Спектральный состав отражённой и проникающей в глубь снежного покрова коротковолновой радиации в районе посёлка Баренцбург (Шпицберген)

Data on spectral composition of shortwave radiation that is reflected from snow and penetrates deep into the snow cover obtained near the Barentsburg settlement (Svalbard) are discussed in the paper. Measurements were made by the use of the spectral radiometer TriOS Ramses within the wavelength range of 280–950 nm. The results will allow more proper taking account of the anthropogenic pollution effects on the radiative properties of snow cover under conditions of industrial activity related to the coal extraction and burning in Barentsburg.Представлены результаты измерений спектрального состава отражённой от снежной поверхности и проникающей в глубь коротковолновой радиации. Измерения выполнены с помощью спектрального радиометра TriOS Ramses в диапазоне длин волн 280–950 нм. Результаты измерений позволят корректнее учитывать влияние антропогенного загрязнения на радиационные свойства снежного покрова в условиях хозяйственной деятельности, связанной с добычей и сжиганием угля в посёлке Баренцбург

Low-frequency voltage noise and electrical transport in (100)-tilt YBa2Cu3O7-x grain-boundary junctions

We have fabricated [100]-tilt YBa2Cu3O7-x grain-boundary junctions with high characteristic voltages IcRn and studied their low-frequency voltage noise. The intensities of normalized resistance and critical current fluctuations have been found to be equal in these junctions and a complete antiphase correlation between these two fluctuations has been demonstrated. These results show that quasiparticles and Cooper pairs in the [100]-tilt junctions tunnel directly through the same parts of the barrier. The band-bending model with charge fluctuations at the structural interface is indicated to be adequate for understanding current transport and voltage noise in high-T-c grain-boundary junctions. (c) 2006 American Institute of Physics

Spectral range of the ac Josephson effect in (001)-tilt YBa2Cu3O7-x bicrystal junctions

We have studied the ac Josephson effect in YBa2Cu3O7-x bicrystal junction by monitoring the voltage dependence of the dc current response DeltaI(V) induced by low-power monochromatic radiation with the frequencies f(i). The intensity of odd-symmetric resonances in the function DeltaI(V) near the voltages V-i = hf(i)/2e is proportional to the amplitude of Josephson oscillations at the frequency f(i). The resonance intensities have been mapped as a function of the Josephson frequency f(i) in the range from 5 GHz to 5 THz, the junction resistance R-n in the range from 0.4 to 80 Ohm and junction characteristic voltages IcRn in the range from 5 muV to 1.8 mV. The central frequency of the range was scaled with the IcRn-product of the junction and it could be shifted from GHz-range to the THz-range by a temperature decrease. The spectral range was limited by an enhanced noise broadening of the Josephson linewidth at low frequencies and by increased dc Joule heating at high frequencies