RESUMO
The Adaptive Gain Integrating Pixel Detector (AGIPD) is an X-ray imager, custom designed for the European X-ray Free-Electron Laser (XFEL). It is a fast, low-noise integrating detector, with an adaptive gain amplifier per pixel. This has an equivalent noise of less than 1â keV when detecting single photons and, when switched into another gain state, a dynamic range of more than 104â photons of 12â keV. In burst mode the system is able to store 352 images while running at up to 6.5â MHz, which is compatible with the 4.5â MHz frame rate at the European XFEL. The AGIPD system was installed and commissioned in August 2017, and successfully used for the first experiments at the Single Particles, Clusters and Biomolecules (SPB) experimental station at the European XFEL since September 2017. This paper describes the principal components and performance parameters of the system.
RESUMO
Imaging experiments at the European X-ray Free Electron Laser (XFEL) require silicon pixel sensors with extraordinary performance specifications: doses of up to 1â GGy of 12â keV photons, up to 10(5) 12â keV photons per 200â µm × 200â µm pixel arriving within less than 100â fs, and a time interval between XFEL pulses of 220â ns. To address these challenges, in particular the question of radiation damage, the properties of the SiO(2) layer and of the Si-SiO(2) interface, using MOS (metal-oxide-semiconductor) capacitors manufactured on high-resistivity n-type silicon irradiated to X-ray doses between 10â kGy and 1â GGy, have been studied. Measurements of capacitance/conductance-voltage (C/G-V) at different frequencies, as well as of thermal dielectric relaxation current (TDRC), have been performed. The data can be described by a dose-dependent oxide charge density and three dominant radiation-induced interface states with Gaussian-like energy distributions in the silicon band gap. It is found that the densities of the fixed oxide charges and of the three interface states increase up to dose values of approximately 10â MGy and then saturate or even decrease. The shapes and the frequency dependences of the C/G-V measurements can be quantitatively described by a simple model using the parameters extracted from the TDRC measurements.