A 13 cm × 13 cm size mercuric iodide (HgI2) imager was tested for high (MeV) energy X-ray imaging with a 6 MeV
Betatron and a 4 MeV Linac x-ray source, and the data were compared to those measured at diagnostic (keV) energies.
The 127 μm pixel size imager gave excellent resolution, with a MTF (modulation transfer function) of 45% at the
Nyquist frequency, similar to that of measured at diagnostic (keV) energies. The sensitivity of the imager was measured
using a 1 mm thick Cu and a 0.5 mm thick Ta buildup plate, placed on the top electrode of the HgI2 layer and also
without any buildup plate. The highest signal levels were obtained without a buildup plate.
The imager can also capture fluoroscopic images at up to 15 fr/sec in the full resolution mode, and at up to 30 fr/sec
with 2 × 2 pixel binning. . With this imager, small steel objects were clearly visible behind a 1/8" thick steel plate.
These experiments with high energy x-rays, demonstrate that HgI2 imagers can be used, not only for the diagnostic
energy range, but also for the MeV energy range. Moreover the same imager can be used for dual energy (keV and
MeV) imaging for medical, NDE (non destructive evaluation) and homeland security applications.