Measurements with MONCH, a 25 μm pixel pitch hybrid pixel detector

MONCH is a hybrid silicon pixel detector based on charge integration and with analog readout, featuring a pixel size of 25 x 25 mu m(2). The latest working prototype consists of an array of 400 x 400 identical pixels for a total active area of 1 x 1 cm(2). Its design is optimized for the single photon regime. An exhaustive characterization of this large area prototype has been carried out in the past months, and it confirms an ENC in the order of 35 electrons RMS and a dynamic range of similar to 4 x 12 keV photons in high gain mode, which increases to similar to 100 x 12 keV photons with the lowest gain setting. The low noise levels of MONCH make it a suitable candidate for X-ray detection at energies around 1 keV and below. Imaging applications in particular can benefit significantly from the use of MONCH: due to its extremely small pixel pitch, the detector intrinsically offers excellent position resolution. Moreover, in low flux conditions, charge sharing between neighboring pixels allows the use of position interpolation algorithms which grant a resolution at the micrometer-level. Its energy reconstruction and imaging capabilities have been tested for the first time at a low energy beamline at PSI, with photon energies between 1.75 keV and 3.5 keV, and results will be shown.