Do cosmic ray particles ever undergo (nuclear)fusion with atmospheric (or other) particles they hit?

Factual Questions
1

In the thread about an apple sized meteor that hits the Earth while moving at 0.9c, there is a link to an XKCD Q&A about a baseball hitting the Earth at the same relativistic speed. In the XKCD answer, it’s mentioned how atoms in the molecules of the ball’s surface would undergo fusion with atoms in air molecules that the ball encounters. Assuming that’s correct, I wondered whether the same thing might occur with cosmic rays as they traverse the atmosphere, since some cosmic ray particles are sometimes traveling at close to light speed.

So, two questions, please

  • at least in theory, do some cosmic ray particles (such as alpha particles) ever undergo fusion with atmospheric atoms (or other particle) they encounter?
  • if so, can we detect the radiation that would be emitted as a result (have we?)

Thanks!

2

Can’t answer with any authority but extremely high energy particles from space do strike the atmosphere from time to time. Its rare but the only reason we even know about them is the radiation emitted from the collisions.

3

Sure thing. The process is called cosmic ray spallation, though I think fission processes are more common than fusion processes. Certain isotopes, so-called cosmogenic nuclides, wouldn’t exist on Earth if not for this process.

4

Ah, I had actually seen the article on spallation but did not think it was referring to fusion of cosmic ray particles and Earth’s atmosphere particles but, rather, to either 1. fission of particles in either the interstellar or terrrestrial atmosheres by cosmic rays or 2. nuclear fusion, but only involving cosmic rays and particles of the interstellar medium (and not the Earth’s atmosphere)

So, just to be clear, let me ask: is it the case that nuclear fusion can occur when a cosmic ray strikes a particle of the Earth’s atmosphere?

5

Hmm, yeah, upon further examination, those almost all appear to be fission processes in the sense that Z decreases. The exception is the reaction [sup]18[/sup]O + p -> [sup]18[/sup]N + n, but the A doesn’t change in that one. There are also several processes which are of the form [sup]A[/sup][sub]Z[/sub]X + n -> [sup]A+1[/sup][sub]Z[/sub]X + γ, but none of the form [sup]A[/sup][sub]Z[/sub]X + p -> [sup]A+1[/sup][sub]Z+1[/sub]X’ + γ.