage, typically with Helmholtz Coils and measure the radius of the loop the electron beam makes. It helps if you can get a bit of neon into your near-vacuum chamber, because it will make the beam that much easier to see. But even with rarified air, you can usually see the track if you pump enough electrons through it.

You will need a fairly high DC voltage source and a vacuum pump, which constitute the "dangerous" parts of the experiment. If you know how to handle that sort of equipment, it's pretty safe.

There is no need for anything fancy for electron gun. You can actually build it yourself. You will probably want to salvage a hot cathode from a radio lamp or similar, but other parts you can literally make out of aluminum can. You will need to set up accelerator potential and a focusing one. You want to be able to tune both independently, so that you get a nice, tight beam with whatever energy you want to give it. The accelerator potential will tell you kinetic energy of the electrons, as a multiple of elementary charge e. You can then work out the radius of the beam loop given magnetic field strength, and you can either tune the field strength or accelerator potential (or both!) to get a number of data points. The results will let you estimate electron's e/m ratio.

Naturally, you can also pick up an electron gun from a CRT screen. But these, typically, have a ton of different inputs you'd have to figure out. Either option has advantages and disadvantages, so go with what you are more comfortable with.

We have set up for this experiment at the department, and it's pretty straight forward. But the gun/vacuum chamber setup is pre-built, which makes this experiment just a number-crunching exercise. Your task would be a lot harder if you are trying to build it yourself.

I've heard of this one before, but I didn't know about the simplicity of some parts. The DC power source is no problem either, as I have an neon sign transformer from a water-based fusion reactor build I did. Aren't home made things great? Thanks for the reply.

[Aghanim]

How do you create an electron accelerator that can create 100 W beam power? I'm just wondering

[K^2]

How do you create an electron accelerator that can create 100 W beam power? I'm just wondering

Beam power is not a very useful parameter for particle physics. The JLab accelerator produces a beam that's just 12W. But each electron in that beam carries 6GeV of energy. In contrast, an arc current when they open switches on power sub-stations can be carrying hundreds of kW of power. Yet, each electron is just a few keV, so it's not terribly useful for any experiments.

So the question shouldn't be just how much beam power you need, but what energy each particle carries, and how much current you need. Of course, knowing both, figuring out beam power is trivial.

[rtxoff]

How do you create an electron accelerator that can create 100 W beam power? I'm just wondering

You can learn how to build one by analysing how one of these is build.

[Skyler4856]

The double slit experiment is always fun!

[K^2]

The double slit experiment is always fun!

Also, kind of tricky to set up. I know, it sounds easy, but the fact that it was first performed only in 1961 should tell you something. (Other than with light, of course. But that's boring.) In contrast, e/m was done at the very end of 19th century. And as a rule of thumb, any experiment they managed in 19th century, you can reproduce at home. Though, some of the early radiation experiments I would not recommend trying to reproduce. For example, Rutherford's Experiment (which is, technically 20th cen, but still very easy to set up.) requires a strong alpha source. You don't need a lot, so you can probably get away with something perfectly legal, but I still can't recommend it to someone as an at-home experiment, because radiation.

A lot of particle physics experiments have radiation danger, of course. What's nice about e/m is that you can do it with energies on the order of keV, and that just produces some UV. If you go up to higher energies, working with an electron gun from CRT, for example, you'll start hitting dental X-Ray energies, and that's where you need to start worry about shielding. People have built cyclotrones at home, and you can get to hundreds of keV with that stuff. On one hand, it's really cool, because you can start doing some real particle physics at these energies. On another, safety requirements, as well as costs, are on a completely different level.

I might be able to think of some other experiments that can be done with either a very weak radioactive source or an electron gun, but the reason e/m comes to mind is because it's simple, about as safe as these get, and very visual. So it's actually fun to do.

