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(1998)Journal ArticleThe first results obtained using a SOI device for microdosimetry applications are presented. Microbeam and broadbeam spectroscopy methods are used for determining minority carrier lifetime and radiation damage constants. A spectroscopy model is presented which includes the majority of effects that impact spectral resolution. Charge collection statistics were found to substantially affect spectral resolution. Lateral diffusion effects significantly complicate charge collection
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(1996)Journal ArticleThe microstructural development during annealing of a cold-deformed 6061Al metal matrix composite (MMC) reinforced with either 3 or 20 mgrm diameter SiC particles has been investigated. The composites were compressed to low (< 10%) levels of strain and then annealed at either 350 or 450°C for different times. Microstructure examination was carried out by transmission electron microscopy and optical microscopy. The results reveal that prior grain boundaries and constituent particles are the dominant sites for recrystallization in both composites, although some nucleation was observed adjacent to the larger SiC particles. The concurrent presence of Mg2Si precipitates affected the progress of recrystallization.
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(1998)Journal ArticleWe have imaged the Circinus galaxy in the near-infrared [Fe ii] 1.64-μm and H2 2.12-μm lines, and derived velocity maps for the emission. The morphologies are strikingly different, but the velocity maps are very similar and consistent with simple rotation. We also present new radio continuum maps at 3 and 6 cm, which show a partially resolved nucleus with a flat spectral index. This suggests free–free absorption rather than self-absorption in a compact source. There is some evidence of radio jets close to the nucleus. The H2 emission, rather than the [Fe ii] as in NGC 1068, is extended along the jet axis and may be excited by jet-induced shocks either in a low-density medium or with rather slow shock speeds (v≲50 km s−1). We find that the star formation in the ring 10 arcsec from the nucleus began less than a few ×107 yr ago. Nearer the AGN, perhaps in and around the inferred torus, we detect extended [Fe ii] emission (including one prominent peak about 2 arcsec north of the AGN which could be due to a single young remnant), from which we derive a modest star formation rate of <1 M⊙ yr−1.
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(1997)Journal Article
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