You searched for: “primary cosmic rays”
primary cosmic rays (pl) (noun)
Primary cosmic rays are submicroscopic, electrically charged particles, largely protons, that travel in space at speeds nearly equal to that of light.

This entry is located in the following unit: cosmo-, cosm-, cosmico-, cosm, -cosmia, -cosmos, -cosmic, -cosmics, -cosmical, -cosmology, -cosms (page 8)