A setup for simultaneous many-angle measurements of elastic backscattering cross sections
Abstract A scattering chamber is described, which was constructed and installed at the KN3000 Van de Graaff accelerator in Florence, for a systematic study of proton and alpha elastic backscattering cross sections on light nuclei, as a function of both bombarding energy and scattering angle. Sixteen silicon detectors, which can be cooled down to LN 2 temperature, have been mounted at backward angles from 95° to 170°. Test measurements show that an overall accuracy of the order of 1–2% is attainable for the cross section values. These measurements also point out that special care should be devoted to the determination of the effective target thickness under beam bombardment.
This work investigated analytically the band structure of photonic crystals (PCs) with alternate layers of left and right-handed materials in one-dimension. It was found that, under certain conditions, new peculiar band structures not seen in all right-handed material PCs appeared. We transformed the analytic dispersion relation into two cosine terms, and obtained an interesting band structure using the new form of dispersion equation. Conditions for obtaining such peculiar band structure were given.