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This work presents the design and validation of a vibrating coil magnetometer for the characterization of the field dependence of the critical current density of centimeter-sized bulk superconductors as an alternative to the destructive methods typically used. The magnetometer is also shown to be capable of measuring the magnetic moment in an applied field of up to 5 T for diverse magnetic materials, such as soft and hard ferromagnets and high-temperature superconducting pellets. The vibrating coil magnetometer was first optimized using finite element simulations and calibrated using a commercial vibrating sample magnetometer. The vibrating coil magnetometer was benchmarked with hysteresis measurements of a Nd2Fe14B disk made with a commercial hysteresisgraph, showing good agreement between the different setups. The magnetic hysteresis of a YBa2Cu3O7−x superconducting pellet was measured at 77 K, showing a penetration field of 1 T and an irreversibility field of 4 T. The field dependent critical current density of the superconductor was then inferred from the magnetic hysteresis measurements and extrapolated at low fields. Finally, the resulting critical current density was used to successfully reproduce the measured magnetization curve of the pellet at 2 T with finite element simulations. [ABSTRACT FROM AUTHOR]

The Planck High Frequency Instrument (HFI) surveyed the sky continuously from August 2009 to January 2012. Its noise and sensitivity performance were excellent (from 11 to 40 aWHz-1), but the rate of cosmic-ray impacts on the HFI detectors was unexpectedly higher than in other instruments. Furthermore, collisions of cosmic rays with the focal plane produced transient signals in the data (glitches) with a wide range of characteristics and a rate of about one glitch per second. A study of cosmic-ray impacts on the HFI detector modules has been undertaken to categorize and characterize the glitches, to correct the HFI time-ordered data, and understand the residual effects on Planck maps and data products. This paper evaluates the physical origins of glitches observed by the HFI detectors. To better understand the glitches observed by HFI in flight, several ground-based experiments were conducted with flight-spare HFI bolometer modules. The experiments were conducted between 2010 and 2013 with HFI test bolometers in different configurations using varying particles and impact energies. The bolometer modules were exposed to 23 MeV protons from the Orsay IPN Tandem accelerator, and to 241Am and 244Cm α-particle and 55Fe radioactive X-ray sources. The calibration data from the HFI ground-based preflight tests were used to further characterize the glitches and compare glitch rates with statistical expectations under laboratory conditions. Test results provide strong evidence that the dominant family of glitches observed in flight are due to cosmic-ray absorption by the silicon die substrate on which the HFI detectors reside. Glitch energy is propagated to the thermistor by ballistic phonons, while thermal diffusion also contributes. The average ratio between the energy absorbed, per glitch, in the silicon die and that absorbed in the bolometer is equal to 650. We discuss the implications of these results for future satellite missions, especially those in the far-infrared to submillimeter and millimeter regions of the electromagnetic spectrum. [ABSTRACT FROM AUTHOR]

Abstract: Smart windows offer an opportunity to reduce energy consumption. However, the use of multiple optical elements, such as low emittance coatings and electrochromic devices, is detrimental to the luminous transmittance of these high performance windows. Although the addition of antireflective coatings has helped to reduce this problem, some elements, such as high index of refraction materials still give rise to loss of light. We show that replacing the single WO3 active coating, the main component of an electrochromic device, by an appropriately designed electrochromic interference filter can significantly increase the transmittance. This active filter is based on a stack of dense and porous WO3 layers. We first study the effect of porosity on the physical and electrochromic properties of WO3 prepared by radio frequency magnetron sputtering. We demonstrate that the overlying dense coating does not inhibit the coloration of the underlying porous coating. The best performing films are combined into a 27 layer quarter-wave interference filter which is shown to cycle between bleached and colored states, while providing attractive transmission. Finally, we discuss various filter designs which can increase the transmission of an electrochromic device in its bleached state, as well as the potential use of active filters for optical security devices possessing two levels of authentication. [ABSTRACT FROM AUTHOR]

