Speaker
Hauf Steffen
(TU Darmstadt, Darmstadt)
Description
The International X-ray Observatory (IXO) is a planned high sensity
next-generation X-ray telescope, jointly built by ESA, NASA and JAXA,
which is projected to be launched in the 2020 timeframe. The main
scientific goals of IXO include the study of AGN, the
diffuse x-ray background as well as accretion discs around black holes and
neutron stars which will aid the understanding of cosmic evolution and the physics of matter under extreme conditions. In order to achieve these goals IXO will need to surpass
currently flighing or operating x-ray missions by at least an order of magnitude in
terms of sensitivity while simultaneously extending the energy range for
imaging observations up to 40 keV.
One of the main instruments aboard IXO will be the Wide Field Imager
(WFI), which will employ DePFET technology for high resolution spectral
imaging (1 arcsec, energy resolution of < 150 eV (FWHM) at 6 keV) in the 0.1-15
keV energy range, while at the same time achieving the low background rate
of approx. 10E-4 cts/cm²/s/keV required for high sensitivity observations
of faint sources.
A prerequiste for these low background rates is an optimized shielding
concept which makes use of a graded-Z shield. As is common for many new
satellite projects the Geant4 Monte Carlo tool kit was used for simulating
the expected particle and background flux and optimizing shielding and
other background reduction measures.
We present our current estimates of the IXO WFI cosmic proton induced
background as well as an analysis of its constituents. We also present our
current shielding design and background reducing postprocessing
algorithms. Finally we point out problems within the simulation which have
come to our attention while modelling a realistic WFI entrance window,
which requires an accurate treatment of particle and photon interactions
in material layers with a thickness of a few nanometers.
Primary author
Hauf Steffen
(TU Darmstadt, Darmstadt)
Co-authors
Alexander Stefanescu
(MPI Halbleiterlabor, Munich, Johannes Gutenberg Universty, Mainz)
Chris Tenzer
(IAA Tuebingen, Tuebingen)
Dieter H.H. Hoffmann
(TU Darmstadt, Darmstadt)
Eckard Kendziorra
(IAA Tuebingen, Tuebingen)
Georg Weidenspointner
(MPI Halbleiterlabor, Munich)
Lothar Strueder
(MPI Halbleiterlabor, Munich)
Maria Grazia Pia
(INFN Genova, Genova)
Markus Kuster
(XFEL, Hamburg)
Philipp-M. Lang
(TU Darmstadt, Darmstadt)