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Neutron imaging is one of the key technologies for non-destructive transmission testing. Recent progress in the development of intensive neutron sources allows us to perform energy-resolved neutron imaging with high spatial resolution. Substantial efforts have been devoted to developing a high spatial and temporal resolution neutron imager. We have been developing a neutron imager aiming at conducting high spatial and temporal resolution imaging based on a delay-line neutron detector, called the current-biased kinetic-inductance detector, with a conversion layer 10B. The detector allowed us to obtain a neutron transmission image with four signal readout lines. Herein, we expanded the sensor active area, and improved the spatial resolution of the detector. We examined the capability of high spatial resolution neutron imaging over the sensor active area of 15 × 15 mm2 for various samples, including biological and metal ones. We also demonstrated an energy-resolved neutron image in which stainless-steel specimens were discriminating of other specimens with the aid of the Bragg edge transmission.

We are developing a new type of the neutron imager based on a superconducting neutron detector. We previously succeeded in constructing and demonstrating neutron detection capability of a superconducting current-biased kinetic inductance detector (CB-KID). In order to improve the spatial resolution and detection efficiency, the characteristics of a superconducting neutron detector have been studied systematically in the present work. As an extension of studying the characteristics of neutron detector, we investigated temperature dependence of neutron signal such as propagation velocity and the signal amplitude as a function of time of flight (ToF) with temperature. We consider that it is important to understand the temperature dependence of the signal to improve the spatial resolution and detection efficiency of a superconducting neutron detector.

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Abstract. In our preceding works, we demonstrated successful neutron detection using a superconducting current-biased kinetic inductance detector (CB-KID), which is composed of two Nb-based superconducting meanderlines and the 10 B neutron absorption layer. The CB-KID with a 10 B absorption layer outputs the voltage pulses when it is irradiated by pulsed neutrons. We expected that the voltage V is proportional to a product of the bias current Ib and a time derivative of the local kinetic inductance dΔLk/dt, and a pair of signals propagate along the Nb stripline as an electromagnetic wave at a certain fraction of the light velocity c toward end electrodes. It still remains to be revealed why the signal voltage shows such a continuum in the histogram of the signal height even if the incident energy of the light ion is apparently monochromatic. In the present work, we investigated the distribution of the height and width of the signal. We found a clear correlation between height and width, which might be a key of understanding the operating principle of our detector. We consider that the origin of the signal distribution is due to the positional dependence of the light ion bombardment with respect to the meandering Nb nanowire.