For high-energy applications, the detection efficiency is limited by the thickness of the silicon sensor, which converts the X-ray photons into an electrical charge. The high-energy sensors with increased sensor thicknesses of 1000 µm compensate for the lower absorption efficiency of silicon at high energies.
All silicon sensors are based on DECTRIS' well-established silicon technology and available for all DECTRIS detectors of the MYTHEN2 and PILATUS detector families: from the MYTHEN2 1K to the PILATUS 6M. EIGER detectors are supplied with the standard 450 µm silicon sensors.
For optimal sensitivity at high X-ray energies, the 1000 µm silicon sensors feature enhanced quantum efficiency at energies above 10 keV without compromising the renowned noise-free operation of DECTRIS detectors. For Mo and Ag Kα radiation, the 1000 µm silicon sensor offers excellent quantum efficiency of 76% and 50%, respectively. The enhanced X-ray sensitivity provided by the 1000 µm sensors is ideal for higher-energy applications.
For low-energy applications, DECTRIS offers the 320 µm sensors for MYTHEN2, which enable the lowest possible energy thresholds.
Figure 1 shows the quantum efficiency (QE) for the 320 µm, 450 µm and 1000 µm sensors as a function of energy. The QE values were measured in the PTB laboratory at BESSY II and perfectly match the values predicted by calculation. At high energies, above 10 keV, the QE is limited by the sensor thickness and significantly enhanced for the thicker sensors.
Table 1 gives QE values for the different sensors at typically used X-ray energies.
|Photon energy||320 µm||450 µm||1000 µm|
|5.4 keV (Cr)||94 %||94 %||> 80 %|
|8.0 keV (Cu)||97 %||98 %||96 %|
|12.4 keV (1Å)||72 %||84 %||97 %|
|17.5 keV (Mo)||37 %||47 %||76 %|
|22.2 keV (Ag)||20 %||27 %||50 %|
Tab. 1: Quantum efficiency at typical X-ray energies.