Edit: Ah, speaking of visually interesting, simple, and still going after the same idea as double slit. So long as you are building/modifying an electron gun and a vacuum chamber, you can try doing electron crystallography. All you need is a target in front of your electron beam and a fluorescent screen a bit behind the target. You are a bit limited in choice of targets, compared to X-Ray or neutron source, but there are some fun ones. It's a bit hard to do this with a proper crystal at home, but if you do, say, powdered graphite, instead of dots, you'll get rings. Measuring radius of the rings will give you lattice constants of graphite. So this is a sort of 2 in 1 experiment. You do a solid state experiment, measuring lattice constants, but also confirming wave-particle duality of electrons, similar to double slit, which is a particle physics experiment.

Edited June 24, 2014 by K^2

[Phoenix Aerospace]

Ideas (easiest to hardest):

-Make graphene with scotch tape.

-Home-made cloud chamber. (try taping a magnet to the top!)

-Open a CRT monitor and replicate Thompson's experiment. (deviation of electrons)

-Play around with triboluminesence.

-Related to above, create x-rays with scotch tape. (requires vacuum chamber)

-Get some Am-241 out of a smoke detector and replicate Rutherford's experiment. (involves radioactive material)

Edited June 24, 2014 by Phoenix Aerospace

[K^2]

-Get some Am-241 out of a smoke detector and replicate Rutherford's experiment. (involves radioactive material)

I don't think smoke detector source is sufficient to do this with a simple fluorescent screen. And anything that is is a bit too radioactive. It's sort of why I warn against it in my post above.

You might be able to pull it off with a low intensity source using photo paper, which is a bit tricky to obtain and get developed these days. Might work with a roll of film, if you just do a 1D "cut" across the sphere around target. The advantage is that you can leave it for several days (might be useful to do an estimate of actual amount of time it should take) and get away with using a very weak source. Something you can either get from a smoke detector or even buy on eBay.

This would actually be fun to try. I'll do some math to see how feasible it is with film.

Edited June 24, 2014 by K^2

[Aghanim]

You don't open up a CRT tube, it will implode and explode and scatter all the glasses everywhere

[K^2]

You don't open up a CRT tube, it will implode and explode and scatter all the glasses everywhere

He said "open CRT monitor," which, to me, reads remove the housing.

If OP wants to salvage an electron gun off a CRT tube, he'd have to take one apart. Best thing to do is find one that's already trashed. Still lots of sharp glass, but at least you aren't dealing with it flying all over the place as it implodes.

[rtxoff]

He said "open CRT monitor," which, to me, reads remove the housing.

If OP wants to salvage an electron gun off a CRT tube, he'd have to take one apart. Best thing to do is find one that's already trashed. Still lots of sharp glass, but at least you aren't dealing with it flying all over the place as it implodes.

The implosion of an CRT tube is by far not that spectacular as you might think. Also there are ways to gently fill that vacuum with air like drilling a small hole into it.

[K^2]

I'm not talking about huge shards of glass flying out, as if a large petard went off inside. But small pieces of glass do end up flying everywhere if you just crack that thing. It's pretty much inevitable if you go with a brute force method. I suppose you could relieve the pressure gently, yeah. And then use glass cutter or heat stress fracturing to break off the relevant portion. But I've never been able to drill/break glass without it cracking in the wrong place. Maybe that's just me. But I'd definitely go for an already busted CRT tube if all I needed was the electron gun. It's just one less thing to go wrong.

In any case, drilling/cutting into a CRT tube would not be on my list of general recommendations. If you feel comfortable working with glass, sure, go for it. You probably know what you're doing with that thing. I don't. And I doubt a random person just tinkering with things does either.

[rtxoff]

Edit:

Here also a

Edited June 25, 2014 by gpisic

[K^2]

Fair enough. I would still expect it to go full Milhouse for me, so I still don't feel comfortable recommending it to anyone else. But if you feel like you can walk someone through all of the safety steps, go for it.

[tom1499]

PA's are troublesome. You need VERY high vacuum, which means very expensive equipment. One thing you can do with just under one thousand dollars is a Fusor. Farnsworth-Hirsch fusors are quite cool. You don't even need deuterium for glowy-scienceness!