EIGER2 ASIC
The EIGER2 readout ASIC combines the advanced features of DECTRIS’ earlier readout ASICs, PILATUS3 and EIGER, and combines them with novel features that provide exciting new detection capabilities.
The DECTRIS Instant Retrigger® technology, introduced with PILATUS3, achieves superior count rates and unsurpassed dynamic range. The continuous readout, first featured on EIGER detectors, enables a practically dead-time free readout of EIGER2 for maximum duty cycle at high frame rates.
In addition, EIGER2 introduces two energy-discriminating thresholds per pixel allowing to measure images at two different threshold energies simultaneously. Moreover EIGER2 brings new advanced capabilities, such as new gating modes for pump-probe experiments, 8-bit readout for increased time-resolution, and Lines Region-of-Interest (ROI) readout for unmatched framerates. All these features are enabled by the technology-leading design of the electronic readout circuit integrated inside the 75 µm x 75 µm small pixels of the EIGER2 ASIC (compare figure).
Silicon and CdTe compatible for high efficiency
The EIGER2 ASIC is compatible with both silicon and cadmium telluride sensors to offer optimal quantum efficiency from soft up to hard X-ray energies.
Two thresholds for energy-selective detection
EIGER2 offers two energy-discriminating thresholds, enabled by two comparator stages in each pixel (Cmp 1, 2). This makes it possible to record images for two different energy thresholds simultaneously. While the lower threshold allows suppression of fluorescence background, the upper threshold can be employed to detect and remove high-energy background (cosmics, higher harmonics). The images of both thresholds can be read out separately or in difference mode (energy window).
DECTRIS Instant Retrigger® for high count rates
Instant Retrigger technology that was first introduced for PILATUS3 detectors enables EIGER2 to measure up to a very high count rate of 107 counts/s/pixel with high precision, with an Instant retrigger unit for each threshold preventing the paralyzation of the counting process at high count rates.
Continuous readout for fast loss-free image acquisition
The EIGER2 ASIC enables maximum duty cycle and fast loss-free imaging even at kilohertz frame rates by a novel feature: four digital counters per pixel, two for each energy discriminating threshold (Counters 1a and 1b, and, Counters 2a and 2b). With this architecture, EIGER2 can simultaneously expose and readout by instantaneously switching between the two 16-bit counters of each threshold. While one counter is active and recording the photon counts of the current image, the photon counts of the previous image are read out from the other counter. In this continuous readout process the EIGER2 ASIC switches between the two counters within less than 100 ns, resulting in practically no deadtime between frames of an image series.
Note: At slow frame rates by default the 16-bit counter values will be automatically summed on the detector control unit into 32-bit images, to obtain a practically unlimited dynamic range (>109 counts).
Gating time down to 100 ns and Double Gating
The counting process on the EIGER2 pixels can be switched on and off with an electronic gate signal for exposure times as short as 100 ns. Moreover, the architecture of two counters per threshold enables the new Double-Gating mode on EIGER2, which allows the acquisition of images at two different delay times in pump-probe type measurements simultaneously within the same exposure series.
