No abstract

The designs of a compact, fast CCD (cFCCD) camera, together with a resonant soft x-ray scattering endstation, are presented. The cFCCD camera consists of a highly parallel, custom, thick, high-resistivity CCD, readout by a custom 16-channel application specific integrated circuit to reach the maximum readout rate of 200 frames per second. The camera is mounted on a virtual-axis flip stage inside the RSXS chamber. When this flip stage is coupled to a differentially pumped rotary seal, the detector assembly can rotate about 100°/360° in the vertical/horizontal scattering planes. With a six-degrees-of-freedom cryogenic sample goniometer, this endstation has the capability to detect the superlattice reflections from the electronic orderings showing up in the lower hemisphere. The complete system has been tested at the Advanced Light Source, Lawrence Berkeley National Laboratory, and has been used in multiple experiments at the Linac Coherent Light Source, SLAC National Accelerator Laboratory.

A 1M-and a 4M-pixel monolithic CMOS active pixel sensor with 9.5×9.5 µm 2 pixels have been developed for direct imaging in transmission electron microscopy as part of the TEAM project. We present the design and a full characterisation of the detector. Data collected with electron beams at various energies of interest in electron microscopy are used to determine the detector response. Data are compared to predictions of simulation. The line spread function measured with 80 keV and 300 keV electrons is (12.1 ± 0.7) µm and (7.4 ± 0.6) µm, respectively, in good agreement with our simulation. We measure the detection quantum efficiency to be 0.78±0.04 at 80 keV and 0.74±0.03 at 300 keV. Using a new imaging technique, based on single electron reconstruction, the line spread function for 80 keV and 300 keV electrons becomes (6.7 ± 0.3) µm and (2.4 ± 0.2) µm, respectively. The radiation tolerance of the pixels has been tested up to 5 Mrad and the detector is still functional with a decrease of dynamic range by ≃ 30 %, corresponding to a reduction in full-well depth from ∼39 to ∼27 primary 300 keV electrons, due to leakage current increase, but identical line spread function performance.

a b s t r a c tMonolithic CMOS pixel sensors offer unprecedented opportunities for fast nano-imaging through direct electron detection in transmission electron microscopy. We present the design and a full characterisation of a CMOS pixel test structure able to withstand doses in excess of 1 Mrad. Data collected with electron beams at various energies of interest in electron microscopy are compared to predictions of simulation and to 1.5 GeV electron data to disentagle the effect of multiple scattering. The point spread function measured with 300 keV electrons is ð8:1 AE 1:6Þ mm for 10 mm pixel and ð10:9 AE 2:3Þ mm for 20 mm pixels, respectively, which agrees well with the values of 8.4 and 10:5 mm predicted by our simulation.

A cluster imaging technique for Transmission Electron Microscopy with a direct detection CMOS pixel sensor is presented. Charge centre-of-gravity reconstruction for individual electron clusters improves the spatial resolution and thus the point spread function. Data collected with a CMOS sensor with 9.5×9.5 µm 2 pixels show an improvement of a factor of two in point spread function to 2.7 µm at 300 keV and of a factor of three in the image contrast, compared to traditional bright field illumination.