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We study morphological changes on the Si surface induced by the C60 ion beam under various irradiation conditions. The fluence and incident energy of the C60 ion beam was 1 × 1016–1 × 1019 ions/m2 and 50 keV–9 MeV, respectively. The beam's incident angle to the surface normal was 0° or 60°. As a result of the changes in these variables, three types of nanostructures were observed: concave and convex, stringlike, and ripple structures. Structure shapes or sizes varied with changes in the parameters. Almost all cases showed concave and convex structures at an incident angle of 0°. At a 60° incident angle, stringlike or ripple structures were formed. Stringlike structures were formed at higher incident energy, while ripple structures were formed at lower incident energy. We found that both stringlike and ripple structures can form from sputtering and thermal effects. The formation of string structure requires a thicker amorphous layer and the proper balance of sputtering and annealing. [ABSTRACT FROM AUTHOR]

Impacts of energetic C60 ions with energies of the order of MeV are excellent ionization methods for highly sensitive secondary ion (SI) mass spectrometry because they can provide SIs necessary for the identification of target materials in high emission yields with high reproducibility. As part of an investigation into their SI emission phenomena with the aim of controlling the mass-analyzed depth range, we measured and characterized the impact angle dependence of SI mass spectra for MeV C60 ion impacts, and found that shallower angle impacts of MeV C60 ions can provide surface-sensitive information through intense emission of surface-derived SIs. [ABSTRACT FROM AUTHOR]

We have developed a glass channel to guide ions heavier than protons and alpha particles with kinetic energies of several MeVs. The fluence of a 4 MeV-C4+ ion beam transmitted through the cylindrical glass channel (CGC) was measured by counting the number of etch pits using a CR39 solid-state nuclear track detector. After charge of the CGC using the incident ions with 31 nC, the fluence of the transmitted ions increased by 23%–26% at an angle of 0° with respect to the ion beam axis, compared to that before the charging process. In this case, the kinetic energy of the ions transmitted through the CGC maintained the incident kinetic energy of 4.0 MeV in absence of preceding charge up. [ABSTRACT FROM AUTHOR]

Codes are considered for correction and detection of unidirectional byte errors. A code construction based on the generalized concatenated code construction is proposed. This construction gives a lot of efficient codes. For example, from this construction, a 72-input-bit encoder of the triple unidirectional 8-bit-byte error-correcting and four-fold unidirectional 8-bit-byte error-detecting code with a length of 112 bits and rate 9/14 are obtained, whereas the ordinary triple 8-bit-byte error-correcting and four-fold 8-bit-byte error-detecting code of the same length has only 56 information bits and is of rate 1/2. Further, the proposed construction is generalized to one that gives efficient short-length codes.