This figure is the top view of the Swift. The green line show the photon, and the two outward lines are the scattered photons from Swift. The irradiated area is 4 meter square coverall the satellite.
Swift Mass Model (SwiMM) is based on the Monte-Carlo simulation tool, Geant4. Geant4 transports the particle energy to calculate the every physical interaction.
SwiMM has the full geometry of Swift. There are three instruments, BAT, XRT, UVOT, and the space craft in detail. On SwiMM, we collectly describe their shapes, densities and 3 dimensional positions as much as possible basically on the design sheets. We call that the mass model.
We take account of the dominative physical interactions in our energy range,
for gamma.
We get the energy deposit and the positions (x,y,z) in the CZT detectors, we output this information to a FITS file.
In this Crab cal simulation, We create the same Crab spectrum (Photon Index = 2.10) and the generated photons are proper for the exposure of 1k sec.
On SwiMM, we irradiate the parallel rays of photon as follows, because the photons come from an infinite direction.
|
 |
Photon Index: 2.10 Energy Range: 5 keV < E < 1000 keV Generated Photons: 2.38x10^8 photons Machine Time: 12 hours on Intel PenM 1.70GHz
 |
Please see "Crab cal simulation on SwiMM" page.