“Detector walk” in position-sensitive detectors with biased microchannel plates

Abstract

The spatial resolution of high-accuracy microchannel plate (MCP) detectors has reached the values, where the so-called detector walk (or image blurring) may start to limit any further improvements. Image blurring with gain is studied in detail for detectors incorporating angular-biased MCPs. It was found that the presence of the pore bias at the output MCP results in a variation of the charge footprint position for events with different gains. Events with higher gains are shifted in the direction of the pore bias and the absolute value of this shift is directly proportional to the absolute value of the detector gain. Variation of the detector modal gain from 7.5×106 to 2.5×107 resulted in a ∼100 μm image offset for a 13°-biased MCP positioned at a distance of 8.5 mm from the anode with an accelerating rear field of 75 V/mm. We also extended our previous study of another type of detector walk associated with fluctuations of the accelerating rear field. Image displacements as functions of the rear accelerating field for both 13°- and 19°-biased MCPs were measured and compared with the results of computer simulation based on our charge cloud propagation model presented earlier. A good agreement between the experimental and simulated data verifies the validity of the model for different MCPs.

Monte Carlo simulation of 10B doped thermal neutron sensitive microchannel plate

“…The spatial resolution of the biased nMCP can be estimated as L • tan θ. A bias angle is always adopted in the MCP to prevent the ion feedback, which will lead to the degradation of the photocathode and reduce the lifetime of the MCP [1,16,17]. since the increase of the bais angle is harmful to spatial resolution and detection efficiency, a nMCP with a small bias angle between 1-2 is preferred.…”

Centroiding algorithms and spatial resolution of photon counting detectors with cross-strip anodes

“…It was shown that this asymmetry may result in image distortions along the direction of pore bias 17,18 . However, the same studies indicate that the charge footprint asymmetry is quite small when the distance between the MCP and anode is on the order of only few millimeters (2.2 mm in our current detector).…”

Evaluation of Neutron‐Radiation Tolerance of Lithium Indium Diselenide Semiconductors

“…[6,7] These screens offer a large imaging area, but their spatial resolution is arguably proportional to the thickness of the converter material due to intrinsic light scattering. [8,9] Furthermore, the required CCDs do not offer the timing resolution required to conduct dynamic studies and energy resolved imaging in a reasonable amount of time. [10] A more recent development is the use of 10 B-doped microchannel plates (MCPs) coupled to the Timepix ASIC.…”