Cosmogenic 26Al was measured in six samples from two cores of the Keyes chondrite, previously analyzed for spallogenic 3He, 21Ne, and 38Ar. Specific activities varied from 68.9¿5.4 dpm/kg near the center (depth, ~30 cm) to 50.9¿3.7 near the postatmospheric surface (depth, ~3 cm). The data are consistent with an approximately linear decrease in 26Al activity with radial distance r from the center of Keyes: (26Al)obs/(26(Al)calc=1.04 (¿0.05)-0.0104(¿0.0032)(r). The measured 26Al (dpm/kg)/21Ne (10-8 cm3/g) ratio is constant at 6.13¿0.18 for the six samples, corresponding to an average atomic production ratio of 0.222 for the meteorite. |