Large area sensing arrays for detection of thermal neutrons

Abstract

Developments of flexible detection arrays suggest that portable robust detectors are indeed possible. A large area flexible array promises a large capture cross section in a light weight rugged format suitable for deployment at ports of entry.The approach for this detector uses a high neutron-capture cross section layer, such as lOB, which captures incident thermal neutrons, and emits energetic ionizing charged particles. These ionizing particles are sensed using an integrated diode. The resulting charge is then amplified via a low-noise thin film transistor amplifier. We present a low-noise optimized active pixel sensor (APS) design which can be implemented in either a low temperature InGaZnO or an a-Si:H thin film transistor (TFT) process compatible with plastic substrates. Here, we also present a detectable alpha particle response with our dual stage APS design in combination with an externally connected commercial PIN diode. Furthermore, we discuss detector and array modeling which will further aid in future designs.

TFT‐based, multi‐stage, active pixel sensor for alpha particle detection

“…A TFT-based neutron detector allows the pin photodiodes to be arrayed into a large sheet-like detector, where each pixel has its own TFT readout circuitry. Earlier TFT-based readout approaches for neutron detection used a conventional active pixel sensor (APS) design very similar to that commonly used in image sensors [7][8][9]. However, this earlier approach was observed to lack the required sensitivity and found to be unable to reliably detect alpha particles consistent with neutron strikeswith the output response barely recognisable above the noise floor [9].…”

“…Earlier TFT-based readout approaches for neutron detection used a conventional active pixel sensor (APS) design very similar to that commonly used in image sensors [7][8][9]. However, this earlier approach was observed to lack the required sensitivity and found to be unable to reliably detect alpha particles consistent with neutron strikeswith the output response barely recognisable above the noise floor [9]. The new approach presented in this Letter solves this sensitivity issue, using a new multi-stage APS design with ∼ 5 × greater gain combined with the new ability to return the TFT amplifier circuit to a high-gain state immediately following a detected event.…”