This particles studied by astroparticle physics are the only ones in the nuclei of hyrdogen atoms
... into 
one helium atom, and 0.7% of the original mass of the hydrogen has... [DOC] [TLE] cosmic ray | physics | Britannica.com [PAR] Apr 15, 2016 ... Cosmic ray, a high-speed particleeither an atomic nucleus or an electronthat 
travels through space.