Charged Particles and Ionization

[Vortexology]

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.

 

[mfb]

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.

 

[Vortexology]

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.

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.

 

[mfb]

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?

Right, the distance between the two points of decays correspond to the flight distance of the neutral particle.

 

[snorkack]

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.