Dechanneling of alpha particles by carbon dissolved in palladium

The dechanneling effect of carbon atoms dissolved in palladium is measured. A method is described to obtain a solid solution of carbon atoms in palladium. The introduction and the elimination of carbon are controlled by electrical resistivity measurements. The dechanneling yield of α particles (E approximately 4 MeV) by these carbon atoms verifies the exponential law of attenuation of channeled particles. The average dechanneling cross-section by the carbon atoms is found equal to (4.6 +- 1) x 10-3 A2. This result is compared to the value obtained for hydrogen atoms in palladium and to the result of a theoretical calculation. The dechanneling effect is primarily attributed to the obstruction of the channels by the carbon atoms. The above comparison suggests that at room temperature the carbon atoms could occupy (totally or partially) the tetrahedral sites of the f.c.c. lattice of palladium. (author)