The Giant Radio Array for Neutrino Detection (GRAND) Project

The GRAND project aims to detect ultra-high-energy neutrinos, cosmic rays and gamma rays, with an array of 200,000 radio antennas over 200,000km$^2$, split into ∼20 sub-arrays of ∼10,000km$^2$ deployed worldwide. The strategy of GRAND is to detect air showers above 10$^{17}$eV that are induced by the interaction of ultra-high-energy particles in the atmosphere or in the Earth crust, through its associated coherent radio-emission in the 50−200MHz range. In its final configuration, GRAND plans to reach a neutrino-sensitivity of ∼10$^{−10}$GeV cm$^{−2}$s$^{−1}$sr$^{−1}$ above 5×10$^{17}$eV combined with a sub-degree angular resolution. GRANDProto300, the 300-antenna pathfinder array, is planned to start data-taking in 2021. It aims at demonstrating autonomous radio detection of inclined air-showers, and study cosmic rays around the transition between Galactic and extra-Galactic sources. We present preliminary designs and simulation results, plans for the ongoing, staged approach to construction, and the rich research program made possible by the proposed sensitivity and angular resolution

The Giant Radio Array for Neutrino Detection (GRAND) Project

The GRAND project aims to detect ultra-high-energy neutrinos, cosmic rays and gamma rays, with an array of 200,000 radio antennas over 200,000km$^2$, split into ∼20 sub-arrays of ∼10,000km$^2$ deployed worldwide. The strategy of GRAND is to detect air showers above 10$^{17}$\,eV that are induced by the interaction of ultra-high-energy particles in the atmosphere or in the Earth crust, through its associated coherent radio-emission in the 50−200\,MHz range. In its final configuration, GRAND plans to reach a neutrino-sensitivity of ∼10$^{−10}$GeVcm$^{−2}$s$^{−1}$sr$^{−1}$ above 5×10$^{17}$\,eV combined with a sub-degree angular resolution. GRANDProto300, the 300-antenna pathfinder array, is planned to start data-taking in 2021. It aims at demonstrating autonomous radio detection of inclined air-showers, and study cosmic rays around the transition between Galactic and extra-Galactic sources. We present preliminary designs and simulation results, plans for the ongoing, staged approach to construction, and the rich research program made possible by the proposed sensitivity and angular resolution

Self-trigger radio prototype array for GRAND

The GRANDProto300 (GP300) array is a pathfinder for the Giant Radio Array for Neutrino Detection (GRAND) project. The deployment of the array, consisting of 300 antennas, will start in 2021 in a radio-quiet area of ~200 km2 near Lenghu (~3000 m a.s.l.) in China. Serving as a test bench, the GP300 array is expected to pioneer techniques of autonomous radio detection including identification and reconstruction of nearly horizontal cosmic-ray (CR) air showers. In addition, the GP300 array is at a privileged position to study the transition between Galactic and extragalactic origins of cosmic rays, due to its large effective area and the precise measurements of both energy and mass composition for CRs with energies ranging from 30 PeV to 1 EeV. Using the GP300 array we will also investigate the potential sensitivity for radio transients such as Giant Radio Pulses and Fast Radio Bursts in the 50-200 MHz range

The Solar Eclipse of 2006 and the Origin of Raylike Features in the White-Light Corona

International audienceSolar eclipse observations have long suggested that the white-light corona is permeated by long fine rays. By comparing photographs of the 2006 March 29 total eclipse with current-free extrapolations of photospheric field measurements and with images from the Solar and Heliospheric Observatory (SOHO), we deduce that the bulk of these linear features fall into three categories: (1) polar and low-latitude plumes that overlie small magnetic bipoles inside coronal holes, (2) helmet streamer rays that overlie large loop arcades and separate coronal holes of opposite polarity, and (3) ``pseudostreamer'' rays that overlie twin loop arcades and separate coronal holes of the same polarity. The helmet streamer rays extend outward to form the plasma sheet component of the slow solar wind, while the plumes and pseudostreamers contribute to the fast solar wind. In all three cases, the rays are formed by magnetic reconnection between closed coronal loops and adjacent open field lines. Although seemingly ubiquitous when seen projected against the sky plane, the rays are in fact rooted inside or along the boundaries of coronal holes

