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Tracks of fission fragments from a californium-252 source have been revealed by graft copolymerization. A 15 percent solution of propenoic (acrylic) acid monomer was reacted with irradiated cellulose triacetate for 24 hours at 55 degrees C. Copolymer forms preferentially at the track sites and it can be dyed with rhodamine B because of its acid and hydrophylic properties. After the dyeing, the tracks were seen by using fluorescence microscopy.

Abstract-:-Chemical compositions determined using electron excited x-rays are reported for four interplanetary dust particles collected m the stratosphere. These analyses include measurements of carbon and oxygen abundances which are important elements in the~e. primitive materials. Spot analyses show very heterogeneous compositions on a micrometer scale although average composrtion approaches that of C1 carbonaceous chondrites. While the spot analyses show intermediate compositions between cometary dust and carbonaceous chondrites, the heterogeneity more closely resembles that of comet Halley dust particles.