Simulation of the Simbol-X telescope Maxime Chauvin - APC

Simulation of the Simbol-X telescope 

Maxime Chauvin 

CESR/Université de Toulouse-CNRS 

© CNES 2007 

M.Chauvin Simbol-X Symposium December 2 – 5 2008


Introduction 

Simulation tool for any grazing incidence telescope with deformations 

Application to Simbol-X: 

• understand and predict the behavior of the instrument 

• optimize the configuration of the instrument and assess the performance of the 

telescope: 

effective area 

angular resolution 

precision needed for the sensors 

tolerance on the drifts 

image reconstruction 

Outline of the presentation: 

I – Geometrical simulation 

II – Physical simulation 

III – Dynamical simulation 

IV – Performances 

© CNES 2007 




© CNES - GEKO 2007 

DSC 

20m 

Simbol-X telescope 

MSC 

1 – Focal plane 2 – Mirror module 




1 – Focal plane model 

Only one of the 2 detectors is simulated (HED) with these assumptions: 

• position of the detector at the focal length (20m) 

• matrix of 128 * 128 pixels with no gap 

• pixel size = 6.25 10 -4 m 

• perfect detection efficiency 

2 – Mirror module model 

• 100 concentric Wolter I shells 

(hyperbolic mirror + parabolic mirror) 

1) 

2) 

1 2 

20m 

0.7m 

0.6m 

• assembly and alignment errors (Harvey et al., optical engineering, 1996) 

• surface roughness 

• perfect mirror shapes 




3 – Ray tracing 

20m 

4 

3 

2 

1 

Detection 

Focalization 

Reflections 

Photon injection 

4 

3 

2 

1 




1 – Multilayer supermirrors reflection 

Model: 

• 250 bilayers of Pt / C 

• Depth graded multilayer (supermirror): 

(Joensen et al., applied optics, 1995) 

Reflection coefficient for E = 60 keV and = [ 0 – 20 ] arcmin: 

Monolayer mirror Multilayer mirror Multilayer supermirror 




2 – Sources 

• Point source 

• Source spectrum: 

single energy, ex: E = 30 keV 

linear range, ex: E = [ 0.5 – 80 ] keV 

power law, ex: 

• Multiple sources: 

1 telescope pointing in celestial coordinates 

1 list of sources in the FoV in celestial coordinates 

• Relative luminosity 




1 – In time Formation Flight 

© CNES 2007 

• Relative position degradation of the DSC express in TRF_M ( X, Y, Z ) 

• Relative attitude degradation of DSC & MSC express in their reference frame ( X, Y, Z ) 

Computed in the simulation by rotation matrix and reference frame changes 

Example of simulation: 

• 1 on axis source (200 000 photons) 

• 20 000 seconds 

• DSC movement from EADS Astrium enterprise 

lateral: [-0.5,0.5]cm, longitudinal: [-1.5,1.5]cm 

attitude: [-2,+2] arcmin 

• MSC movement 

attitude: [-20,+20] arcsec 

Useless data without image reconstruction… 




2 – Image reconstruction 

X 

Y 

Corrected position (blue) = Photon position (white) + corresponding X, Y of the detector 

Problem: only lateral drifts can be corrected 

Simulation of M22 FoV without corrections 

Simulation of M22 FoV with corrections 




3 – Sensors data 

Model: 

• Detector Spacecraft: 3 STR, 2 Lateral Sensors 

• Mirror Spacecraft: 3 STR, 3 targets for the Lateral Sensors 

Data simulated (angular positions) = real data + errors (bias + noise) 

Image reconstruction needs X, Y of the detector. 

computed by interferometry based on the Lateral Sensors data. 

X data of the DSC 

Y data of the DSC 




1 – Angular resolution with source off axis 

F = 20 m, 100 shells Pt/C bilayers with assembly, alignment and surface errors, 

no MSC & DSC movements 

On axis source 

Off axis source (6 arcmin) 

Half Energy Width (HEW): 

Diameter of the circle which 

contains 50% of the photons 

HEW 

Degradation of HEW with off axis: 

• 0.05 arcsec @ 3 arcmin 



HEW = 15 arcsec 

HEW = 15.2 arcsec 




2 – Effective area with source off axis 

F = 20 m, 100 shells of 250 depth graded Pt/C bilayers, no spider attenuation (~10%), 

no thermal filter attenuation 

On axis effective area (blue line): 

• 1280 cm @ 1 keV 

• 425 cm @ 30 keV 

• 170 cm @ 70 keV 

6 arcmin off axis effective area 

(pink line): 

• 840 cm @ 1 keV 

• 205 cm @ 30 keV 

• 50 cm @ 70 keV 




3 – Angular resolution with defocus 

F = 20 m, 100 shells of Pt/C multilayer (inner diameter = 286.26 mm, outer diameter = 697 mm), with 

assembly, alignment and surface errors 

On axis source with HEW = 15” @ 1 keV 

Blurring due to a defocus can 

not be corrected. 

Delta HEW with defocus: 

• 0.5 arcsec @ 20 mm 

• 1 arcsec @ 30 mm 

• 2 arcsec @ 40 mm 




4 – Image reconstruction with accuracy of sensors 

On axis source with HEW = 15” @ 1 keV 

DSC + MSC movements, image reconstruction with noisy sensors (values given @ 1 sigma) 

Lateral blurring is corrected 

relying on the sensors accuracy. 

Delta HEW with sensor errors: 

• 0.2 arcsec @ 1 arcsec 



…more analysis in M.Chauvin poster 



Conclusion 

We have developed a simulation tool able to: 

• Study the current configuration of Simbol-X 

• Optimize the optics of Simbol-X 

• Optimize the configuration for the scientific requirements 

• Test other telescope configurations 

Next steps… 

• macroscopic shell deformations 

• reflection geometry as a function of energy (X Ray Scattering) 

• model of the LED and HED with energy response of the detectors 



Thank you for your attention 

maxime.chauvin@cesr.fr 


















1 – Multilayer supermirrors reflection 

Model: 

• 250 bilayers of Pt / C 

• Depth graded multilayer: 

(Mao et al., applied optics, 1999) 

Computation: 

with 

(Joensen et al., applied optics, 1995) 

Parameters of the plot: 

E = 60 keV 

= [ 0 – 20 ] arcmin 

Range of Simbol-X: 

E = [ 0.5 – 80 ] keV 

= [ 0 – 27 ] arcmin

Simulation of the Simbol-X telescope Maxime Chauvin - APC

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