The adaptive gain integrating pixel detector (AGIPD): A detector for the European XFEL. development and status

The European XFEL [1] under construction in Hamburg will provide fully coherent, 100 fs long X-ray pulses, with 1012 photons at 12 keV. The high intensity per pulse will allow recording diffraction patterns of single particles or small crystals in a single shot. As a consequence the 2D detectors have to cope with a large dynamic range in the images (one to 104 photons/pixel). An additional challenge is the European XFEL machine: an Electron bunch train with 10 Hz repetition rate, consisting of up to 3,000 bunches with a 200 ns spacing. This means that recorded images have to be stored inside the pixel during the bunch trains and read out between bunch trains. In order to meet these requirements, the European XFEL has launched 3 detector development projects. The AGIPD project is a collaboration between DESY, PSI and the Universities of Bonn and Hamburg. The goal is a 1000 × 1000 pixel detector, with 200 μm pixel size and a central hole for the primary beam. The ASIC operates in charge integration mode: the output of each pixel preamplifier is proportional to the charge from the sensor generated by the X-rays. The input stage of the pixel cells will have dynamically adjustable gains. The output signal is stored in an analogue pipeline, which has to be a compromise between noise performance and the number of images. 200 to 400 images have to be readout and digitized in the 99.4 ms long bunch gap. The detector will be built of 2×8 fully depleted monolithic silicon sensors with a 2×8 array of CMOS readout chips bump-bonded to these. The interface electronics is designed to process 400 images in 99 msec, without compromising single photon sensitivity or the full dynamic range. Since the ASIC is the linchpin of the project, several MPW runs to test the different aspects in terms of radiation hardness, noise and adaptive switching are submitted. We will give a general overview and report on the current status.