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Background modelling for LEO satellites with high orbital inclination is not an easy task. The diffuse background component is dominated by the background coming from strong interactions with Earth magnetosphere trapped particles. Magnetic shielding is variable along the orbits and crosses through the SAA induce high radioactivity decay counting ratios. The aim of this paper is to present a model for the background total counting ratio of the 17 operative CdZnTe detectors on LEGRI in the short time scales and for observing periods outside crosses through SAA having enough time to cool LEGRI after the last SAA transit. Fluxes measured have been modelled in terms of the McIlwain parameter L using polynomial fits and exponential laws in terms of the geomagnetic cut-off rigidity used on COMPTEL background modelling. A discussion of the results is also included. 相似文献
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Julia Suso Pere Blay Almudena Robert Victor Reglero Chris J. Eyles 《Astrophysics and Space Science》2001,276(1):299-309
LEGRI has been operating successfully on MINISAT-01 since its switch-on the 22nd of May 1997. HouseKeeping (HK) data have been continuously receivedfor nearly two years by LEGRI SOC in Valencia, and subsequently checked on adaily basis and then stored for long term monitoring analysis.LEGRI HouseKeeping data include three critical operating parameters:temperature, power and polarisation voltages. Six temperature sensors arespread over the different LEGRI units: Detector Unit, Data Processing Unit,High Voltage Unit and Star Sensor. Voltages are measured at eight differentpoints. Detector Unit temperature and polarisation voltage are thecritical parameters for LEGRI operation. Solid state detectors aresensitive to changes not only in polarisation but also in temperature.Around one and a half million of measurements for each of the HK fourteen parameters have been recorded and analysed. The data show a very remarkablestability, within the expected margins, and the averages are very close to theoptimal design values. Special attention has been paid to the detectorpolarisation voltages analysis with a mean value of 286 ± 2 V when the detectors are operating. Thermal control over all the LEGRI units shows a remarkable stability in their temperatures.On the detector plane a mean value of T
det = 13 ± 2 °C has been found.We can therefore conclude that LEGRI as a system has been operating withinits optimal design conditions. We also want to point out the excellentperformance of the MINISAT-01 thermal control system. 相似文献
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VICTOR VAN STRAELEN 《地质学报》1928,7(2):200-212
1.—Introduction. Father E. Licent, S. J., during one, of his travels in Eastern Mongolia, discovered, in the Lycoptera and Ephemeropsis shales, the remnants of three Decapod Crustaceans. They belong to a new species, which shall be designated as Astacus licenti, nov. sp., in honour of that indefatigable explorer, that is Father Licent. 相似文献
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Ultra-trace (<1 ppm) amounts of thorium in NIM-D and NIM-P geochemical reference materials are determined by the technique of cation exchange chromatography - spark source mass spectrography. After dissolution, thorium is selectively separated from all other elements on a column of AG50W-X4 resin. The thorium eluate is concentrated and evaporated onto silver powder together with 1 000 ng of uranium which serves as the internal standard. Mass spectrographic analysis of this spiked silver powder is carried out with a spark source mass spectrograph. 相似文献
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A new thermobarometer, based on the equilibrium:
has been calibrated with experiments carried out in the piston-cylinderapparatus. Reversed equilibria were obtained using well-calibrated2.54 cm NaCl furnace assemblies and Ag80Pd20capsules with fO2bufferedat or near iron-wustite. The equilibrium is located between5.25.4, 6.66.8, and 8.68.8 kb at 880, 940,and 1020?C, respectively, and at 5.2 and 8.8 kb between 865880and 10201030?C, respectively. X-ray refinement data indicate that the hercynite (a = 8.15546?) has approximately 18 per cent inverse character. M?ssbauerspectra reveal that 4 mol per cent of the Fe is ferric (2 percent magnetite component). Broad Mossbauer lines and a Fe2+energy level splitting of 3.7 kJ mol1 calculated fromthe Mossbauer spectra are consistent with the X-ray determineddegree of inversion, although no separate octahedral Fe2+ spectraldoublet is resolved. Calibration of this equation allows calculation of the equilibrium:
Thermobarometers based on the above equilibria are widely applicablein granulite fades rocks and yield pressure/temperature datathat are consistent with other well-calibrated barometers andthermometers. 相似文献
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Results are presented for the determination of trace quantities of cobalt in three South African primary rock standards and in four secondary rock standards. Cohalt is separated from all other elements using a selective ion exchange separation procedure and determined by electrothermal atomic absorption spectrophotometry. 相似文献