| Budget Amount *help |
¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2005: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 2004: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Research Abstract |
We carried out this project during two years. First year, we investigated the energy-loss DE(n) of incident hydrogen cluster ions Hn+ traversing carbon, where all particles are assumed to be fully stripped and exploded via coulomb repulsive interaction. Here we define the ratio R=DE(n)/(n DE(1)). Above about 60 keV/u, the calculated results are always over unity and approach unity with increasing foil thickness. This is in good agreement with the experimental data. On the other hand, below that energy our theoretical result is over unity but the experimental data is less than unity. It contrast implies that the incident cluster will bind a few electrons. We also presented the impact-parameter-dependent ionization probability P(b) on the basis of hydrogen-like model. Using this P(b), we calculated the multiple ionization cross sections of C60 fullerene and diatom molecular target by swift ion impacts. They are in rather good agreement with the experimental data. Next year, we investigated the secondary electron emission yield by carbon cluster impacts on the basis of three-step model : (1)the excitation of electrons in a solid by an incident cluster, (2)transportation of those excited electrons to the exit surface, and (3)the overcome of the surface potential barrier. The first process includes the cluster effect of our interest. The recent experiment measured the energy spectrum Dg(n)/DE of electrons emitted from carbon induced by the 0.24 MeV/atom carbon cluster Cn+ (n=1-8). There the negative cluster effect was reported in the relative energy spectra, R=(1/n) Dg(n)/DE/Dg(1)/DE. We estimated this quantity by regarding the target electron system as an electron gas, where the dynamic response is described by the dielectric function. As a result, we obtain good agreement to a considerable extent. Quantitatively speaking, however, there is some room to need further analysis including other processes.
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