Volume 395 - 37th International Cosmic Ray Conference (ICRC2021) - CRD - Cosmic Ray Direct
SuperTIGER Abundances of Galactic Cosmic Rays for the Atomic Number (Z) Interval 30 to 56
N.E. Walsh*, Y. Akaike, W.R. Binns, R.G. Bose, T.J. Brandt, D. Braun, N. Cannady, P.F. Dowkontt, T. Hams, M.H. Israel, J.F. Krizmanic, A.W. Labrador, J.T. Link, R.A. Mewaldt, J.W. Mitchell, R.P. Murphy, B.F. Rauch, K. Sakai, M. Sasaki, G. Simburger, E.C. Stone, T. Tatoli, J.E. Ward, M.E. Wiedenbeck, W.V. Zober and G.A. deNolfoet al. (click to show)
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Pre-published on: July 30, 2021
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Abstract
SuperTIGER (Super Trans-Iron Galactic Element Recorder) is a long-duration-balloon instrument that completed its first Antarctic flight during the 2012-2013 austral summer, spending 55 days at an average float altitude of 125,000 feet. SuperTIGER measured the relative abundances of Galactic cosmic-ray (GCR) nuclei with high statistical precision and well resolved individual element peaks from $_{10}$Ne to $_{40}$Zr. SuperTIGER also made exploratory measurements of the relative abundances up to $_{56}$Ba. Although the statistics are low for elements heavier than $_{40}$Zr, we present preliminary relative abundance measurements of charges $Z=41-56$ with individual element resolution. GCR measurements up to $_{40}$Zr support a source acceleration model where supernovae in OB associations preferentially accelerate refractory elements that are more readily embedded in interstellar dust grains than volatiles. In addition, injection into the GCR for both refractory and volatile elements appears to follow a charge dependence consistent with their grain sputtering cross sections. Our preliminary measurements of the $Z=41-56$ range suggest the existence of an alternative GCR source or acceleration model for $Z>40$ elements. We report progress in refining this interesting result.
DOI: https://doi.org/10.22323/1.395.0118
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