Galactic Cosmic Ray Origins and OB Associations: Evidence from   SuperTIGER Observations of Elements $_{26}$Fe through $_{40}$Zr
  We report abundances of elements from $_{26}$Fe to $_{40}$Zr in the cosmic radiation measured by the SuperTIGER (Trans-Iron Galactic Element Recorder) instrument during 55 days of exposure on a long-duration balloon flight over Antarctica. These observations resolve elemental abundances in this charge range with single-element resolution and good statistics.   These results support a model of cosmic-ray origin in which the source material consists of a mixture of 19$^{+11}_{-6}$\% material from massive stars and $\sim$81\% normal interstellar medium (ISM) material with solar system abundances. The results also show a preferential acceleration of refractory elements (found in interstellar dust grains) by a factor of $\sim$4 over volatile elements (found in interstellar gas) ordered by atomic mass (A). Both the refractory and volatile elements show a mass-dependent enhancement with similar slopes. 
R. P. Murphy, M. Sasaki, W. R. Binns, T. J. Brandt, T. Hams, M. H.   Israel, A. W. Labrador, J. T. Link, R. A. Mewaldt, J. W...
astro-ph.HE