Dectris EIGER 2 - EXTG - Externally Gated Exposure

detector | cong | ntrigger {”value”: 11}
detector | cong | trigger_mode {”value”: ”eies”}
detector | cong | frame_time {”value”: 1.0} ( see 11)
detector | cong | count_time {”value”: 0.9999999} ( see 11)
detector | cong | ntriggers_skipped {”value”: 0}
This exposure congured in the example above will expect 11 trigger input signals and create 10 images.
9.7. EXTG - Externally Gated Exposure
Information #14
The trigger mode ”extg” is only available with DECTRIS EIGER
®
2 X and XE detectors.
Caution #6
Consult the Technical Specications for details about the required electrical characteristics of
the gate signal.
The EIGER2 X and XE detector systems are fully gateable, allowing for measurements down to a few tens of
nanoseconds. In the external gating mode, the detector counts only when the external input signal is high.
This mode allows multiple short exposures to be summed in one image. This functionality is useful to capture
data from rapidly repeating events with a high temporal resolution, such as in pump-probe experiments.
In this documentation a ”gated window” describes the operation, time, and behavior of the detector between
the transition from low to high and back to low of the signal on the external trigger input. Typical times for
”gate windows” are a few tens of ns to a few 100 ns. The delay and jitter of the external gating is well below
100 ns.
The EIGER2 application specic integrated circuit (ASIC) oers two 16 bit counters for each threshold. To allow
maximum exibility, two dierent gating modes (”extg_mode”) are provided: ”single” and ”double”.
The ”double” mode allows to acquire two images with two dierent delay times to be recorded during the
same acquisition by alternating the two counters. For example, this can be used in pump-probe experiments
to acquire an image of the ground state and one of the excited state for each pump-probe cycle in the same
acquisition. This mode is explained in more detail in section
9.7.3.
The ”single” mode connects the two 16 bit counters to form one 32 bit counter (for each threshold). This makes
it possible to take gated acquisitions with a 32 bit dynamic range at the cost of a longer dead time. This mode
is useful if short gating times are needed. All other trigger modes use a feature called auto-summation to
achieve the 32 bit dynamic range while keeping a duty cycle above 99.9% (see section 3.2.3). More information
on the single external gating mode can be found in section 9.7.4.
DECTRIS EIGER
®
2 User Manual v1.8.2 25 | 36