. ACIS Schematic
ACIS schematic layout overhead view to illustrate the location of the imaging (ACIS-I) and spectroscopic (ACIS-S) arrays of CCD ships. Chips S1 and S3 are back-illuminated chips; all of the other chips are front-illuminated.
ACIS schematic layout overhead view to illustrate the location of the imaging (ACIS-I) and spectroscopic (ACIS-S) arrays of CCD ships. Chips S1 and S3 are back-illuminated chips; all of the other chips are front-illuminated.
. High-Resolution Camera (HRC)
The HRC accurately records the position, number, and energy of X-rays. The camera consists of two clusters of 69 x 06 lead oxide (PbO2) glass tubes, 1.2 mm long and 10m in diameter (1/8th the diameter of a human hair.) The X-rays strike the tubes and release electrons that are accelerated down the tubes at high voltage. The electrons trigger the release of other electrons, and at the end of the tubes millions of electrons strike a grid and produce a finely detailed map of the source which emitted the X-rays.
The HRC accurately records the position, number, and energy of X-rays. The camera consists of two clusters of 69 x 06 lead oxide (PbO2) glass tubes, 1.2 mm long and 10m in diameter (1/8th the diameter of a human hair.) The X-rays strike the tubes and release electrons that are accelerated down the tubes at high voltage. The electrons trigger the release of other electrons, and at the end of the tubes millions of electrons strike a grid and produce a finely detailed map of the source which emitted the X-rays.
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. Chandra Spacecraft
Schematic of the Chandra spacecraft with an exploded view of the science instruments.
Schematic of the Chandra spacecraft with an exploded view of the science instruments.
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. CCD Imaging Spectrometer (ACIS) Illustration
A diagram of Chandra CCD Imaging Spectrometer (ACIS), which is used for studying the temperature variation across X-ray sources such as vast clouds of hot gas in intergalactic space.
A diagram of Chandra CCD Imaging Spectrometer (ACIS), which is used for studying the temperature variation across X-ray sources such as vast clouds of hot gas in intergalactic space.
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. High Energy Transmission Gratings
There are two instruments aboard Chandra dedicated to high resolution spectroscopy: the High Energy Transmission Grating Spectrometer (HETGS) and the Low Energy Transmission Grating Spectrometer (LETGS). Each spectrometer is activated by swinging an assembly into position behind the mirrors. The assembly holds hundreds of gold transmission gratings: when in place behind the mirrors, the gratings intercept the X-rays reflected from the mirrors.
There are two instruments aboard Chandra dedicated to high resolution spectroscopy: the High Energy Transmission Grating Spectrometer (HETGS) and the Low Energy Transmission Grating Spectrometer (LETGS). Each spectrometer is activated by swinging an assembly into position behind the mirrors. The assembly holds hundreds of gold transmission gratings: when in place behind the mirrors, the gratings intercept the X-rays reflected from the mirrors.
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. Grating Cross Section
Two types of gratings are in the HETG, in order to distinguish between them, the HEG and MEG gratings are oriented at slightly different angles, so that the X-rays are diffracted in an "X" pattern on the detector. The HETG grating facets are made of bars which are spaced closer together than a wavelength of visible light; it would take hundreds of bars to equal the thickness of a sheet of paper. The bars are supported by plastic membranes which are as thin as a soap bubble, yet can withstand the trauma of a shuttle launch. The gratings take advantage of the fact that the gold bars are partially transparent to X-rays, so that the diffraction is more efficient, and more X-rays are captured in the high resolution spectrum.
Two types of gratings are in the HETG, in order to distinguish between them, the HEG and MEG gratings are oriented at slightly different angles, so that the X-rays are diffracted in an "X" pattern on the detector. The HETG grating facets are made of bars which are spaced closer together than a wavelength of visible light; it would take hundreds of bars to equal the thickness of a sheet of paper. The bars are supported by plastic membranes which are as thin as a soap bubble, yet can withstand the trauma of a shuttle launch. The gratings take advantage of the fact that the gold bars are partially transparent to X-rays, so that the diffraction is more efficient, and more X-rays are captured in the high resolution spectrum.
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