Radiation transport simulations were used to analyse neutron imaging with the current-biased kinetic inductance detector (CB-KID). The PHITS Monte Carlo code was applied for simulating neutron, 4He, 7Li, photon and electron transport, 10B(n,α)7Li reactions, and energy deposition by particles within CB-KID. Slight blurring in simulated CB-KID images originated from 4He and 7Li ions spreading out in random directions from the 10B conversion layer in the detector prior to causing signals in the X and Y superconducting Nb nanowire meander lines. 478 keV prompt gamma rays emitted by 7Li nuclei from neutron-10B reactions had negligible contribution to the simulated CB-KID images. Simulated neutron images of 10B dot arrays indicate that sub 10 μm resolution imaging should be feasible with the current CB-KID design. The effect of the geometrical structure of CB-KID on the intrinsic detection efficiency was calculated from the simulations. An analytical equation was then developed to approximate this contribution to the detection efficiency. Detection efficiencies calculated in this study are upper bounds for the reality as the effects of detector temperature, the bias current, signal processing and dead-time losses were not taken into account. The modelling strategies employed in this study could be used to evaluate modifications to the CB-KID design prior to actual fabrication and testing, conveying a time and cost saving.
A. Malins, M. Machida, T. D. Vu, K. Aizawa & T. Ishida
Nuclear Instruments and Methods in Physics Research A 953, 163130 (2020)