Irradiation history of the Kirin meteorite.

Cosmogenic nuclides have been studied in the Kirin chondrite (H5). Some experimental results obtained in samples sent to us (Nos. 1 and 4 fragments) are described. We measured the gamma rays of 50Mn, 26Al, 22Na and 60Co, using Ge(Li) detector systems. 53Mn was determine by an activation method based on 53Mn(n, γ)54Mn. The light rare gases were also measured by a mass spectrometer in one of the specimens. We compare our data with others and conclude that it is possible to read out the fossil records in the meteorite and interpret them by, 1) Multiple exposure history and 2) Depth effects in the production of cosmogenic nuclides in different geometries.