93 research outputs found
The SMILE Soft X-ray Imager (SXI) CCD design and development
SMILE, the Solar wind Magnetosphere Ionosphere Link Explorer, is a joint science mission between the European Space Agency and the Chinese Academy of Sciences. The spacecraft will be uniquely equipped to study the interaction between the Earthâs magnetosphere-ionosphere system and the solar wind on a global scale. SMILEâs instruments will explore this science through imaging of the solar wind charge exchange soft X-ray emission from the dayside magnetosheath, simultaneous imaging of the UV northern aurora and in-situ monitoring of the solar wind and magnetosheath plasma and magnetic field conditions.
The Soft X-ray Imager (SXI) is the instrument being designed to observe X-ray photons emitted by the solar wind charge exchange process at photon energies between 200 eV and 2000 eV. X-rays will be collected using a focal plane array of two custom-designed CCDs, each consisting of 18 ”m square pixels in a 4510 by 4510 array.
SMILE will be placed in a highly elliptical polar orbit, passing in and out of the Earthâs radiation belts every 48 hours. Radiation damage accumulated in the CCDs during the missionâs nominal 3-year lifetime will degrade their performance (such as through decreases in charge transfer efficiency), negatively impacting the instrumentâs ability to detect low energy X-rays incident on the regions of the CCD image area furthest from the detector outputs. The design of the SMILE-SXI CCDs is presented here, including features and operating methods for mitigating the effects of radiation damage and expected end of life CCD performance. Measurements with a PLATO device that has not been designed for soft X-ray signal levels indicate a temperature-dependent transfer efficiency performance varying between 5 Ă 10â5 and 9 Ă 10â4 at expected End of Life for 5.9 keV photons, giving an initial set of measurements from which to extrapolate the performance of the SXI CCDs
Kac-Moody algebras in perturbative string theory
The conjecture that M-theory has the rank eleven Kac-Moody symmetry e11
implies that Type IIA and Type IIB string theories in ten dimensions possess
certain infinite dimensional perturbative symmetry algebras that we determine.
This prediction is compared with the symmetry algebras that can be constructed
in perturbative string theory, using the closed string analogues of the DDF
operators. Within the limitations of this construction close agreement is
found. We also perform the analogous analysis for the case of the closed
bosonic string.Comment: 31 pages, harvmac (b), 4 eps-figure
Lectures on conformal field theory and Kac-Moody algebras
This is an introduction to the basic ideas and to a few further selected
topics in conformal quantum field theory and in the theory of Kac-Moody
algebras.Comment: 59 pages, LaTeX2e, extended version of lectures given at the Graduate
Course on Conformal Field Theory and Integrable Models (Budapest, August
1996), to appear in Springer Lecture Notes in Physic
A rotação de cultura reduz a matocompetição e aumenta o teor de clorofila e a produtividade do arroz
Bio-analytical Assay Methods used in Therapeutic Drug Monitoring of Antiretroviral Drugs-A Review
Thermodynamics of polymolecular duplexes between phosphate-methylated DNA and natural DNA
(Bio)chemische eigenschappen van parallelle DNA-duplices gestabiliseerd door polylysine : structuur, stabiliteit, enzymatische herkenbaarheid
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