Showing papers by "Oswald H. W. Siegmund published in 2001"
10 Dec 2001
TL;DR: The flight microchannel plate detectors to be used in the Cosmic Origins Spectrograph, a fourth generation instrument for the Hubble Space Telescope, have been calibrated in the laboratory before being integrated into the spectrograph as mentioned in this paper.
Abstract: The flight microchannel plate detectors to be used in the Cosmic Origins Spectrograph, a fourth generation instrument for the Hubble Space Telescope, have been calibrated in the laboratory before being integrated into the spectrograph. This paper presents the results of these calibrations that include measurements of the detector quantum efficiency, spatial resolution, spatial linearity, flat field, electronic livetime and the local count rate limit.
29 citations
10 Dec 2001
TL;DR: The Rosetta/ALICE instrument as discussed by the authors is a low-power (4 W) low-cost imaging spectrometer optimized for cometary ultraviolet spectroscopy, which is used to characterize the cometary nucleus, coma and nucleus/coma coupling of the Rosetta mission prime target comet 46P/Wirtanen.
Abstract: We describe the design, scientific objectives, and radiometric performance and calibration results of the Rosetta/ALICE instrument. ALICE is a lightweight (3.0 kg), low-power (4 W), low-cost imaging spectrometer optimized for cometary ultraviolet spectroscopy. Funded by NASA (with hardware contributions from CNES, France), ALICE will fly in 2003 on the ESA Rosetta Orbiter to characterize the cometary nucleus, coma, and nucleus/coma coupling of the Rosetta mission prime target comet 46P/Wirtanen. ALICE will also make observations of two asteroid flyby targets and of the Moon and Mars during the cruise portions of the Rosetta mission. It will obtain spatially-resolved, far-UV spectra of Wirtanen's nucleus and coma in the 700-2050A passband with a spectral resolution of 8-12A for extended sources that fill the entrance slit's 0.05 degree(s) x 6 degree(s) field-of-view. An improved derivative of the Rosetta/ALICE is also the UV spectrometer aboard the PERSI remote sensing suite proposed for the Pluto Kuiper Belt mission. ALICE uses modern technology to achieve its low mass and low power design specifications. It employs an off-axis telescope feeding a 0.15-m normal incidence Rowland circle spectrograph with a concave (toroidal) holographic reflection grating. The imaging microchannel plate (MCP) detector utilizes dual solar-blind opaque photocathodes of KBr and CsI deposited on a cylindrically-curved (7.5-cm radius) MCP Z-stack, and a matching 2-D cylindrically-curved double delay-line readout array with a 1024 x 32 pixel array format. Three data taking modes exist: (i) histogram image mode for 2-D images, (ii) pixel list mode with periodic time fiducials for temporal studies, and (iii) count rate mode for broadband photometric studies. Optical and radiometric sensitivity performance results based on integrated system level tests of the ALICE flight model are presented and discussed.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
19 citations
TL;DR: In this paper, a planar geometry for the transmission line was proposed to achieve sub-nanosecond pulse width with a high rise time of 380 ps with an active area of 1.8 cm.
Abstract: Fast particle detectors with subnanosecond pulse widths are key elements in modern time-of-flight mass spectrometers. Typically, an impedance matched transmission line from the extended anode to the coaxial cable is necessary to obtain fast pulses. We present an approach using a planar geometry for the transmission line. Thereby, the impedance match is realized with a transition from a 50 Ω suspended substrate microstrip line to a coaxial 50 Ω line. A prototype with an active area of 1.8 cm diameter including a strategy to reduce peak ringing was built and tested. The mean pulse width measured with a 1 GHz analog oscilloscope was 520 ps (full width at half maximum) with a rise time of 380 ps. The robust, compact, and low-weight design of the detector is well suited for an application in space, where weight, space, and power consumption are very limited resources.
16 citations
10 Dec 2001
TL;DR: In this paper, the cross strip anode is used for event position encoding with chip preamplifiers on the anode, subsequent analog to digital conversion of individual strip charge values and a software centroid determination.
Abstract: The cross strip anode is a coarse (o.5 mm) multi-layer metal and ceramic cross strip pattern. Event positions are encoded by direct sensing of the charge on each strip and subsequent determination of the charge cloud centroid for each event. This event position encoding is accomplished with chip preamplifiers on the anode, subsequent analog to digital conversion of individual strip charge values and a software centroid determination. The spatial resolution ( 1 MHz and with low power consumption (~2W) suitable for applications in space astrophysics.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
12 citations