We report abundances of elements from 26 Fe to 34 Se in the cosmic radiation measured during fifty days of exposure of the Trans-Iron Galactic Element Recorder (TIGER) balloon-borne instrument. These observations add support to the concept that the bulk of cosmic-ray acceleration takes place in OB associations, and they further support cosmicray acceleration models in which elements present in interstellar grains are accelerated preferentially compared with those found in interstellar gas.

We report abundances of elements from 26 Fe to 40 Zr in the cosmic radiation measured by the SuperTIGER (TransIron 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 6 11 % material from massive stars and ∼81% normal interstellar medium material with solar system abundances. The results also show a preferential acceleration of refractory elements (found in interstellar dust grains) by a factor of ∼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.

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Interactions of 10.6A GeV gold nuclei have been studied in nuclear emulsions. In a minimum bias sample of 1100 interactions, 4730 helium nuclei and 2102 heavy nuclei were emitted as fragments of the incident gold projectiles. The emission angles of these fragments have been measured and pseudorapidity distributions constructed. The multiplicity distributions have been considered separately for the light and heavy target nuclei in the emulsions and found to be relatively independent of the nature of the target, when studied in terms of the total charge remaining bound in the multiply charged fragments. These distributions have been compared with those reported by experiments that studied the multifragmentation of 0.6 and 1.0A GeV gold nuclei, and show relatively small but statistically significant differences that may be attributed to the differing energies or, possibly, to detection biases in the low energy data. We have also looked for evidence of phase changes in the description of multifragmentation and compared our conclusions with those of a study of 1.0A GeV gold nuclei interacting in a carbon target. We see evidence of behavior that is similar, but not entirely consistent, with that reported at the lower energy. Whether this is evidence for a true phase change in the state of the nuclear matter remains an open question. PACS number(s): 25.75+r, 29.40.Rg