Report on future detector requirements at ESRF

of projections. A dynamic range larger than 13 bits is needed for 2k pixels and it grows as √N
as the number of pixels increases.
The scintillator response should not degrade the required dynamic range (afterglow effects,
emission from substrate).
Linearity:
The deviation from linearity should be less than 0.5% on the whole dynamic range (current
value is better than 2% with the FReLoN camera).
Flux on detector:
The flux for imaging is typically 10 10 to 10 13 photons/s/mm 2 . The absolute maximum on
detector is estimated to 10 15 photons/s/mm 2 (flux obtained on ID22 with present
configuration in pink beam – should be less on NINA, which will be longer).
Other comments:
Data acquisition and storage: Data correction and compression techniques built in the
detector may be useful. Data compression may even present losses provided that they are well
defined and adapted to quantitative volume imaging.
Radiation hardness and stability: In certain cases, the detectors will need to operate under
heavy irradiation and heat load conditions. Both scintillators and optics may need to be stable
and radiation tolerant, even compromising performance in some cases.
Existing detectors
ID19, ID22 and ID22NI are currently using FReLoN cameras with scintillators and several
optical couplings giving pixel sizes from 0.2 µm to 30 µm.
Required detector
Required detector is a 2D sensor coupled via optical set-up to scintillator. The concept of
FReLoN camera as general-purpose camera is extremely convenient: same imaging sensor for
all optical configurations.
Main required improvements
The main expected improvements are efficiency, both in detection and time (read out as well
as fast shuttering scheme to shorten the smallest possible exposure time). Then, the number of
pixels, i.e. the field of view for a given spatial resolution, should be increased, preserving
other specifications. Expected improvements are summarised below:
Short
term
Medium term Long term
Parameter Efficiency
Efficiency
+ Field of View
Efficiency + Field of View
+ Speed
DQE 50% at 20 keV with 1µm resolution
Number of pixels 4kx4k 8kx8k
Dynamic range > 13 bits (imposed by tomography needs)
> 95% @ 100ms exposure
Duty cycle
mechanical shutter
impossible
Maximum frame
> 1000 fps for 1kx1k pixels
rate
> 100 fps for 8kx8k pixels
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