Optics and Simulations Jenny Carter, Steve Sembay & Andy Read

1. Optics and Simulations Jenny Carter, Steve Sembay & Andy Read

2. Telescope set-up Slumped micro channel plate with detector (CCD) at focal plane Curved focal plane

3. Introduction to the MCP or MPO • Microchannel plates or micropore optics • Matrix of channels – can act as a detector or optic • Channel length: ~ 1mm • Manufactured using core-cladding process; channel glass and core glass drawn down in stacks, core glass etched away to leave channel matrix. • Advantages: light-weight, compact, high effective area • Disadvantages: may be flimsy when made very large • Channel aspect ratio: length-diameter L/D • Different packing and pore shapes available • Typical L/Ds: small – 20:1, large – 500:1 • Different style slumping possible

4. Microchannel plate optics

5. Aspects to consider • Optics – some features • Focal length • Point spread function (PSF) • Choice of materials, coatings • Channel aspect ratio OPTIMISATION OF OPTICS SYSTEM • Detector system – Steve’s talk OPTIMISATION OF DETECTOR SYSTEM • Combined simulations - eventually OPTIMISATION OF TELESCOPE

6. PSF • Pyramid structure due to reflections on different walls in the channels • Number of reflections function of incident angle and aspect ratio • Characteristic cruciform shape

7. Effective area • Dependent on energy, the coating and radius of curvature of the optic • Combined with quantum efficiency and filter transmission etc. of the final system, an auxiliary response file can be created

8. Simulations at Leicester so far • Based on Robertson and Cravens models • Basic plan: • use model to determine SWCX flux • model spectra to find count rate • use count rates to simulate images for different FOVs, solar wind conditions etc.

9. Simulation set-up • Looked at different FOVs • Used effective area curve for another Leicester slumped-MCP project – peak at ~ 13 cm2 • Use Xspec fitting to fake spectra, 0.2 – 2 keV • Use adapted XMM-Newton MOS camera response, low-energy resolution improvement: ~ 50 eV FWHM @ 600 eV

10. Model basis • Snowden et al., HDFN and SWCX, ApJ, 610, 1182, 2004, scale to model

11. Bkg components • Background (bkg) components: • sky bkg • particle-induced bkg • lunar bkg • Sky bkg model using Snowden et al. components • Sky bkg scaled to values in the literature (Lumb et al., A.&A. 389, 2002) • Particle-bkg scaled to XMM-Newton MOS • Limitations: particle-induced bkg scaling, no temporary/spatial variation of sky bkg, no instrumental lines Sky: MW-halo, local halo, cosmic bkg, local hot bubble wabs * (raymond + powerlaw + raymond) + vapec + raymond

12. MagEX Simulations • ‘Storm’ Conditions • Typical diffuse sky and detector background • MCP Optic • 0.2-2.0 keV • FOV 9x9 deg • Lunar background can range from negligible to comparable with the magnetosheath • Lunar bkg values taken from Figure 6., original LSSO proposal (azimuthal angle of 0 deg., zenith angle of 90 deg.)

13. MagEX Simulations • ‘Normal’ Conditions • Typical diffuse sky and detector background • MCP Optic • 0.2-2.0 keV • FOV 20x20 deg • Pixel size 10 arcmin • Longest exposures represent stacking of data at similar sun-moon-earth angles and similar solar conditions 1 ks 10 ks 100 ks 1 Ms

14. MagEX Simulations • ‘Storm’ Conditions • Typical diffuse sky and detector background • MCP Optic • 0.2-2.0 keV • FOV 20x20 deg • Pixel size 10 arcmin • Longest exposures represent stacking of data at similar sun-moon-earth angles and similar solar conditions 1 ks 10 ks 100 ks 1 Ms

15. MagEX Simulations • ‘Storm’ Conditions • Typical diffuse sky and detector background • MCP Optic • 0.5-0.6 keV(Oxygen) • FOV 20x20 deg • Pixel size 10 arcmin • Longest exposures represent stacking of data at similar sun-moon-earth angles and similar solar conditions 1 ks 10 ks 100 ks 1 Ms

16. Simulation software for optics-detector system Source rays Optic Detector • Sequential ray tracing software • Developed at Leicester • Uses q, like IDL • What we can vary: • source setup – finite/infinite distance or diffuse (uniform random distribution over a hemisphere), number of rays • optics setup – radius of curvature, channel aspect ratio, surface roughness, component materials • detector setup – detector type (whether planar, spherical etc.), radius of curvature • other aspects – surface qualities, supporting structures etc. • Want to optimise PSF and effective area for a diffuse source

17. Simulation software for experiment in lunar orbit • Satellite tool kit (STK), widely used • Images • viewpoints, pointings, FOVs, elevations of instruments ….. • movies • Output • wide range of possible output parameters. For example orbital info so can add to model of magnetosheath emission • take info over time to model run in conjunction with temperature simulations, illumination over time etc.

18. Plans • Run sequential ray tracing for various telescope and detector configurations • Concentrate on various aspect ratios for diffuse emission • Use Sat Tool Kit software to simulate FOV from the Moon over different mission lifetimes, observing times and lunar locations and phase of lunar night • Address various issues from the current simulations: particle background contributions, lunar contributions, more detailed effective area consideration, proper vignetting consideration • Study possibilities of curved or side-buttable CCDs to be placed at the detector plane

19. STK examples • Equatorial, 20x20 and 30x30 degrees • Polar (north), 20x20 and 30x30 degrees • Polar (south), 20x20 and 30x30 degrees – with ROSAT bright source catalogue > 10 ct/s added to sims • Blue grid – Earth inertial frame • Yellow vector – Sun pointing • Purple sphere – Earth centred, 10 Earth radii • Green rectangle - FOV