Rad-Hard High-Dynamic-Range TEM Direct Detector

C55-18a-270598Although direct detection technology delivers substantially better image quality for transmission electron microscopy (TEM), its limited dynamic range and radiation sensitivity generally preclude its use for a variety of TEM applications. At present, direct detection is well-suited for biological cryo-EM, where illumination is relatively uniform and the electron exposure rate is limited. However, many structural biology experiments make use of lower magnifications to acquire large areas of multicellular tissues, resulting in high illumination on the camera. This is further compounded when the specimen is stained and thus can tolerate a much higher total exposure. Other experiments, such as micro-crystal electron diffraction (microED) or electron energy loss spectroscopy (EELS), also produce high illumination levels on certain pixels of the camera. In all these cases, high illumination often exceeds the capabilities of current direct detectors. We propose developing a new large-format (4096×4096), high-speed direct detection camera with fully rad- hard pixels and high dynamic range (HDR). This new camera will make use of fully rad-hard design principles that have been successfully developed in the high-energy physics community to prevent most radiation damage on the detector. Additionally, the camera will include simultaneous high-dynamic range (HDR) acquisition to enable capture of high illumination without sacrificing sensitivity to single electrons. During Phase I, Direct Electron will characterize the radiation hardness and lifetime of its new fully rad-hard direct detection pixel design, as implemented in a small ultra-fast 1k×1k sensor and demonstrate the use of this sensor for acquisition of high brightness TEM data, including tomography of stained biological specimens and high-speed microED without the use of a beamstop. In parallel, Direct Electron will identify and evaluate potential hardware solutions for transferring large-readout-area (4k x 4k) data to the end-user computer at very high speed (several-fold higher data rates than any of our current cameras), which will be necessary for the camera system to be developed and implemented in Phase II of this project. Successful development of a fully rad-hard high dynamic range direct detection camera will dramatically expand the capabilities of electron microscopy by significantly increasing both spatial and temporal resolution under high brightness conditions, including large-area tomography of multicellular biological specimens, high-speed microED, and EELS. Such a camera would obsolete the large number of indirect scintillator-coupled cameras currently used for these experiments.