Interstellar medium lithium

Knauth DC, Eederman SR, Lambert DL, Crane P (2000) Newly synthesized lithium in the interstellar medium. 

Helium fusion moves directly from helium to carbon, leaping across the lithium-beryllium-boron trio. These nuclei are not produced in stars. Indeed, they are destroyed there, as a result of their excessive fragility. They are generated in the interstellar medium by collisions between high energy nuclei and protons and helium nuclei at rest, and also by the opposite process which amounts to swapping over target and projectile, as already mentioned. 

It is appropriate to begin this lecture with a diagram from the review of Shapiro Silberberg, 1970, which compares the abundances of elements in the cosmic radiation with solar system abundances. This classic measurement is one of the foundations of cosmic-ray physics. The elements lithium, beryllium and boron are quite abundant among cosmic rays even though they constitute only a tiny fraction of the material in the solar system and the interstellar medium. This fact is understood largely as the result of spallation of the... 

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