Energy-Resolved Neutron Imaging using a Delay Line Current-Biased Kinetic-Inductance Detector

Abstract

We demonstrate the development of an energy resolved neutron transmission imaging system via a solid-state superconducting detector, called current-biased kinetic-inductance detector (CB-KID). CB-KIDs comprise X and Y superconducting Nb meanderlines with Nb ground plane and a 10B conversion layer, which converts a neutron to two charged particles. High-energy charged particles are able to create quasi-particle hot spots simultaneously in the X and Y meander lines, and thus, the local Cooper pair density in meander lines is reduced temporary. When DC-bias currents are fed into the meander lines, double pairs of voltage pulses are generated at the hot spots and propagate toward both ends of the meander lines as electromagnetic waves. The position of the original hot spot is determined by a difference in arrival times of the two pulses at the two ends for X and Y meander lines, independently. This is so-called the delay-line method, and allows us to reconstruct the two-dimensional neutron transmission image of a test sample with four signal readout lines. We examined the capability of high spatial and energy (wavelength) resolved neutron transmission imaging over the sensor active area of 15 ×15 mm2 for various samples, including biological and metal ones. We also demonstrated the capability for the Bragg edge transmission and an energy-resolved neutron image in which stainless-steel specimens were discriminating from other specimens.