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The photometry of eclipse white-light (W-L) images showing a moving blob is interpreted for the first time together with observations from space with the PRoject for On Board Autonomy (PROBA-2) mission (ESA). An off-limb event seen with great details in W-L was analyzed with the SWAP imager (Sun Watcher using Active pixel system detector and image Processing) working in the EUV near 174 A. It is an elongated plasma blob structure of 25 Mm diameter moving above the E-limb with coronal loops under. Summed and co-aligned SWAP images are evaluated using a 20 hours sequence, in addition to the July 11, 2010 eclipse W-L images taken from several sites. The Atmospheric Imaging Assembly (AIA) instruments on board the Solar Dynamical Observatory (SDO) recorded the event suggesting a magnetic reconnection near a high neutral point; accordingly, we also call it a magnetic plasmoid. The measured proper motion of the blob shows a velocity up to 12 km s^-1. Electron densities of the isolated condensation (cloud or blob or plasmoid) is photometrically evaluated. The typical value is 10^8 cm^-3 at r=1.7 R, superposed on a background corona of 10^7 cm^-3 density. The mass of the cloud near its maximum brightness is found to be 1.6x10^13 gr which is typically 0.6x10^-4 of the overall mass of the corona. From the extrapolated magnetic field the cloud evolves inside a rather broad open region but decelerates, after reaching its maximum brightness. The influence of such small events for supplying material to the ubiquitous slow wind is noticed. A precise evaluation of the EUV photometric data after accurately removing the stray light, suggests an interpretation of the weak 174 A radiation of the cloud as due to resonance scattering in the Fe IX/X lines., Comment: 17 pages, 11 figures, Accepted in Solar Physics

Using determinant quantum Monte Carlo (DQMC) simulations, we systematically study the doping dependence of the crossover from one to two dimensions and its impact on the magnetic properties of the Hubbard model. A square lattice of chains is used, in which the dimensionality can be tuned by varying the interchain coupling $t_\perp$. The dynamical spin structure factor and static quantities, such as the static spin susceptibility and nearest-neighbor spin correlation function, are characterized in the one- and two-dimensional limits as a benchmark. When the dimensionality is tuned between these limits, the magnetic properties, while evolving smoothly from one to two dimensions, drastically change regardless of the doping level. This suggests that the spin excitations in the two-dimensional Hubbard model, even in the heavily doped case, cannot be explained using the spinon picture known from one dimension. The DQMC calculations are complemented by cluster perturbation theory studies to form a more complete picture of how the crossover occurs as a function of doping and how doped holes impact magnetic order., Comment: 14 pages, 9 figures

We present some new accurate CCD photometry analysis of the white light solar corona at the time of the last 20 March 2015 total eclipse (airborne observations on a Falcon 7X and at ground-based Svalbard). We measured coronal brightness profiles taken along radial directions from 1.001 to 3 solar radii in the northern, southern and equatorial regions, after removing the F corona and the sky background. These studies allow to evaluate the density gradients, structures and temperature heterogeneity, by considering the Thomson scattering in white light of the K corona and also emissions of the EUV Fe XII 193A (1 to 2 MK) and Fe XI 171/174 (lower temperature) simultaneously observed by SDO/AIA and SWAP Proba2 space missions. Some dispersion between the regions is noticed. The limitation of the hydrostatic equilibrium assumption in the solar atmosphere is discussed as well as the contribution of the magnetic field pressure gradients as illustrated by a comparison with the model stationary magnetic corona from Predictive Sc. Inc. These results are compared with the results of the quieter 2010 total solar eclipse corona analyzed with the same method. This photometric analysis of the inner and intermediate white light corona will contribute to the preparation of the Aspiics/Proba 3 flying formation future coronagraphic mission of ESA for new investigation at time of artificial eclipses produced in Space. Note that Aspiics will also observe in the He I D3 line at 5876 A, and will record intensities of the Fe XIV line 5303A simultaneously with the analysis of the orange white- light continuum, including precise polarimetry analysis., Comment: 4 pages, 4 figures, proceedings of the SF2A meeting, June 2015, in the session "Phenom\`enes dynamiques et atmosph\'eriques, plasmas spatiaux"

SWAP images from PROBA2 taken at 174 {\AA} in the Fe IX/X lines are compared with simultaneous slitless flash spectra obtained during the solar total eclipse of 11 July, 2010. Myriads of faint low excitation emission lines together with the He I and He II Paschen {\alpha} chromospheric lines are recorded on eclipse spectra where regions of limb prominences are obtained with space-borne imagers. We analyzed a deep flash spectrum obtained by summing 80 individual spectra to evaluate the intensity modulations of the continuum. Intensity deficits are observed and measured at the prominences boundaries in both eclipse and SWAP images. The prominence cavities interpreted as a relative depression of plasma density, produced inside the corona surrounding the prominences, and some intense heating occurring in these regions, are discussed. Photometric measurements are shown at different scales and different, spectrally narrow, intervals for both the prominences and the coronal background., Comment: 24 pages, 15 figures. arXiv admin note: substantial text overlap with arXiv:1205.1325

Images from the SWAP (Proba 2 mission) taken at 174A in the Fe IX/X lines are compared to simultaneous slitless flash spectra taken during the last solar total eclipse of July, 11th 2010. Many faint low excitation emission lines together with the HeI and HeII Paschen Alpha chromospheric lines are recorded on eclipse spectra where regions of limb prominences are obtained with space-borne imagers. We consider a deep flash spectrum obtained by summing 80 individual spectra to show the intensity modulations of the continuum. Intensity depressions are observed around the prominences in both eclipse and SWAP images. The prominence cavities are interpreted as a relative depression of plasma density, produced inside the corona surrounding the prominences. Photometric measurements are shown at different scales and different, spectrally narrow, intervals for both the prominences and the coronal background., Comment: 22 pages, 14 figures, accepted to publish in Sol. Phys

Electrodeposited thin film cells have been fabricated with record-breaking efficiencies of 11.4%. This presentation examines conversion mechanisms in cells with a focus on the effect of CdS buffer layers using a range of complementary tools. Dark currents (IVs) are well described by series and parallel resistances, and two dominant recombination mechanisms represented by parallel diodes. Measurements of IV as a function of temperature (IVT) allow extraction of activation energies corresponding to these processes and indicate their spatial position. Admittance spectroscopy (AS) gives an independent estimate of the same energies, and yields values of the defect densities of states in the forbidden gap. Two dominant levels are apparent, confirming the validity of the IV analysis. Spectral response (QE) measurements are presented, yielding information on minority carrier collection efficiency. The different methods of parameter extraction are correlated and indicate recombination levels some hundreds of meV above the valence band and below the conduction band. Bias dependence of admittance spectroscopy gives indications on the localisation of defect centres with one defect situated at the CdS heterointerface and the other in the bulk of the depletion region. The dark current analysis indicates that photogenerated minority carrier collection is the limiting factor in these cells at the operating bias., Comment: Preprint for submission to the 20th EUPVSEC, Barcelona, Spain, 2005, 4 pages pp. 1851 - 1854