Investigating seasonal features of electron temperature enhancement regions in the subauroral ionosphere

The electron temperature enhancement is known to occur in the main ionospheric trough during geomagnetic disturbances. In this paper, we study fea-tures of the formation of the electron temperature (Te) enhancement in the subauroral ionosphere by comparing results of the numerical simulation with measurements of Te onboard the CHAMP satellite under moderate geomagnetic activity conditions. It is shown that depending on the terminator position and universal time (UT), the location of the enhanced Te regions in the subauroral ionosphere varies in different seasons. So, in winter ring-shaped and sickle-shaped regions can be formed, whereas during the equinox and summer periods sickle-shaped regions of different lengths and clarity are generally observed

The optical module of the Baikal deep underwater neutrino telescope

A deep underwater Cherenkov telescope has been operating since 1993 in stages of growing size at 1.1 km depth in Lake Baikal. The key component of the telescope is the Optical Module (OM) which houses the highly sensitive phototube QUASAR-370. We describe design and parameters of the QUASAR-370, the layout of the optical module, the front-end electronics and the calibration procedures, and present selected results from the five-year operation underwater. Also, future developments with respect to a telescope consisting from several thousand OMs are discussed.Comment: 30 pages, 24 figure

Modeling the influence of magnetospheric heat fluxes on the electron temperature in the subauroral ionosphere

We present results of modeling of the electron temperature distribution in the F region of the subauroral ionosphere for different helio-geomagnetic conditions with consideration for magnetospheric heat fluxes. It is shown that under quiet geomagnetic condi-tions during a winter period in the dawn and dusk sec-tors “hot” zones with a higher electron temperature are formed, and under disturbed geomagnetic conditions an annular “hot” region is formed in a time interval 04–06 UT as a result of heat inflow from Earth’s magnetosphere along magnetic field lines. The analysis of the DE-2 satellite data demonstrates that such zones can be formed during geomagnetic disturbances

Modeling the electron temperature distribution in F2 region of high-latitude ionosphere for winter solstice conditions

Using the three-dimensional model of the high-latitude ionosphere in Euler variables, which takes into account the mismatch between geographic and geomagnetic poles, we study the behavior of the electron temperature Te in the F2 region as a function of universal time. We present results of the numerical modeling of spatial-temporal distribution of electron temperature in the F2 region for winter solstice, minimum solar activity, and moderate geomagnetic activity. The electron temperature distribution in the F2 region of the high-latitude ionosphere in winter is shown to be characterized by a Te increase in dawn and dusk sectors. Further, the mismatch between the poles leads to regular longitudinal features in Te distribution during Earth’s daily rotation. Thus, at 05 UT, when the Eastern Hemisphere is illuminated, the elevated Te zone is formed only in the dawn sector, and at 17 UT, when the Western Hemisphere is illuminated such zones are observed in both the sectors. We discuss reasons for the formation of the regions with elevated electron temperature depending on the universal time. Results of numerical experiments are compared with similar results obtained with other models

Energy Relaxtation and Hot Spot Formation in Superconducting Single Photon Detectors SSPDS

We have studied the mechanism of energy relaxation and resistive state formation after absorption of a single photon for different wavelengths and materials of single photon detectors. Our results are in good agreement with the hot spot model

Energy Relaxtation and Hot Spot Formation in Superconducting Single Photon Detectors SSPDS

We have studied the mechanism of energy relaxation and resistive state formation after absorption of a single photon for different wavelengths and materials of single photon detectors. Our results are in good agreement with the hot spot model

Response of Graphene Based Gated Nanodevices Exposed to THz Radiation

In this work we report on the response of asymmetric graphene based devices to subterahertz and terahertz radiation. Our devices are made in a configuration of a field-effect transistor with conduction channel between the source and drain electrodes formed with a CVD-grown graphene. The radiation is coupled through a spiral antenna to source and top gate electrodes. Room temperature responsivity of our devices is close to the values that are attractive for commercial applications. Further optimization of the device configuration may result in appearance of novel terahertz radiation detectors