| タイトル | Evidence for the constancy of the solar cosmic ray flux over the past ten million years - Mn-53 and Al-26 measurements |
| 著者（英） | Murrell, M. T.; Arnold, J. R.; Russ, G. P., III; Kohl, C. P. |
| 著者所属（英） | California Univ. |
| 発行日 | 1978-01-01 |
| 言語 | eng |
| 内容記述 | Mn-53 and Al-26 activities have been measured in fourteen samples carefully ground from the upper 1.5 cm of rock 68815 to discern whether the magnitude and shape of the solar cosmic ray (SCR) flux in the last 2 m.y. has differed from the recent SCR flux and that averaged over the last 10 m.y. Results yield no evidence that the SCR flux has varied among these time intervals. Assuming the appropriate erosion rates, the measured profiles of rock 68815 (with a 2 m.y. surface exposure) and of rocks 12002 and 14321 (saturated with respect to Mn-53 and Al-26) can all be fit with the SCR parameters of R sub zero = 100 MV and J = 70 protons/sq cm/sec (4 pi, energy greater than 10 MeV). The measured profiles of 68815 and 14310 are incompatible with the short surface exposure age (less than 3 m.y.) proposed for 14310 on the basis of track studies. Activity vs. depth profiles for three different faces of 68815, show surface activities nearly independent of sample inclination. |
| NASA分類 | LUNAR AND PLANETARY EXPLORATION |
| レポートNO | 79A39228 |
| 権利 | Copyright |
| URI | https://repository.exst.jaxa.jp/dspace/handle/a-is/426733 |
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