The Refractive Index of Silicon at Gamma Ray Energies

The index of refraction n(E_{\gamma})=1+\delta(E_{\gamma})+i\beta(E_{\gamma}) is split into a real part \delta and an absorptive part \beta. The absorptive part has the three well-known contributions to the cross section \sigma_{abs}: the photo effect, the Compton effect and the pair creation, but there is also the inelastic Delbr\"uck scattering. Second-order elastic scattering cross sections \sigma_{sca} with Rayleigh scattering (virtual photo effect), virtual Compton effect and Delbr\"uck scattering (virtual pair creation) can be calculated by integrals of the Kramers-Kronig dispersion relations from the cross section \sigma_{abs}. The real elastic scattering amplitudes are proportional to the refractive indices \delta_{photo}, \delta_{Compton} and \delta_{pair}. While for X-rays the negative \delta_{photo} dominates, we show for the first time experimentally and theoretically that the positive \delta_{pair} dominates for \gamma rays, opening a new era of \gamma optics applications, i.e. of nuclear photonics.Comment: 4 pages, 3 figure

Approximate relations and charts for low-speed stability derivatives of swept wings

Contains derivations, based on a simplified theory, of approximate relations for low-speed stability derivatives of swept wings. Method accounts for the effects and, in most cases, taper ratio. Charts, based on the derived relations, are presented for the stability derivatives of untapered swept wings. Calculated values of the derivatives are compared with experimental results

Туризм и внешняя торговля АР Крым: географические аспекты современного развития

Целью данной статьи является оценка современного состояния внешней торговли АР Крым и ее составляющей – туристской деятельности

Computerized cyclic voltammetric detection after HPLC of the antineoplastic agents etoposide, teniposide, adriamycin and its metabolite adriamycinol in urine samples

A computerized electrochemical detection system for application after HPLC, provided with a cyclic voltammetric oxidative and reductive module, is described for the on-line qualitative determination of electroactive antineoplastic agents and metabolites in urine samples, collected from cancer patients, following intravenous administration