J. Gethyn Timothy

Curved‐channel microchannel array plates

Microchannel array plates (MCPs) in which the channels are curved to inhibit ion‐feedback, in an identical manner to that employed in a conventional channel electron multiplier, have been fabricated and their performance characteristics have been evaluated. These devices represent a major advance in MCP technology since a single curved‐channel MCP can be operated stably at high gain in the pulse‐counting mode. Gains of greater than 106 electrons pulse−1 have been obtained at applied potentials of the order of 2000 V with maximum count‐rate capabilities exceeding 105 counts mm−2s−1 and lifetimes exceeding 2.5×1011 counts mm−2.

Multi-Anode Microchannel Arrays

The Multi-Anode Microchannel Arrays (MAMAs) are a family of photoelectric photon-counting array detectors being developed for use in instruments on both ground-based and space-borne telescopes. These detectors combine high sensitivity and photometric stability with a high-resolution imaging capability. Visible-light (10 × 10)-pixel, (1 × 512)-pixel and (1 × 1024)-pixel detector systems are now being used at ground-based telescopes and an ultraviolet (1 × 1024)-pixel detector has been flown in a sounding-rocket spectrometer. A (16 × 1024)-pixel system is currently under test in the laboratory and (24 × 1024)-pixel and (256 × 1024)-pixel systems will be available later this year. The construction and modes-of-operation of the different detector systems are described and the latest performance data are presented.

Detector arrays for photometric measurements at soft X-ray, ultraviolet and visible wavelengths

The capabilities of conventional optical systems and detectors have proved inadequate for many measurements in space astronomy. In order to overcome these limitations a family of photoelectric photon-counting array detectors has been developed for use in instruments on space-borne telescopes. The Multi-Anode Microchannel Array (MAMA) detector system can be operated in a windowless configuration at extreme-ultraviolet and soft x-ray wavelengths or in a sealed configuration at ultraviolet and visible wave-lengths. MAMA detectors with up to (512 x 512)-pixels are now under evaluation. In this paper the construction and modes-of-operation of the MAMA detectors are described and the designs of spectrometers utilizing the array detectors are outlined.

Multianode microchannel array detectors for Space Shuttle imaging applications

The Multi-Anode Microchannel Arrays (MAMAs) are a family of photoelectric, photon-counting array detectors that have been developed and qualified specifically for use in space. MAMA detectors with formats as large as 256 x 1024 pixels are now in use or under construction for a variety of imaging and tracking applications. These photo-emissive detectors can be operated in a windowless configuration at extreme ultraviolet and soft x-ray wavelengths or in a sealed configuration at ultraviolet and visible wavelengths. The construction and modes-of-operation of the MAMA detectors are briefly described and the scientific objectives of a number of sounding rocket and Space Shuttle instruments utilizing these detectors are outlined. Performance characteristics of the MAMA detectors that are of fundamental importances for operation in the Space Shuttle environment are described and compared with those of the photo-conductive array detectors such as the CCDs and CIDs.

The Status Of The Multi-Anode Microchannel Arrays (MAMA) Detector, Development Program

The Multi-anode Microchannel Arrays (MAMAs) are a fa,Hily of photoelectric photon-counting array detectors being developed for use in instruments on both ground-based and spaceborne telescopes. MAMA. detectors can be operated in a windowless configuration at extreme-ultraviolet and soft x-ray wavelengths or in a sealed configuration at ultraviolet and visible wavelengths. Prototype MAMA detectors with up to 512 x 512 pixels are now being tested in the laboratory and telescope operation of a simple (10 x 10)-pixel visible-light detector has been initiated. In this paper the methods of construction and the modes of operation of the MAMA detectors are described and the status of the development program is reviewed.

Space Telescope Imaging Spectrograph detectors and ultraviolet signal-to-noise capabilities

The space telescope imaging spectrograph (STIS) was designed as a versatile spectrograph capable of maintaining or exceeding the spectroscopic capabilities of both the Goddard High Resolution Spectrograph and the Faint Object Spectrograph (FOS) over the broad bandpass extending from the UV through the visible. STIS achieves performance gains over the aforementioned first generation Hubble Space Telescope instruments primarily through the use of large a real detectors in both the UV and visible regions of the spectrum. Simultaneous spatial and spectral coverage is provided through long slit or slitless spectroscopy. This paper will review the detector design and in-flight performance. Attention will be focussed on the key issue of S/N performance. Spectra obtained during the first few months of operation, illustrate that high signal-to-noise spectra can be obtained while exploiting STISs multiplexing advantage. From analysis of a single spectrum of GD153, with counting statistics of approximately 165, a S/N of approximately 130 is achieved per spectral resolution element in the FUV. In the NUV a single spectrum of GRW + 70D5824, with counting statistics of approximately 200, yields a S/N of approximately 150 per spectral resolution element. An even higher S/N capability is illustrated through the use of the fixed pattern split slits in the medium resolution echelle modes where observations of BD28D42 yield a signal-to-noise of approximately 250 and approximately 350 per spectral resolution element in the FUV and NUV respectively.

First results from the Space Telescope Imaging Spectrograph

The STIS instrument was installed into HST in February 1997 during the Servicing Mission 2. It has almost completed checkout and is beginning its science program, and is working well. Several scientific demonstration observations were taken to illustrate some of the range of scientific uses and modes of observation of STIS.

Photoelectric array detectors for use at XUV wavelengths

The characteristics of photoelectric detector systems for use at visible-light, ultraviolet, and X-ray wavelengths are briefly reviewed in the context of the needs of the Spacelab solar-physics facilities. Photoelectric array detectors for use at XUV wavelengths between 90 and 1500 Å are described, and their use in the ESA Grazing-Incidence Solar Telescope (GRIST) facility is discussed.