Common-path achromatic rotational-shearing coronagraph

To suppress starlight for direct exoplanet observation, we propose a common-path achromatic rotational-shearing coronagraph (CP-ARC), which is an interferocoronagraph with an angular-adjustable field rotator. The CP-ARC aims to maintain unwanted detection of stellar light, which can be suppressed incompletely by interference because of the finite diameter of the star. Compared to the previous interferocoronagraph, which had a nonadjustable 180° field rotation, the proposed CP-ARC can improve the coronagraphic contrast by several orders if the CP-ARC is combined with medium or large telescopes where the companion-star separation is optically resolved by more than a few Airy radii. The CP-ARC is made robust against mechanical disturbances due to the common-path interferometer principle.     

Structural and functional diagnostics of ultrafine components in condensed high-energy systems

The study deals with octogen (HMX) and aluminum, which are among the most widely used components of condensed high-energy systems. The structure, thermal behavior and combustion parameters were determined for the octogen-based monofuels and octogen-aluminum binary systems at different dispersity of components. Irrespective of differences in thermal behavior, monofuels obtained with standard and ultrafine octogen powders were shown to have virtually identical combustion parameters. In the binary systems, replacement of standard microsized aluminum by ultrafine one increases the combustion rate by a factor of 2.5, and completeness of the metal reaction (oxidation) by a factor of 4.     

Pulsed broadly tunable room-temperature Cr2+:CdS laser

We report the spectroscopic characteristics and laser properties of Cr²⁺:CdS. The emission lifetime of the exited state, ⁵E, of Cr²⁺ in CdS host was measured to be 0.93 μs at room temperature and 7.3 μs at liquid nitrogen temperature. The measured values of peak absorption and emission cross sections were found to be 1.4×10⁻¹⁸ and 1.1×10⁻¹⁸ cm² respectively. Room-temperature pulsed-laser operation was obtained under pumping by the 1.94 μm output of a Tm:YAP laser. The output of the free-running Cr²⁺:CdS laser was centered at ∼2.6 μm, and an absorbed energy slope efficiency of 38.8% was demonstrated. The passive crystal losses were measured to be less than 0.049 cm⁻¹ at the lasing wavelength. With an intracavity prism, the Cr²⁺:CdS laser was tuned from 2.18 to 3.32 μm.     

Quantum Dynamical R-Matrices and Quantum Frobenius Group

We propose an algebraic scheme for quantizing the rational Ruijsenaars-Schneider model in the R-matrix formalism. We introduce a special parametrization of the cotangent bundle over . In new variables the standard symplectic structure is described by a classical (Frobenius) r-matrix and by a new dynamical -matrix. Quantizing both of them we find the quantum L-operator algebra and construct its particular representation corresponding to the rational Ruijsenaars-Schneider system. Using the dual parametrization of the cotangent bundle we also derive the algebra for the L-operator of the hyperbolic Calogero-Moser system. Received: 24 January 1997 / Accepted: 17 March 1997     

Scattering by a point defect in a honeycomb lattice-an explicitly solvable model

State University, St. Petersburg. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 101, No. 2, pp. 272–281, November, 1994.     

Virasoro amplitude from theS N R24-orbifold sigma model

The four-tachyon scattering amplitude is derived from theS ^N R²⁴-orbifold sigma model in the largeN limit. The closed string interaction is described by a vertex that is a bosonic analog of the supersymmetric vertex recently proposed by Dijkgraaf, H. Verlinde, and E. Verlinde. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 114, No. 1, pp. 56–86 January, 1998.