Abstract: Gold nanoparticles embedded in a dielectric matrix (SiO2) were prepared by a hybrid technique combining plasma-enhanced chemical vapor deposition and pulsed DC sputtering. The concentration and spatial distribution of the metal particles were controlled by deposition parameters, while particle size and size distribution were further adjusted by annealing. Subsequently, the nanocomposite samples were exposed to an energetic ion beam (30 MeV), a treatment that has been shown to transform spherical particles to high aspect ratio ellipsoids. The films were studied in detail by spectroscopic ellipsometry and spectrophotometry, and their optical response was correlated with their microstructural features such as particle alignment in the ion beam direction, as documented by the blue shift of the surface plasmon resonance (SPR). We show that such process is reversible in a sense that subsequent annealing of ion beam-irradiated particles red shifts the SPR to the initial position. [Copyright &y& Elsevier]

Submillimetre maps of NGC 891 have been obtained with the Programme National d'bservations Submillimétriques (PRONAOS) balloon-borne telescope and with the Infrared Space Observatory Photopolarimeter (ISOPHOT) on board the ISO satellite. In this article, we also gather data from the Infrared Astronomical Satellite (IRAS) and the Submillimetre Common-User Bolometer Array (SCUBA) to present the complete submillimetre spectrum of this nearby edge-on spiral galaxy. We derive submillimetre emission profiles along the major axis. The modified blackbody fits, assuming a single dust component, lead to temperatures of 19-24 K towards the centre and 18-20 K towards the edges, with possible variations in the dust spectral index from 1.4 to 2. The two-component fits lead to a warm-component temperature of 29 K all along the galaxy, with a cold component at 16 K. The interstellar medium (ISM) masses derived by these two methods are quite different: 4.6 × 10[SUP9] M[SUB⊙] in the case of the one-component model and 12 × 10[SUP9] M[SUB⊙] in the case of the two-component one. This two-component fit indicates that the cold dust to warm dust ratio is between 20 and 40, the highest values being in the wings of this galaxy. Compared to dust mass estimates, both estimates of the ISM mass are consistent with a gas to dust mass ratio of 240, which is close to the Milky Way value. Our results illustrate the importance of accurate submillimetre spectra in deriving masses of the ISM in galaxies. [ABSTRACT FROM AUTHOR]

We report the results of a joint analysis of data from BICEP2/Keck Array and Planck. BICEP2 and Keck Array have observed the same approximately 400 deg2 patch of sky centered on RA 0h, Dec. −57.5deg. The combined maps reach a depth of 57 nK deg in Stokes Q and U in a band centered at 150 GHz. Planck has observed the full sky in polarization at seven frequencies from 30 to 353 GHz, but much less deeply in any given region (1.2 μK deg in Q and U at 143 GHz). We detect 150×353 cross-correlation in B-modes at high significance. We fit the single- and cross-frequency power spectra at frequencies ≥150 GHz to a lensed-ΛCDM model that includes dust and a possible contribution from inflationary gravitational waves (as parameterized by the tensor-to-scalar ratio r), using a prior on the frequency spectral behavior of polarized dust emission from previous \planck\ analysis of other regions of the sky. We find strong evidence for dust and no statistically significant evidence for tensor modes. We probe various model variations and extensions, including adding a synchrotron component in combination with lower frequency data, and find that these make little difference to the r constraint. Finally we present an alternative analysis which is similar to a map-based cleaning of the dust contribution, and show that this gives similar constraints. The final result is expressed as a likelihood curve for r, and yields an upper limit r0.05<0.12 at 95% confidence. Marginalizing over dust and r, lensing B-modes are detected at 7.0σ significance., Astronomy

Deals with the scanning strategies for the Planck mission of the European Space Agency using the Low Frequency Instrument and High Frequency Instrument surveyor. Requirements that should be met by the strategy; Investigation of the reprojection of scan-synchronous systematic effects on final maps of the sky.