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Isolation of protons and alpha particle

  1. Jan 5, 2015 #1
    Hi, I wanted to ionize hydrogen and helium to get protons and alpha particles. I then want to smash the protons into the alpha particles. Is it better to accelerate both the alpha particle and the proton or just keep the alpha particle as a target for the proton to hit? Or is there a better way to do this without ionization?
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  3. Jan 5, 2015 #2


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    What does your test apparatus support? What equipment do you have in your lab?
  4. Jan 5, 2015 #3
    I don't have a lab -- just theoretically, which would be easier to do?
  5. Jan 5, 2015 #4


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    What is the objective of this exercise?

    One cannot accelerate a neutral atom. Usually, one ionizes the atoms, and if necessarily neutralizes it afterward through recombination with an electron.

    One could do colliding beams as it is difficult to hit alpha particles in a gas.
  6. Jan 5, 2015 #5


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    You need charged particles for acceleration.

    Getting two accelerated beams to interact is quite difficult (particle colliders are incredibly complex, precise technologies). Even worse if your two beams are different.

    You are better off (in terms of ease) to have a stationary target, but this depends on what energy you want to accelerate at (at high enough energies you're going to want to have colliding beams, but at those energies, I'd be wondering why you are colliding protons and alphas). Personally, at low enough energies, I would be making use of a polyethylene target ((C2H4)n), and not bothering with a gas target -- gas targets are hard to do.

    But what do you want to do?
  7. Jan 6, 2015 #6
    My goal is to create and detect positrons through particle collision.
  8. Jan 6, 2015 #7
    I really want to detect the positrons created in the collision, I thought originally that it would be easiest to do that by colliding a proton with a stationary alpha, but now I'm not so sure (I'm very new to this field so I have very little experience)
  9. Jan 6, 2015 #8


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    Do you just want to detect positrons? If so it would be a lot less trouble to just get a sample of Na-22 which decays by positron emission. It is used for medical purposes such as PET.
  10. Jan 6, 2015 #9
    Yes, the ultimate goal is to detect positrons, but it would be nice to see some quarks or maybe an antineutrino resulting from the collision. But you are right; to make sure that my positron detector even works, I should try some Na-22.
  11. Jan 6, 2015 #10


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    You can't detect quarks directly.
  12. Jan 6, 2015 #11


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    And neutrinos aren't exactly a easy to detect.

    Could you write out the reaction that you expect to happen? In terms of α+p → ?

    I'm afraid I don't quite understand what you're trying to do. (where are the positrons coming from in this collision?) In nuclear physics, you'd mostly only get elastic scattering, and some 5Li which lasts for, ooh, about half a zeptosecond. It sounds like you are wanting to do particle physics, but in that case, I don't see the benefit in using α+p.

    Either way, you can't see quarks directly ever, and antineutrinos require detectors that look like this: http://i1-news.softpedia-static.com/images/news2/Electron-Antineutrinos-Detected-2.jpg

    In any case, it sounds like you're not talking totally hypothetically here (if you're talking about a positron detector). In which case, I strongly discourage you from trying to make a particle accelerator. Besides being incredibly technically challenging to do what you want to do, it's also a really good way of getting yourself killed (either slowly, or quickly) if you don't know what you're doing.
  13. Jan 6, 2015 #12
    I was being hypothetical but that is if I were to try to make one in the future -- in which case you are right; I'm probably not going to because of the health risks.

    Would you think QuantumPion's idea of using radioactive sodium would be safer?
  14. Jan 6, 2015 #13


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    Well, I'd say that 22Na is differently dangerous, rather than necessarily less. You're less likely to electrocute yourself, but the good thing about a particle accelerator is that when you turn it off, the radiation goes away (mostly, barring whatever you've activated). 22Na is always radioactive.

    It's a matter of knowing what you are doing, really. You need to know enough about radiation safety to keep yourself and others safe.

    You should only ever have a small quantity, you should monitor your radiation dose (and know what an acceptable dose is), you should be careful not to contaminate any surfaces (if you've got an open source), you should wear gloves (if you've got an open source), you should not expose yourself unnecessarily (don't put it in your pockets, or hold it in your hand), and you should store it in a lead enclosure.

    (ETA: Not intended to be a complete list. Not intended to be professional advice)

    Do you have a university or college nearby? Perhaps you can use their facilities & guidance.

    What's your detector? Maybe we can come up with an alternative. (If it's a cloud or bubble chamber, you could just use cosmic rays).
  15. Jan 7, 2015 #14
    I live close enough to Michigan State University, and they have a working cyclotron, so perhaps I should consult them.

    The detector I was talking about is a cloud chamber -- so you're saying I could potentially detect positrons in cosmic rays?
  16. Jan 7, 2015 #15


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    MSU doesn't just have a working cyclotron, they have perhaps the strongest nuclear physics department in the US. But anywhere that teaches some undergrad physics should have some 22Na - it's very standard for undergrads. They also have a bunch of outreach people at NSCL, IIRC. All they can do is say no, after all!

    Not only can you detect positrons in cosmic rays, that's how they were found in the first place! (Carl Anderson, nobel prize in physics, 1936. http://d1jqu7g1y74ds1.cloudfront.net/wp-content/uploads/2009/12/andersonpositron.gif)
    Here's a great video from MIT http://video.mit.edu/watch/cloud-chamber-4058/ You should be able to see electrons and positrons, and verify that they go in the right direction, with respect to whatever magnetic field you put on the chamber (presuming you're doing that). You'll also see alphas and all that.
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