Observation of the 60Fe nucleosynthesis-clock isotope in galactic cosmic rays
Observation of the 60Fe nucleosynthesis-clock isotope in galactic cosmic rays
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DOI：
10.1126/science.aad6004
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发表时间：
2016-05-06
期刊：
影响因子：
56.9
通讯作者：
Wiedenbeck, M. E.
中科院分区：
文献类型：
--
作者：
Binns, W. R.;Israel, M. H.;Wiedenbeck, M. E.
铁-60（Fe-60）是宇宙射线中的一种放射性同位素，可以作为时钟来推断核合成和加速之间的时间上限。我们使用ACE-CRIS仪器收集了3.55 × 10（5）个铁原子核，其能量近似于195 - 500兆电子伏/核子，其中我们鉴定了15个Fe-60原子核。Fe-60/Fe-56源比为（7.5 +/- 2.9）x 10（-5）。在宇宙射线中检测到超新星产生的Fe-60意味着加速和运输到地球所需的时间不会大大超过Fe-60的半衰期260万年，并且Fe-60源距离不会大大超过宇宙射线在这段时间内可以扩散的距离，（小于或类似于）bar 1千秒差距。Fe-60的天然来源是附近的大质量恒星群。
Iron-60 (Fe-60) is a radioactive isotope in cosmic rays that serves as a clock to infer an upper limit on the time between nucleosynthesis and acceleration. We have used the ACE-CRIS instrument to collect 3.55 x 10(5) iron nuclei, with energies similar to 195 to similar to 500mega-electron volts per nucleon, of which we identify 15 Fe-60 nuclei. The Fe-60/Fe-56 source ratio is (7.5 +/- 2.9) x 10(-5). The detection of supernova-produced Fe-60 in cosmic rays implies that the time required for acceleration and transport to Earth does not greatly exceed the Fe-60 half-life of 2.6 million years and that the Fe-60 source distance does not greatly exceed the distance cosmic rays can diffuse over this time, (less than or similar to) under bar1 kiloparsec. A natural place for Fe-60 origin is in nearby clusters of massive stars.