Nuclear time-reversal violation and the Schiff moment of 225Ra

We present a comprehensive mean-field calculation of the Schiff moment of the nucleus 225Ra, the quantity which determines the static electric dipole moment of the corresponding atom if time-reversal (T) invariance is violated in the nucleus. The calculation breaks all possible intrinsic symmetries of the nuclear mean field and includes, in particular, both exchange and direct terms from the full finite-range T-violating nucleon-nucleon interaction, and the effects of short-range correlations. The resulting Schiff moment, which depends on three unknown T-violating pion-nucleon coupling constants, is much larger than in 199Hg, the isotope with the best current experimental limit on its atomic electric-dipole moment.Comment: 4 pages, 2 figures; this version (references added) to be published in PR

New Observations of Balmer Continuum Flux in Solar Flares, Instrument Description and First Results

Increase in the Balmer continuum radiation during solar flares was predicted by various authors but never firmly confirmed observationally using ground-based slit spectrographs. Here we describe a new post-focal instrument - Image Selector - enabling to measure the Balmer continuum flux from the whole flare area, in analogy of successful detections of flaring dMe stars. The system was developed and put into operation at the horizontal solar telescope HSFA-2 of the Ond\v{r}ejov Observatory. We measure the total flux by a fast spectrometer from a limited but well defined region on the solar disk. Using a system of diaphragms, the disturbing contribution of a bright solar disk can be eliminated as much as possible. Light curves of the measured flux in the spectral range 350 - 440 nm are processed, together with the H{\alpha} images of the flaring area delimited by the appropriate diaphragm. The spectral flux data are flat-fielded, calibrated and processed to be compared with model predictions. Our analysis of the data proves that the described device is sufficiently sensitive to detect variations in the Balmer continuum during solar flares. Assuming that the Balmer-continuum kernels have at least a similar size as those visible in H\alpha, we find the flux increase in the Balmer continuum to reach 230 % - 550 % of the quiet continuum during the observed X-class flare. We also found temporal changes in the Balmer continuum flux starting well before the onset of the flare in H{\alpha}.Comment: 12 pages, 4 figure

Dual aperture multispectral Schmidt objective

A dual aperture, off-axis catadioptic Schmidt objective is described. It is formed by symmetrically aligning two pairs of Schmidt objectives on opposite sides of a common plane (x,z). Each objective has a spherical primary mirror with a spherical focal plane and center of curvature aligned along an optic axis laterally spaced apart from the common plane. A multiprism beamsplitter with buried dichroic layers and a convex entrance and concave exit surfaces optically concentric to the center of curvature may be positioned at the focal plane. The primary mirrors of each objective may be connected rigidly together and may have equal or unequal focal lengths

Dufour and Soret Effects of a Transient Free Convective Flow with Radiative Heat Transfer Past a Flat Plate Moving Through a Binary Mixture.

An approximate numerical solution for the Dufour and Soret effects of a transient free convective flow with radiative heat transfer past a flat plate moving through a binary mixture for a Sisko fluid has been obtained by solving the governing equations using numerical technique. Numerical calculations are carried out for different values of dimensionless parameters and an analysis of the results obtained shows that the flow is influenced appreciably by the chemical reaction, heat source and suction or injection at the wall and also the influence of Dufour and Soret in Sisko fluid. A parametric study illustrating the influence of H and m on the skin friction, Nusselt number, and Sherwood number is conducted. The obtained results are presented graphically and in tabular form and physical aspects of the problem are discussed