SVOM MXT Lobster Eye Telescope Breadboard Model Testing Preliminary Results Dick Willingale Adrian Martindale, Jim Pearson, Charly Feldman, Julian Osborne University of Leicester

SVOM MXT Breadboard F=1000 mm Aperture 210x210 mm2 Total mass of integrated optic ~1 kg (~250 kg/m2)

Narrow Field Lobster Eye Optimization Maximize area at 1 keV For wide field L/d≈50 constant For narrow field - maximum area on axis L≈2.5dF/R F=1150 mm d=40 μm 21 square pore MCPs - each plate has aperture 38 x 38 mm2 L 1.22 – 2.74 mm L/d 31 - 68

Breadboard Model X-ray Testing Testing 1 plate Leicester TTF Source at 27 m F=1000 mm Al support frame – spherical surface R=2000 mm Machining accuracy ±10 μm 2x 20 μm plates, 2x 40 μm plates, 1x Ir coated plate

Measured Imaging 1.5 keV Single plate – off-axis 2 adjacent reflections - focus 0 reflection - straight through Single plate – off-axis Set at nominal focal length allowing for finite source distance Focused spot FWHM=6.0 arc mins 1 reflection - cross arm Note: MXT detector 19.3x19.3 mm

Measured Imaging 1.5 keV Single plate – off-axis in vertical direction 2 adjacent reflections - focus Edge of plate truncates cross arm Single plate – off-axis in vertical direction Set at nominal focal length allowing for finite source distance Length of cross-arm is the width of plate 38 mm, 2.18 degrees 1 reflection - cross arm

Results Single plate performance at nominal focus FWHM 6.0 arc mins (c.f. 8.5x7.5 arc mins for MIXS-T) Lobster eye performance better than Wolter I configuration but not as good as expected (4.5 arc mins) – possible explanation: The finite source distance of 27 m not corrected for Not at true focus Combination of slumping, shear and surface roughness worse than expected The measured efficiency ~70% of theoretical for the Ir coated plate From the MIXS-T results (which used Ir coating) we expect 85% theoretical The results are highly dependent on correct modeling of the test set up – the analysis is on-going The available data are not consistent – maybe because of spectral contamination in the X-ray beam or maybe incorrect modeling – more analysis required We hope to take more data early April 2015