Exploring the limits of hybrid pixel detectors with MÖNCH R.Dinapoli*,1,A.Bergamaschi1,M.Brückner1,S.Cartier1,2,D.Greiffenberg1,J.Jungmann-Smith1,D.Mezza1,A.Mozzanica1,M.Ramilli1,B.Schmitt1,X.Shi1,G.Tinti1 1-Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland 2-Institut for Biomedical Engineering, University and ETH Zürich, Zürich, Switzerland * Corresponding author; roberto.dinapoli@psi.ch High resolution using charge sharing MOTIVATION: Understand the limits of hybrid pixel detectors (pitch,energy & position resolution…) for possible applications in: The working principle Hi-res X-ray imaging, spectrometers, X-ray tomography, low energy X-ray detection, resonant and nonresonant inelastic X-ray scattering Radiation conversion Charge collection after drift and diffusion Low resolution analog image High resolution digital image If the photon flux is low enough with respect to the frame rate, impinging photons can be “singled out”. In this case the analog information delivered by all pixels sharing the charge generated by the impinging photon can be interpolated to get a resolution that is much better than the pixel pitch. WHY CHARGE INTEGRATION? Higher incoming photon flux (both XFELS and synchrotrons) Charge sharing can improve resolution (“low flux” ) Energy information (“low flux” ) and lower energies (~keV) accessible Challenges: sensitive to leakage current, bump-bonding at fine pitch, complex calibration, huge data throughput/amount Interpolation at work with Gotthard Charge integrating hybrid pixel detector with 25 x 25 μm² pixel size Gotthard is a strip detector (20 μm pitch) The sample (kidney stone) is scanned in front of the strips A 2 μm slit defines the vertical opening 12 keV beam 20 μm pitch 0.5 μm bins MÖNCH 0.3 prototype MÖNCH0.3 readout chip (1x1cm2) bump bonded to 4 small sensors (4x4mm2) NO INTERPOLATION WITH INTERPOLATION * MÖNCH with a nanoscope Magnification: ~80x Siemens star images Sample under test: gold bookmark *CDS: correlated double sampling Y pixel # Counts Mönch (25μm pixel, with 5x image stitching and charge interpolation, not cooled) Targeting Hi-res low flux applications 400x400 pixels of 25x25μm² Selectable preamp gain (lowG, highG) Selectable CDS* gain (1-2-4) High testability (e.g. CDS* can be bypassed) Preliminary results very similar to MÖNCH0.2 ~3 μm (x80) X pixel # Direct X-ray tube beam Single photon image Photonic Science CCD (4μm pixel, with 2x image stitching, cooled) Performance summary ~3 μm (x80) Pixel pitch [μm] 25 World smallest pitch for hybrid pixel detectors! Bump-bonding yield (on 4x4mm2) 99.99% Stampanoni et al.,Physical Rev. B 81,140105(R)(2010) CHIP SETTINGS NOISE (e-rms) World lowest noise for hybrid pixel detectors! MÖNCH spectral performance Preamp HighGain,CDS Gain=4 Preamp LowGain,CDS Gain=4 Preamp LowGain,CDS Gain=1 31 50 214 Hybrid pixel detectors become competitive with monolitic active pixel detectors and CCDs Monochromatic beam at 20 keV The fluorescence lines come from the detector itself No spectral information from single pixel with no cuts Clusterization increases the noise Monochromatic beam at 20 keV The fluorescence lines come from the detector itself No spectral information from single pixel with no cuts Clusterization increases the noise Main beam 20 keV Si escape 18.2 keV In 3.3 keV Ti (4.5 keV) Cu (8.0 keV) Au 9.7 keV Rb? (13.3 keV) Ni 7.4 keV Br (11.9 keV) Spectral resol. @16 keV [ev,FWHM] <450 Spatial resolution with interp. [μm] ~2 Compton Edge 1.45 keV Single chip with 800x1200 pixels (1Mpixel) Module with 4x3 cm2 and 2Mpixel 8 kHz frame rate Low energy (~400eV ) detection development High dynamic range version (implementing dynamic gain switching) Future work