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用吉林1号陨石的43块样品确定了吉林陨石的宇宙线和铀裂变径迹密度的深度剖面。这个深度剖面基本上反映吉林陨石第二(4π)照射阶段记录的银河宇宙线径迹。由钻孔A和B的径迹测定结果,求得吉林陨石通过大气层时的平均烧蚀厚度分别为11±4cm和14±5cm;在第一(2π)照射阶段,钻孔A“顶部”的最小屏蔽深度约为30cm。大约在小于0.4 Ma前,由于短期受热事件的影响,使通过大气层前母体的15—20cm厚的表层中的核径迹退火,由此导出母体近表面区的观测径迹密度与理论预期值发生偏离。 相似文献
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Using 43 documented drill core samples of the H_5-chondrite "Jilin" the depth profile of GCR-and fission track densities was established. The track profile essentially reflects the GCR-track record of the second (4π-) irradiation stage of "Jilin". Relics of the track record of the first (2π-) exposure are indicated by a deviation from the theoretical depth profile of the 4π-exposure. No Pu-244 fission is observed ia the fission track background near the meteorite center. The atmospheric ablation thickness of the two drill cores A and B normal and parallel to the assumed surface of the "Jilin" parent body was found to be 11±4 cm, respectively. A minimum shielding depth of the "top" part of core A during the 2π-exposure is estimated to be～30 cm. Near surface deviations of the experimental track data from theory are ascribed to a short-term moderate heating event (equivalent to 24h,～370℃) no more than 0.4 Ma ago. The resulting partial track annealing in a surface layer of ～15—20 cm thickness of t 相似文献
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