Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Charged Particles and Ionization

  1. Dec 6, 2012 #1
    I'm studying A Level physics. I've read that a bubble chamber only shows up particles with a charge, as they ionize the hydrogen in the chamber, leaving tracks, whereas neutral particles don't show up. Is it therefore true then that only charged particles ionize? Because UV-radiation is ionizing and photons don't have a charge.

    Is it that charged particles are the only ones to ionize in the circumstances, i.e. in hydrogen?

    Hope this makes sense.
     
  2. jcsd
  3. Dec 6, 2012 #2

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    Photons can ionize atoms, but they are destroyed in the process (or lose a significant fraction of their energy) - they do not leave tracks in the bubble chamber. The electrons which were hit by the photons can leave those tracks, however.
     
  4. Dec 6, 2012 #3
    So say if a charged particle decays and one of the products is neutral, which then goes on to decay into two oppositely charged particles, then the distance where the track disappears - I.e where the neutral particle was - is caused by the time it takes for that particle to be destroyed? Sorry I'm still a bit confused about this.
     
  5. Dec 6, 2012 #4

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    Right, the distance between the two points of decays correspond to the flight distance of the neutral particle.
     
  6. Dec 7, 2012 #5
    Neutral particles can ionize, but they do so only on rare close collisions. For example a photon ionizes on each Compton scattering event, giving a large amount of energy to a single charged electron, but then passes a long distance without any interaction save slight retardation and refraction. A neutron ionizes when it bounces off a proton - but these are rare events, and most of them give a lot of energy to the proton. Small energy collisions are possible, but these are especially rare - they only happen on a rare glancing collisions.

    Whereas a charged particle has a long range electric field. It generates a few high energy collisions on direct hits to charge centres, but a lot of low energy ionization events at large distances. It is these low energy ionizations that form a track.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Charged Particles and Ionization
  1. Charged Particles (Replies: 3)

  2. Particle charges? (Replies: 11)

Loading...