Speaker
Description
The Adaptive Gain Integrating Pixel Detector (AGIPD) [1] is a hybrid pixel detector developed to cope with high dynamic range and megahertz repetition rates of the European XFEL. Its adaptive gain mechanism enables simultaneous detection of single-photon events and high-intensity X-ray signals. AGIPD’s adaptive gain combined with its ability to handle the unique time structure of European XFEL’s pulses makes it indispensable for time-resolved X-ray diffraction, spectroscopy, and imaging studies [2].
To ensure reliable and accurate experimental results, the detector’s raw signal must be precisely calibrated (i.e. converted into meaningful physical units) while accounting for variations in detector pixel-to-pixel response and characteristic. The accuracy of the final experimental data depends directly on the precision of the calibration constants used to correct the detector response; higher-quality calibration leads to improved detector performance and enhanced scientific output.
While the calibration methodologies have been developed and validated on single-ASIC systems [3], extending these approaches to the full 1MPixel AGIPD detector (AGIPD1M) introduces additional challenges. Beyond the detector’s scale, system-level electronic effects must be accounted for, necessitating adaptations and novel approaches to certain calibration methods for full-detector implementation. Characterising AGIPD1M’s behaviour requires deriving coefficients from three distinct datasets: dark data, dynamic range scans, and low-intensity fluorescence measurements. The process entails calibrating every memory cell in each pixel across three gain stages, resulting in over $10^9$ calibration parameters. Furthermore, calibration is an ongoing process as calibration constants must be periodically updated to compensate for detector aging, radiation damage, and evolving operational scenarios. The required datasets are acquired at different intervals, ranging from a few hours for dark data to $6-12$ months for dynamic range scans and fluorescence measurements, making calibration a continuous challenge.
To streamline this complex detector calibration and characterisation procedure, a suite of highly automated calibration and characterisation routines has been developed as part of the European XFEL offline calibration framework [4]. Given the vast number of calibration parameters, automated validation methods are essential to ensure the reliability of the calibration process. In this work, we present the implementation of these routines, describe the algorithms used for processing calibration data, and demonstrate their impact on optimising the performance of AGIPD detectors at the European XFEL.
[1] Allahgholi, A., et al. (2019). J. Synchrotron Rad. 26, 74-82.
[2] Sztuk-Dambietz, J., et al. (2024). Front. Phys. 11, 1329378.
[3] Mezza, D., et al. (2022). Nucl. Instrum. and Methods Phys. Res. A 1024, 166078
[4] Schmidt, P., et al. (2024). Front. Phys. 11, 1321524.
| Workshop topics | Applications |
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