Local Observation and Spectroscopy of Optical Modes in Active Photonic Crystal Microcavity

We report the direct, room-temperature, near-field mapping and spectroscopy of the optical modes of a photonic-crystal microcavity containing quantum wells. We use a near-field optical probe to reveal the imprint of the cavity mode structure on the quantum-well emission. Furthermore, near-field spectroscopy allows us to demonstrate the strong spatial and spectral dependence of the coupling between the sources and the microcavity. This knowledge will be essential in devising future nanophotonic devices

ECLIPSE 2017: NEW RESULTS ON THE DYNAMICAL INNER-CORONA

The total solar eclipse of 21 Aug. 2017 was observed by our teams in excellent conditions for almost 1 hour (from Oregon at 17h12, Idaho 17h27, see Fig. 1, Wyoming 17h36 and Missouri, 18h12 U.T.). Excellent images were recorded in white-light (W-L), including a very high spatial-temporal resolution (HR) sequence covering faint dynamical phenomena related to an exceptionally slow CME that evolved over the E-limb. In addition: i) The overall polarized K-corona, from linearly polarized images taken in 12 positions with a green filter, was analyzed, to be compared to the latest quantitative magnetic dynamical coronal modeling of the Mikic team (Mikić et al. 2018). The complex fine scale structure reflecting the magnetic field topology is analyzed using specially designed algorithms with suggestion of a more turbulent field in the outer corona above r= 2Rs. ii) The more simple Polar-cap Regions are considered to compare the impressive fine-scale more linear W-L plumes with the EUV plumes simultaneously observed in the lower corona with the AIA filtergrams of the SDO mission; we integrate 60 successive AIA images taken with the 171, 193, 211 Å filters to improve the S/N ratio of EUV frames. The new view of dynamical polar plumes is illustrated at different temperature regimes, including a high temperature regime. Some evidence of fast propagating transverse waves is obtained by comparing deep spatially Fourier-filtered W-L images of plumes and jets separated by typically 1 min of time; amplitudes are larger for larger radial distances, suggesting that they reflect the propagation of alfvenic disturbances and possibly their dissipation. iii) The most notable dynamic phenomenon is analyzed at the E-limb: it is a slow CME that shows a constant 250 km/s velocity from the LASCO (SoHO) observations. It is analyzed here in W-L with HR eclipse images and with images from the SECCHI EUV filtergrams of the STEREO mission and from the AIA of the SDO mission. Very small scale and faint moving and curved W-L features at r= 1.7 Rs, possibly owning to high disrupted loops, are analyzed for the 1st time with a 20 sec temporal resolution movie; falling back remnants of the erupted high latitude polar crown filament-prominence found at the feet of the CME are detected in W-L, well after the eruption. It is suggested that such processes are a component of the slow wind that is more easily demonstrated at time of this minimum corona using eclipse images in the r = 1.5 to 2 Rs region where instabilities grow and outwardly propagate.(Boulade et al. (1997) Tavabi et al. (2018

Plasmoid Ejection at a Solar Total Eclipse

The existence of coronal plasmoids has been postulated for many years in order to supply material to streamers and possibly to the solar wind (SW). The W-L SoHO C2 Lasco coronagraph observations were made under the 2.2 solar radii (R0) occulting disk to look at the ultimate sources of the SW; EUV imagers are preferably devoted to the analysis of the corona on and very near the solar disk. Here, in addition to eclipse white-light (W-L) snapshots, we used the new SWAP space-borne imager designed for the systematic survey of coronal activity in the EUV lines near 17.4 nm, over a field of view (FOV) up to 2 R0. Using summed and co-aligned images, the corona can then be evaluated for the 1st time up to the limit of this FOV. At the time of the July 11, 2010, solar total eclipse a 20h continuous run of observations was collected, including images taken during eclipse totality from several ground observing locations where W-L data were collected. A plasmoid-like off-limb event was followed using the SWAP summe

Preliminary results from the March 29, 2006 total eclipse observations in Egypt

International audienc