Response Matrices

Page Under Development. Area and vignetting data under revision as of March 23, 2015.  For simulation activities at the moment please use these links to the X-IFU and WFI consortia pages (replicated below as appropriate).

Following the CDF activity, the industry Phase A study will investigate system designs that include two reference telescope designs. In order to support trade-off studies, the science performance must be assessed for the different cases. To carry out simulations it is necessary to use response functions representing the possible instrument and telescope designs. In the near term this work must be continued for

1)      Informing the AWG about the potential science losses with reduced area telescope

2)      Refining the science requirements through simulating various observation scenarios

3)      Developing associated Calibration requirements that may impact on test facility designs

4)       Updating the Mock Observation Plan

Instrument response matrices will be provided by the instrument teams, with links provided below.

Mirror designs for the Athena proposal were coordinated by Dick Willingale, whilst for CDF study, ESA internal estimates were produced by Tim Oosterbroek in close collaboration with the optics technology development experts. Some significant effort has been expended in harmonising the geometric components of these different models

Two major geometrical options need to be considered for reference designs:

Mirror outer diameter

–        the CDF version was limited by cost and launch adapter constraints for a value  0.25m<R< 1.19m  (comprising 15 annuli of standard SPO modules)

–        the industry maximum design point will be for 0.25m<R<1.47 m (comprising 19 annuli of SPO module )

SPO Rib Spacing

–        Successive Si plates are bonded by thin (~0.17mm) ribs which in the developments to date have been at a pitch of 1mm

–        New developments for minimising the inner diameter, aim to increase the rib pitch. Until these developments are demonstrated, the eventual rib parameters and even how they would change with radius in the mirror are uncertain. We assume a pitch ~2.47mm

Clearly the mirror outer diameter will have a strong impact on the effective collecting area (mainly at soft X-ray energies). Increasing the rib pitch will improve the aperture utility factor, but as an important secondary effect also reduce the off-axis vignetting losses. Response matrices of these 2x2 set of mirror options could be considered, even for the case of comparing on-axis responses. Furthermore, estimating the effect on key metrics like Survey Speed have to account for the average field response (i.e. effective area weighted with the vignetting at different field of view radii). For the current exercises we provide response sets for the two mirror diameter cases, and fix the pore specing at the optimistic case.

Component Data Files

Mirror Effective Area On Axis

On-axis mirror effective area files courtesy R Willingale

CDF Configuration 1.18 m radius but 2.3 mm pores ASCII

Proposal Configuration 1.47m radius but 2.3 mm pores ASCII


Files describing the vignetting function s a function of energy and radius within the field of view (courtesy T.Oosterbroek)

CDF Configuration 1.18 m radius but 2.3 mm pores FITS

Proposal Configuration 1.47m radius but 2.3 mm pores FITS


Instrument files


X-IFU Efficiency: N/A WFI Efficiency: ASCII
X-IFU Redistribution: FITS WFI Redistribution: FITS
X-IFU Effective area: Web portal WFI Effective area: FITS



X-IFU background spectra: Web portal WFI background spectra: FITS (and documentation)


Chandra and XMM-Newton soft proton flares are a strong function of radius from Earth, therefore at L2 expected to be very much lower, except for episodes of plasma sheet crossing

Diffuse X-ray Background Model: (quiescent Solar Wind Charge Exchange)




0.099 keV




APEC  Norm 1.7 10-6 (10-14/(4Π(DA(1+Z))2)) ∫ NENH D


NH 0.018

1022 cm-2

APEC kT 0.225 keV
APEC Abundance 1  
APEC Redshift 0  
APEC Norm 7.3 10-7  
PL Index 1.45  
PL Norm 2 10-7  Ph /KeV/cm2/s @1keV





Responses assume that 2xHEW includes all point source counts.   Extended source case assumes normalisation to 1 sq arcmin - PLEASE ADJUST ACCORDING TO YOUR SIMULATION CASE (e.g. change the BACKSCAL keywords)
Exercise care in interpreting the simulations results: assumptions on coating efficiency, coating thickness vs. annulus, roughness, etc. make energy-dependent effects at the ~10% level.