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| 2. |
- Ahrens, J., et al.
(author)
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Measurement of the cosmic ray composition at the knee with the SPASE-2/AMANDA-B10 detectors
- 2004
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In: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 21:6, s. 565-581
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Journal article (peer-reviewed)abstract
- The mass composition of high-energy cosmic rays at energies above 1015 eV can provide crucial information for the understanding of their origin. Air showers were measured simultaneously with the SPASE-2 air shower array and the AMANDA-B10 Cherenkov telescope at the South Pole. This combination has the advantage to sample almost all high-energy shower muons and is thus a new approach to the determination of the cosmic ray composition. The change in the cosmic ray mass composition was measured versus existing data from direct measurements at low energies. Our data show an increase of the mean log atomic mass 〈lnA〉 by about 0.8 between 500 TeV and 5 PeV. This trend of an increasing mass through the "knee" region is robust against a variety of systematic effects. © 2004 Elsevier B.V. All rights reserved.
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| 3. |
- Ahrens, J., et al.
(author)
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Calibration and survey of AMANDA with the SPASE detectors
- 2004
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In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 522:3, s. 347-359
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Journal article (peer-reviewed)abstract
- We report on the analysis of air showers observed in coincidence by the Antarctic Muon and Neutrino detector array (AMANDA-B10) and the South Pole Air Shower Experiment (SPASE-1 and SPASE-2). We discuss the use of coincident events for calibration and survey of the deep AMANDA detector as well as the response of AMANDA to muon bundles. This analysis uses data taken during 1997 when both SPASE-1 and SPASE-2 were in operation to provide a stereo view of AMANDA. © 2003 Elsevier B.V. All rights reserved.
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| 4. |
- Llewellyn, E.J., et al.
(author)
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The OSIRIS Instrument on the Odin Spacecraft
- 2004
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In: Canadian Journal of Physics. - 0008-4204 .- 1208-6045. ; 82:6, s. 411-422
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Journal article (peer-reviewed)abstract
- The optical spectrograph and infrared imager system (OSIRIS) on board the Odin spacecraft is designed to retrieve altitude profiles of terrestrial atmospheric minor species by observing limb-radiance profiles. The grating optical spectrograph (OS) obtains spectra of scattered sunlight over the range 280-800 nm with a spectral resolution of approximately 1 nm. The Odin spacecraft performs a repetitive vertical limb scan to sweep the OS 1 km vertical field of view over selected altitude ranges from approximately 10 to 100 km. The terrestrial absorption features that are superimposed on the scattered solar spectrum are monitored to derive the minor species altitude profiles. The spectrograph also detects the airglow, which can be used to study the mesosphere and lower thermosphere. The other part of OSIRIS is a three-channel infrared imager (IRI) that uses linear array detectors to image the vertical limb radiance over an altitude range of approximately 100 km. The IRI observes both scattered sunlight and the airglow emissions from the oxygen infrared atmospheric band at 1.27 mum and the OH (3-1) Meinel band at 1.53 mum. A tomographic inversion technique is used with a series of these vertical images to derive the two-dimensional distribution of the emissions within the orbit plane.
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| 5. |
- Petelina, S., et al.
(author)
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Comparison of the Odin/OSIRIS stratospheric ozone profiles with coincident POAM III and ozonesonde measurements
- 2004
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In: Geophysical Research Letters. - 1944-8007 .- 0094-8276. ; 31:7, s. L07104-
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Journal article (peer-reviewed)abstract
- We present first statistical comparison results for stratospheric ozone density profiles retrieved from Odin/OSIRIS limb scattered radiance with 1220 coincident POAM III and 205 coincident ozonesonde measurements. Profiles are compared on a monthly basis from November 2001 to October 2002. Most of the time, differences between OSIRIS mean profiles and those measured by POAM III and ozonesondes were 5-7% between 15 km and 32 km, and within 15% above 32 km. In April-July 2002, OSIRIS mean profiles appear shifted downward by ∼1 km, introducing a difference of about 10% with POAM III and about 25% with ozonesonde profiles between 15 km and 32 km. This study demonstrates that outside the April-July 2002 period, the OSIRIS ozone profiles agree well with coincident ozonesonde and POAM III ozone profiles and make a valuable addition to the international ozone database available for research into global ozone change.
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| 6. |
- Schmeisser, D., et al.
