4H-SiC Schottky diode arrays for X-ray detection

Five SiC Schottky photodiodes for X-ray detection have been electrically characterized at room temperature. One representative diode was also electrically characterized over the temperature range 20°C to 140 °C. The performance at 30 °C of all five X-ray detectors, in both current mode and for photon counting X-ray spectroscopy was investigated. The diodes were fabricated in an array form such that they could be operated as either a 2×2 or 1×3 pixel array. Although the devices showed double barrier heights, high ideality factors and higher than expected leakage current at room temperature (12 nA/cm2 at an internal electric field of 105 kV/ cm), they operated as spectroscopic photon counting soft X-ray detectors uncooled at 30 °C. The measured energy resolution (FWHM at 17.4 keV, Mo Kα) varied from 1.36 to 1.68 keV among different diodes

First experimental results obtained using the highpower free electron laser at the siberian center for photochemical research

The first lasing near the wavelength of 140 µm was achieved in April 2003 using a high-power free electron laser (FEL) constructed at the Siberian Center for Photochemical Research. In this paper we briefly describe the design of the FEL driven by an accelerator–recuperator. Characteristics of the electron beam and terahertz laser radiation, obtained in the first experiments, are also presented in the paper.У Сибірському центрі фотохімічних досліджень навесні 2003 року отримана генерація випромінювання з довжиною хвилі 140 мкм на потужному лазері на вільних електронах (ЛВЕ). У роботі коротко описана конструкція ЛВЕ на базі прискорювача рекуператора і представлені результати вимірювання деяких параметрів електронного пучка і терагерцового випромінювання.В Сибирском центре фотохимических исследований весной 2003 года получена генерация излучения с длиной волны 140 мкм на мощном лазере на свободных электронах (ЛСЭ). В работе кратко описана конструкция ЛСЭ на базе ускорителя рекуператора и представлены результаты измерения некоторых параметров электронного пучка и терагерцового излучения

Climate and biotic evolution during the Permian-Triassic transition in the temperate Northern Hemisphere, Kuznetsk Basin, Siberia, Russia

The Siberian Traps volcanism is widely considered the main cause of the end-Permian mass extinction, the greatest biological crisis in the Earth history. While the extinction is interpreted as catastrophic and sudden with estimates of duration of approximately 35–40 thousand years from marine strata in South China, various lines of evidence have emerged for a more complex, prolonged, and diachronous extinction pattern. We present here the results of a multidisciplinary study of the Permian-Triassic continental transition in the Kuznetsk Basin, Russia. The region is proximal to the Siberian Traps LIP and the detrimental effects of the flood basalt volcanism in the Kuznetsk Basin may have been of similar scale as in the main area of the Siberian Traps distribution (Tunguska and Taymyr regions). Whereas earlier work has placed the Permian-Triassic boundary position between the coal-bearing Tailugan Formation and the volcanoclastic Maltsev Formation, here we revised the traditional model using three independent methods: radioisotopic CA-IDTIMS U-Pb zircon ages, δ13Corg isotope values and paleomagnetic proxies. The regional extinction of the humid-dominated forest flora (cordaites) and the aridity-induced biotic turnover in the Kuznetsk Basin occurred 820 kyr earlier than the end-Permian extinction event recorded in South China at 251.94 Ma. The biota in Kuznetsk Basin at the turnover subsequently diversified (with some exceptions) across the Permian-Triassic transition. By compiling a large taxonomic database, we find that marine and terrestrial biotic diversity in Siberia progressively increased from the beginning of the Permian up to the middle Roadian (early Guadalupian global glacial event). After that time, the diversity at the species and generic level progressively and slowly declined towards the aforementioned latest Changhsingian (252.76 Ma) biotic turnover. Starting from this time, the biota rapidly diversified in the latest Changhsingian and Early-Middle Triassic. We suggest that the Permian-Triassic mass extinction mostly occurred in the tropics and subtropics due to the strong climatic warming, which was relatively low in late Changhsingian and gradually but quickly extends in the latest Changhsingian to an abnormally high temperature and extremely low oxygenated water in the oceans that was deadly for most marine animals. The warm climate shift poleward during Permian-Triassic transition in the middle-high latitudes caused the replacement (turnover) of the humid-related biotas by the dry climate-related and more diverse communities, which continued to expand throughout the Triassic in both marine and terrestrial habitats. The pattern of the Permian-Triassic event in both marine and terrestrial habitats was more intricate in terms of extinction, turnover, and diversity of biota within the different climatic zones and environmental habitats than has been generally considered