A sealed X-ray microchannel plate imager with CsI photocathode to improve quantitative precision of framing camera

A sealed X-ray microchannel thermal imager as a more efficient and stable alternative to a traditional open structure thermal imager is discussed in Nuclear Instrumentation and Methods in Physics Research.

The static response test shows that the image intensity of the CsI microstrip photocathode is 3.4 times that of the Au microstrip photocathode when illuminated by a non-monochromatic portable X-ray source with high energy photons. The sealed imager discussed here not only enhances the sensitivity and stability of the framing camera, but also has the potential to reduce crosstalks and artifacts, thus further improves the precision of measurement in practice. The gain reductions along the microstrip is found due to the ohmic losses of gating pulse on the microstrip whose thickness is less than the optimum electrical skin depth, for which overcoating microstrip with beryllium is proposed as a solution. When the time interval of applied gating pulses arriving at adjacent microstrips are less than 1 nanosecond, it is found that electro-magnetic crosstalk between the microstrips can affect both the camera gain and the arrival time of the gate pulse. In indirect-drive ICF implosion experiments, the artifact, which is known as a high intensity and spatial variations background, is discovered due to the radiation which arrives at the framing camera detection surface before the microstrips are gated. An additional device is proposed for the camera under consideration to adjust the static electric field and inhibit these effects.

Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 1005, 21 July 2021, 165404