| タイトル | Abundance of the Radioactive Be-10 in the Cosmic Radiation up to 2 GeVnucleon-l with the Balloon-borne Instrument ISOMAX1998 |
| 著者（英） | Barbier, L. M.; Geier, S.; Goebel, H.; deNolfo, G. A.; Menn, W.; Bremerich, M.; Hof, M.; Christian, E. R.; Gupta, S. K.; Hams, T. |
| 著者所属（英） | NASA Goddard Space Flight Center |
| 発行日 | 2004-01-01 |
| 言語 | eng |
| 内容記述 | The Isotope Magnet Experiment (ISOMAX) a balloon-borne superconducting magnet spectrometer was designed to measure the isotopic composition of the light isotopes (3 less than or equal to Z less than or equal to 8) of the cosmic radiation up to 4 GeV nucleon (exp -1) with a mass resolution of better than 0.25 amu by using the velocity vs. rigidity technique. To achieve this stringent mass resolution ISOMAX was comprised of three major detector systems, a magnetic rigidity spectrometer with a precision drift chamber tracker in conjunction with a three-layer time-of-flight system and two silica-aerogel Cherenkov counters for the velocity determination. A special emphasis of the ISOMAX program was the accurate measurement of radioactive Be-10 with respect to its stable neighbor isotope Be-9, which provides important constraints on the age of cosmic rays in the Galaxy. ISOMAX had its first balloon flight on August 4-5, 1998, from Lynn Lake, Manitoba, Canada. Thirteen hours of data were recorded during this flight at a residual atmosphere of less than 5 g per square centimeter. The isotopic ratio at the top of the atmosphere for Be-10/Be-9 was measured to be 0.195 plus or minus 0.036 (statistical) plus or minus 0.039 (systematic) between 0.26 - 1.03GeV nucleon (exp -1) and 0.317 plus or minus 0.109 (statistical) plus or minus 0.042 (systematic) between 1.13 - 2.03GeV nucleon(exp -1). This is the first measurement of its kind above 1 GeV nucleon (exp -1). ISOMAX results tend to be higher than predictions from current propagation models. |
| NASA分類 | Space Radiation |
| 権利 | No Copyright |
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