Multiplexing readout method based on switch arrays for position sensitive thermal neutron detectors

Abstract

To address complexities arising from the increased number of readout channels in large scale neutron detection or imaging systems, a multiplexing readout method is introduced. The proposed method can greatly reduce the scale and cost of the readout electronics. To evaluate the readout method, a prototype involving a front-end circuit and a signal multiplexed circuit for detectors such as multiwire proportional chamber (MWPC), gaseous electron multipliers (GEM) and micro-channel plates (MCP) is evaluated in the laboratory. The multiplexing circuit consists of a switch array and a high speed analog to digital converter (ADC). By controlling the switch timing, multi-channel signals can be readout through only one ADC channel, thereby reducing the number of channels required for readout. Furthermore, the readout speed can be adjusted by changing the switching frequency. The results show that the multiplexing readout method is feasible, and the position resolution for thermal neutron detectors is good. The evaluation board is used to simulate the MWPC detector with 2 mm spacing and a position resolution of 35 μm is obtained with event rate up to 2 MHz. Besides, joint test with a thick gaseous electron multipliers (TGEM) detector with 0.8 mm spacing yields a position resolution of about 400 μm.