Scintillators for Andor High Energy Detection Cameras

iKon-L HF CCD

*Spatial resolution is given at 10% MTF for the entire system iKon-L HF, 1:1 fibre-optic plate and scintillator at 40 keV. Please note that spatial resolution wil decrease at lower energies.

Zyla HF sCMOS

*Spatial resolution is given at 10% MTF for the entire system Zyla HF, 10:1 fibre optic plate and scintillator at 40 keV. Please note that spatial resolution will decrease at lower energies.

Absorption and Light yield characteristics of inorganic scintillators of interest

Figure 1 - Csl-TI Absorption Characteristics versus incoming x-ray -photon energy and material thickness (source Hamamatsu)

Note: Most of the x-ray photons below 8 keV will ben absorbed by the protection layer before reaching Csl layer.

Figure 2 - Absorption characteristics of YAG:Ce (top) and LuAG:Ce (bottom) vs incoming x-ray photon energy and material thickness (courtesy of Crytur)

Figure 3 - Photon yield characterisitcs of YAG:Ce (top) and LuAG:Ce (bottom) vs incoming x-ray photon energy and material thickness (courtesy of Crytur)

Spectral Matching

The scintillator emission wavelength should be matched to the sensitivity of the detector. Quantum efficiency of typical CCD and sCMOS sensors are shown on Fig. 4 alongside the peak emission wavelength of scintillators of interest.

Figure 4 – Back-illuminated CCD (top left) and front-illuminated sCMOS (top right) typical Quantum Efficiency curves overlapped with peak emission wavelength of relevant x-ray scintillators. Bottom figure shows full spectral response of various scintillators including YAG:Ce & YAG:Ce types (courtesy of Crytur)

Spatial Resolution and Throughput

A single scintillator does not typically simultaneously achieve high spatial resolution and high light throughput. Compromise on the scintillators properties (e.g. thickness) have to be made to favour one aspect over the other or achieve the best balance between the two. The figure below shows an example of a high spatial resolution image obtained with a Zyla-HF sCMOS coupled to a high resolution 20 µm YAG:Ce scintillator and a high throughput 150 µm CsI:Tl scintillator. To achieve similar intensity with the two configurations, the exposure time for the high resolution scintillator had to be 100 times higher than for the high throughput option.

Figure 6 - X-Ray image of a wasp taken with a 40 kv X-ray source, courtesy of Crytur. Left: Zyla-HF fibre coupled to a 20 um YAG:Ce scintillator, 10s exposure time. Right: ZYla-HF fibre-coupled to a 150 um CSl:Tl scintillator, 0.1s exposure time.

Andor 'Fibre-Optic' HF Camera Platforms

 Table 1 - Andor 'fibre-optic coupled' cameras key specifications

Andor 'Fibre-optic' 'HF' Cameras Accessories

Figure 6 - Zyla-HF (left) and iKon-L hf (right) filter and scintillator holders configuration with a 50 x 50 x 4 mm Csl:Tl scintillator; configuration is slightly different to accomodate the circular YAG:Ce and LuAG:Ce scintillators.

Table 2 - Standard scintillator and filter holders for Andor fibre-optic 'HF' platforms (xxx denotes the scintillator thickness) 
* available through CSR - thinner windows carry increased risks of breakage, long-term stress

Q&A

What information should be provided for custom scintillator?