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Energy spectra and angular distributions of quasifree electron bremsstrahlung (QFEB) induced by 20-MeV-proton bombardments of a Be target have been measured with a Si (Li) detector. The Doppler shift of QFEB is clearly observed in the energy spectra and depends on the observation angle. The production cross section calculated from a free-electron approximation is compared with the experimental result and the agreement is quite satisfactory. The spectral shape near the high-energy end point of the QFEB definitely reflects the velocity distribution of the orbital electrons of the target atom. Angular distributions of secondary-electron bremsstrahlung were also measured and are compared with a calculation which includes relativistic retardation effects.

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In this study, the optical constants of gold nanoparticles are evaluated for surface plasmon-based sensor applications. Using an effective medium approximation (EMA) and ellipsometry, approaches to monitor the self-assembly of gold nanoparticles are also demonstrated. Spectroscopic ellipsometric parameters measured ðtan É; cos ÁÞ before and after adding gold nanoparticles to a substrate are used to calculate the optical constants of gold nanoparticles. The film thickness is measured by grazing incidence X-ray reflectivity (XRR). The optical constants (refractive index, extinction coefficient) of gold nanoparticles can be obtained from the measured ellipsometric parameters and thickness. We also show that particles density can be well predicted and detected nondestructively by this method.

Transmission losses versus fiber end offset separation, and angular misalignment of graded index fibers excited by an incoherent source, have been measured in two independent experiments. The measurement setup, fiber diameter, and length were different in the two experiments, yet the measurement results are strikingly similar. The loss measurements clearly show that transverse offset is much more critical in connector and splice design than angular misalignment and end separation. Two‐tenths of the fiber core radius in transverse offset alone may cause 0.5 dB loss while one fiber core radius in axial separation combined with 1° in angular misalignment may cause 0.5 dB loss.