X-ray Imaging Spectrometer
There are 4 X-ray Imaging Spectrometers
(XISs) on Suzaku.
Each XIS has its own X-ray Telescope that focuses X-rays onto it.
The detector is a 1024 by 1024 pixel X-ray sensitive
Charge Coupled
Device (CCD) fabricated by
MIT's Lincoln Laboratory. It is shown below.
Three XIS units use one type of CCD, and are sensitive to X-rays with
energis between 0.4 and 12 keV. The fourth XIS uses a different type
of CCD that covers 0.2-12 keV.
Millions of people use CCDs today, because they are used in digital
cameras and camcoders. In these devices, CCDs are used to count up
the number of visible light photons that landed in each pixel during
an exposure. CCDs are also good X-ray detectors. In this case,
they don't count the number of X-ray photons - they are used to measure
the energy of each X-ray photon instead. In other words, CCDs measure
X-ray spectra.
CCDs can distinguish an energy difference of 120 eV for a 6 keV X-ray photon
(that is, they have an energy resolution of 120 eV at 6 keV).
So the energy resolution of the XISs is not as good as that of the XRS,
but it's still good enough to be useful. It also gives the scientists
X-ray images - each XIS is a megapixel X-ray camera, the XRS is a 30 pixel
X-ray camera. Finally, XISs will be able to take data long after the
XRS has run out of liquid helium and solid neon.
XIS has been developed by a collaboration of Massachusetts Institute of
Technology, ISAS, University of Kyoto, and University of Osaka.
For more information, see
http://acis.mit.edu/acis/syseng/astroe/xis_home.html
You can now find out about the first data taken with the XIS in orbit!
Follow the links
to the news item
and to the the gallery
entry.
| 