Primordial He accompanies only “strange” Xe (Xe-2 )
Xe-1 = “ Normal ” xenon occurs in the inner
Elemental abundances of primordial He linked with excess Xe-136 in “strange” Xe (Xe-2 ) was the first clear evidence that elements and isotopes never mixed in the supernova debris that formed the solar system [ Trans. Missouri Academy Sci. 9 (1975) pages 104-122].