Megapixels @ Megahertz – The AGIPD high-speed cameras for the European XFEL

Abstract

The European XFEL is an extremely brilliant Free Electron Laser Source with a very demanding pulse structure: trains of 2700 X-Ray pulses are repeated at 10 Hz. The pulses inside the train are spaced by 220 ns and each one contains up to 10 12 photons of 12.4 keV, while being ≤ 100 fs in length. AGIPD, the Adaptive Gain Integrating Pixel Detector, is a hybrid pixel detector developed by DESY, PSI, and the Universities of Bonn and Hamburg to cope with these properties.It is a fast, low noise integrating detector, with single photon sensitivity (for E γ 6 keV) and a large dynamic range, up to 10 4 photons at 12.4 keV. This is achieved with a charge sensitive amplifier with 3 adaptively selected gains per pixel. 352 images can be recorded at up to 6.5 MHz and stored in the in-pixel analogue memory and read out between pulse trains. The core component of this detector is the AGIPD ASIC, which consists of 64 × 64 pixels of 200 µm × 200 µm. Control of the ASIC's image acquisition and analogue readout is via a command based interface. FPGA based electronic boards, controlling ASIC operation, image digitisation and 10 GE data transmission interface AGIPD detectors to DAQ and control systems.An AGIPD 1 Mpixel detector has been installed at the SPB 1 experimental station in August 2017, while a second one is currently commissioned for the MID 2 endstation. A larger (4 Mpixel) AGIPD detector and one to employ Hi-Z sensor material to efficiently register photons up to E γ ≈ 25 keV are currently under construction.

Membrane protein megahertz crystallography at the European XFEL

“…The limited size, however, of the currently installed AGIPD makes accurate spot location and indexing for samples with very large cells difficult and may preclude collection of high-resolution data. A 4-megapixel AGIPD is currently in the production stage for crystallography applications 16 .…”

“…Note that the repetition rate of the XFEL is not the only limitation for the rate of data collection at MHz XFELs. Currently, the fastest X-ray detector is the newly developed Adaptive Gain Integrating Pixel Detector (AGIPD), which can collect up to 352 images per train (potentially storing 3520 images per second) 15,16 .…”

Fast digital lossy compression for X-ray ptychographic data

“…Some HPADs developed for XFEL applications include per-pixel capacitors on the ASIC to store the charge Q for up to eight frames at a burst frame rate up to 10 MHz (Philipp et al, 2016), or 352 frames at a burst frame rate of 6.5 MHz (Henrich et al, 2011), followed by digitization of the charge on each capacitor and subsequent digital transfer of the detected frames. However, the maximum continuous frame rate in these detectors is no higher than 16 kHz (Allahgholi et al, 2019), or 20 kHz as anticipated by near-term extension of the ePix detectors (Blaj et al, 2016). The common bottleneck limiting frame rate in charge-integrating HPADs is data bandwidth (Graafsma et al, 2016), and it can limit bandwidth in photon-counting detectors as well.…”

On the use of multilayer Laue lenses with X-ray free electron lasers

“…This structure was printed directly on a 200 m diamond wafer and placed close to the focal plane. It was placed downstream of the MLL focus so that a highly magnified image of this structure was projected on the AGIPD (Adaptive Gain Integrating Pixel Detector) [27] detector. AGIPD is high dynamic range pixel array detector with a 4.5 MHz frame rate.The projection image was used to fine tune the alignment, correct the astigmatism (observable as a different magnification of the image in the horizontal and vertical directions) and to determine the focal plane.…”