Hybrid AlGaN-SiC Avalanche Photodiode for Deep-UV Photon Detection

The proposed device is capable of counting ultraviolet (UV) photons, is compatible for inclusion into space instruments, and has applications as deep- UV detectors for calibration systems, curing systems, and crack detection. The device is based on a Separate Absorption and Charge Multiplication (SACM) structure. It is based on aluminum gallium nitride (AlGaN) absorber on a silicon carbide APD (avalanche photodiode). The AlGaN layer absorbs incident UV photons and injects photogenerated carriers into an underlying SiC APD that is operated in Geiger mode and provides current multiplication via avalanche breakdown. The solid-state detector is capable of sensing 100-to-365-nanometer wavelength radiation at a flux level as low as 6 photons/pixel/s. Advantages include, visible-light blindness, operation in harsh environments (e.g., high temperatures), deep-UV detection response, high gain, and Geiger mode operation at low voltage. Furthermore, the device can also be designed in array formats, e.g., linear arrays or 2D arrays (micropixels inside a superpixel)

An Evening Sector Ps 6 - Omega Band Event

Article draft. Author list indicative and roughly corresponds to amount of contribution to the article to date.Abstract. Ps 6 magnetic disturbances and associated optical forms known as omega bands are usually associated with the morning sector. Some evidence for similar phenomenology in the evening sector has been presented by Solovyev et al. (1999). We confirm and extend those results with high time resolution magnetic and imaging observations from Athabasca University Geophysical Observatory for an event that took place on July 27, 2003, along with conjugate hemisphere imaging from the Polar spacecraft. The observed signatures indicate sunward drift (westward in the evening sector). Magnetic perturbations feature negative Y and transitional Z indicating westward passage of poleward equivalent currents overhead. As has been suggested by Connors et al. (2003) to be often the case for morning sector Ps 6/omega bands, initiation of the evening sector event coincided with substorm onset. From optical and magnetic data we obtain consistent results for the drift rate of the forms, which changed during the event. An inner magnetospheric source is suggested, with triggering of the onset by an increase in solar wind speed

Development of the Virtual Earth\u27s Magnetosphere System (VEMS)

We have constructed a new research environment for geo-space science based on 3-D visualization tool and network database; Virtual Earth\u27s Magnetosphere System (VEMS). With an interactive research environment researchers can visually understand structures of the Earth\u27s magnetosphere using VEMS. On the VEMS, computer simulation results and observation data are simultaneously visualized, having a potential to data assimilation for geo-space studies in the future. Since the VEMS deals with time-dependent data, it also helps researchers to study dynamics of the Earth\u27s magnetosphere. We found that immersive data analyses are possible using the VEMS on a virtual reality system

Coherent Matter Wave Transport in Speckle Potentials

This article studies multiple scattering of matter waves by a disordered optical potential in two and in three dimensions. We calculate fundamental transport quantities such as the scattering mean free path $\ell_s$, the Boltzmann transport mean free path \elltrb, and the Boltzmann diffusion constant $D_B$, using a diagrammatic Green functions approach. Coherent multiple scattering induces interference corrections known as weak localization which entail a reduced diffusion constant. We derive the corresponding expressions for matter wave transport in an correlated speckle potential and provide the relevant parameter values for a possible experimental study of this coherent transport regime, including the critical crossover to the regime of strong or Anderson localization.Comment: 33 pages, minor corrections, published versio

Stills of the Polar Visible Aurora from July 16, 2000

Polar Visible Aurora from July 16, 2000 Educational levels: Undergraduate lower division, Undergraduate upper division, Graduate or professional

Polar Visible Aurora Animation: July 15, 2000

An animation of the visible aurora in the northern hemisphere on July 15, 2000 as measured by Polar Educational levels: Undergraduate lower division, Undergraduate upper division, Graduate or professional

Polar Visible Aurora Animation: July 13, 2000

An animation of the visible aurora in the northern hemisphere on July 13, 2000 as measured by Polar Educational levels: Undergraduate lower division, Undergraduate upper division, Graduate or professional

Stills of the Polar Visible Aurora from October 22, 1999

Polar Visible Aurora from October 22, 1999 Educational levels: Undergraduate lower division, Undergraduate upper division, Graduate or professional

Polar Visible Aurora Animation: July 15, 2000 to July 16, 2000

An animation of the visible aurora in the northern hemisphere from July 15, 2000 to July 16, 2000 as measured by Polar Educational levels: Undergraduate lower division, Undergraduate upper division, Graduate or professional

Geomagnetic Storm: November 2003

Coronal Mass Ejections from sunspot 10484 sweep by the Earth on November 20, 2003, generating aurora displays worldwide. This view is from the Polar spacecraft with a false-color data overlaid on the Earths surface. Red marks the highest intensity, blue the lowest. Educational levels: Undergraduate lower division, Undergraduate upper division, Graduate or professional