(author)
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Oxide growth on SiC(0 0 0 1) surfaces
- 2001
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In: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 184:1-4, s. 340-345
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Journal article (peer-reviewed)abstract
- The oxidation of 6H SiC(0 0 0 1) surfaces is studied by high resolution photoelectron spectroscopy. We compare the oxides formed by HF dip, by room temperature treatment in ozone, and by thermal oxidation in air at 1000 °C, respectively. We find a stable intermediate layer in all investigated systems which differs from the bulk oxide that is stable up to 1200 °C. Our data suggest that the growth of the SiO2 layer proceeds via that intermediate silicate layer. © 2001 Published by Elsevier Science B.V.
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| 7. |
- Wingbrant, Helena, et al.
(author)
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MISiCFET chemical sensors for applications in exhaust gases and flue gases
- 2002
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In: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 433-4, s. 953-956
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Journal article (peer-reviewed)abstract
- A chemical gas sensor based on a silicon carbide field effect transistor with a catalytic gate metal has been under development for a number of years. The choice of silicon carbide as the semiconductor material allows the sensor to operate at high temperatures, for more than 6 months in flue gases at 300degreesC and for at least three days at 700degreesC. The chemical inertness of silicon carbide and a buried gate design makes it a suitable sensor technology for applications in corrosive environments such as exhaust gases and flue gases from boilers. The selectivity of the sensor devices is established through the choice of type and structure of the gate metal as well as the operation temperature. In this way NH3 sensors with low cross sensitivity to NOx have been demonstrated as potential sensors for control of selective catalytic reduction (SCR) of NOx by urea injection into diesel exhausts. Here we show that sensors with a porous platinum or iridium gate show different temperature ranges for NH3 detection. The hardness of the silicon carbide makes it for example more resistant to water splash at cold start of a petrol engine than existing technologies, and a sensor which can control the air to fuel ratio, before the exhaust gases are heated, has been demonstrated. Silicon carbide sensors are also tested in flue gases from boilers. Efficient regulation of the combustion in a boiler will decrease fuel consumption and reduce emissions.
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| 8. |
- Bohme, O, et al.
(author)
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Nanoparticles as the active element of high-temperature metal-insulator-silicon carbide gas sensors
- 2001
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In: Advanced Materials. - 0935-9648 .- 1521-4095. ; 13:8, s. 597-
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Journal article (peer-reviewed)abstract
- The sensor performance of MISiC (metal-insulator-silicon carbide) diode devices depends on their temperature pretreatment: an activation step at 600 degreesC leads to fast-responding devices with extraordinarily high signals but the devices fail when operated above 700 degreesC. The authors focus on the key role of nanoparticles in high-temperature gas sensor applications of these MISiC devices, presenting a model in which the interface dipole moment of nanoparticles is seen as the driving force and explaining the difference in response of capacitor-configuration and Schottky-diode-configuration devices.
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| 9. |
- Lloyd-Spets, Anita, et al.
(author)
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MISiCFET chemical gas sensors for high temperature and corrosive environment applications
- 2002
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In: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 389-3, s. 1415-1418
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Journal article (peer-reviewed)abstract
- A chemical gas sensor based on a silicon carbide field effect transistor with a catalytic gate metal has been under development for a number of years. The buried gate design allows the sensor to operate at high temperatures, routinely up to 600degreesC and for at least three days at 700degreesC. The chemical inertness of silicon carbide makes it a suitable sensor technology for applications in corrosive environments such as exhaust gases and flue gases from boilers. The selectivity of the sensor devices is established through the choice of type and structure of the gate metal as well as the operation temperature. In this way NH3 sensors with low cross sensitivity to NOx have been demonstrated as potential sensors for control of selective catalytic reduction (SCR) of NOx by urea injection into diesel exhausts. The hardness of the silicon carbide makes it for example more resistant to water splash at cold start of a petrol engine than existing technologies, and a sensor which can control the air to fuel ratio, before the exhaust gases are heated, has been demonstrated. Silicon carbide sensors are also tested in flue gases from boilers. Efficient regulation of the combustion in a boiler will decrease fuel consumption and reduce emissions.
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| 10. |
- Mikalo, RP, et al.
(author)
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Comparison of HF and ozone treated SiC surfaces
- 2000
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In: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 353-3, s. 219-222
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Journal article (peer-reviewed)abstract
- Single crystals of SiC were etched in hydrofluoric acid to remove the native oxide. Ozone exposure at room temperature is shown to give an oxide of about 0.7nm. The differences of interface and bulk oxides regarding their elemental composition and their oxidation states are reported as determined by photoelectron spectroscopy utilizing synchrotron radiation.
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