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In-situ radiocarbon production by neutrons and muons in an Antarctic blue ice field at Scharffenbergbotnen; a status report.

K van der Borg, der M van, C Alderliesten, A M d, R N Lamers, J Oerlemans, M Thomassen, de W van


In the radiocarbon accelerator mass spectrometry ( (super 14) C AMS) analysis of gases obtained in a dry extraction from a 52-m Antarctic ice core, we observed (super 14) CO (sub 2) and (super 14) CO concentrations decreasing with depth. The concentrations are explained in terms of in-situ production by neutrons and captured muons in ablating ice. The ratio of the (super 14) CO (sub 2) concentration to that of (super 14) CO has been found to be constant at 1.9+ or -0.3. The ablation rates obtained of 42+ or -18 cm.yr (super -1) and 40+ or -13 cm.yr (super -1) for the neutron and muon components, respectively, are about three times higher than observed from stake readings. The discrepancy may point to an incomplete extraction of the dry extraction method. Using the constant ratio in (super 14) CO (sub 2) and (super 14) CO concentrations we correct for the in-situ component in the trapped (super 14) CO (sub 2) and deduce an age of 10,300+ or -900 BP for the ice core.


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