On ramification theory in the imperfect residue field case

We consider the class of complete discretely valued fields such that the residue field is of prime characteristic p and the cardinality of a $p$-base is 1. This class includes two-dimensional local and local-global fields. A new definition of ramification filtration for such fields is given. It appears that a Hasse-Herbrand type functions can be defined with all the usual properties. Therefore, a theory of upper ramification groups, as well as the ramification theory of infinite extensions, can be developed. Next, we consider an equal characteristic two-dimensional local field $K$. We introduce some filtration on the second K-group of a given field. This filtration is other than the filtration induced by the valuation. We prove that the reciprocity map of two-dimensional local class field theory identifies this filtration with the ramification filtration.Comment: This is a corrected and extended version of my 1998 Nottingham preprint; many details are added. AmSTeX, 28 pages. To appear in Proceedings of the conference "Ramification theory of arithmetic schemes" (Luminy, 1999

High precision studies of soft dipole mode in two-neutron halo nuclei: 6^{6}He case

The "soft dipole" E1 strength function is calculated for the transition from the $^{6}$He $0^+$ ground state to the $1^-$ continuum $^{4}$He+$n$+$n$. The calculations were performed within the hyperspherical harmonics formalism. The sensitivity of the results to the $^{6}$He ground state structure and to final state interactions, are analyzed. The large-basis calculations show the reliably converged results for soft dipole strength function and for momentum correlations of the ^{6}\mbox{He} \rightarrow \, ^{4}He+$n$+$n$ dissociation products. Transition mechanisms are analyzed based on the momentum correlations. The comparison with experimental data is provided.Comment: 16 pages, 17 figure

Modeling and removal of optical ghosts in the PROBA-3/ASPIICS externally occulted solar coronagraph

Context: ASPIICS is a novel externally occulted solar coronagraph, which will be launched onboard the PROBA-3 mission of the European Space Agency. The external occulter will be placed on the first satellite approximately 150 m ahead of the second satellite that will carry an optical instrument. During 6 hours per orbit, the satellites will fly in a precise formation, constituting a giant externally occulted coronagraph. Large distance between the external occulter and the primary objective will allow observations of the white-light solar corona starting from extremely low heights 1.1RSun. Aims: To analyze influence of optical ghost images formed inside the telescope and develop an algorithm for their removal. Methods: We implement the optical layout of ASPIICS in Zemax and study the ghost behaviour in sequential and non-sequential regimes. We identify sources of the ghost contributions and analyze their geometrical behaviour. Finally we develop a mathematical model and software to calculate ghost images for any given input image. Results: We show that ghost light can be important in the outer part of the field of view, where the coronal signal is weak, since the energy of bright inner corona is redistributed to the outer corona. However the model allows to remove the ghost contribution. Due to a large distance between the external occulter and the primary objective, the primary objective does not produce a significant ghost. The use of the Lyot spot in ASPIICS is not necessary.Comment: 14 pages, 13 figure

Low polarized emission from the core of coronal mass ejections

In white-light coronagraph images, cool prominence material is sometimes observed as bright patches in the core of coronal mass ejections (CMEs). If, as generally assumed, this emission is caused by Thomson-scattered light from the solar surface, it should be strongly polarised tangentially to the solar limb. However, the observations of a CME made with the SECCHI/STEREO coronagraphs on 31 August 2007 show that the emission from these bright core patches is exceptionally low polarised. We used the polarisation ratio method of Moran and Davila (2004) to localise the barycentre of the CME cloud. By analysing the data from both STEREO spacecraft we could resolve the plane-of-the-sky ambiguity this method usually suffers from. Stereoscopic triangulation was used to independently localise the low-polarisation patch relative to the cloud. We demonstrated for the first time that the bright core material is located close to the centre of the CME cloud. We show that the major part of the CME core emission, more than 85% in our case, is H$\alpha$ radiation and only a small fraction is Thomson-scattered light. Recent calculations also imply that the plasma density in the patch is 8 10$^8$ cm$^{-3}$ or more compared to 2.6 10$^6$ cm$^{-3}$ for the Thomson-scattering CME environment surrounding the core material.Comment: 5 pages, 3 figure

Current perpendicular to plane Giant Magnetoresistance (GMR) in laminated nanostructures

We theoretically studied spin dependent electron transport perpendicular-to-plain (CPP) in magnetic laminated multilayered structures by using Kubo formalism. We took into account not only bulk scattering, but the interface resistance due to both specular and diffuse reflection and also spin conserving and spin-flip processes. It was shown that spin-flip scattering at interfaces substantially reduces the value of GMR. This can explain the experimental observations that the CPP GMR ratio for laminated structures only slightly increases as compared to non-laminated ones despite lamination induces a significant increase in CPP resistance.Comment: 4 pages, 2 figure

Analysis of method of polarization surveying of water surface oil pollution

A method of polarization surveying of oil films on the water surface is analyzed. Model calculations of contrasted oil and water obtained with different orientations of the analyzer are discussed. The model depends on the spectral range, water transparency and oil film, and the selection of observational direction

Three-dimensional light bullets in a Bragg medium with carbon nanotubes

We present a theoretical study of the propagation of three-dimensional extremely short electromagnetic pulses (a.k.a. light bullets) through a Bragg medium containing an immersed array of carbon nanotubes. We demonstrate the possible stable propagation of such light bullets. In particular, our results suggest these light bullets can carry information about the Bragg medium itself.Comment: To appear in Appl. Phys.

Observation of the fine structure for rovibronic spectral lines in visible part of emission spectra of D2D_2

For the first time in visible part of the $D_2$ emission spectrum the pseudo doublets representing partly resolved fine structure of rovibronic lines have been observed. They are characterized by splitting values about 0.2 cm$^{-1}$ and relative intensity of the doublet components close to 2.0. It is shown that they are determined by triplet splitting in lower rovibronic levels of various $^3\Lambda_g^\pm \to c^3\Pi_u^-$ electronic transitions. It is proposed to use an existence of such partly resolved fine structure patterns for identification of numerous unassigned spectral lines of the $D_2$ molecule coming from great variety of triplet "gerade" electronic states to vibro-rotational levels of the $c^3\Pi_u^-$ state.Comment: 6 pages, including 2 figures and 1 table; submitted to Phys.Rev.Let