  Neutron imaging is one of the most powerful tools for nondestructive
inspection owing to the unique characteristics of neutron beams, such as high
permeability for many heavy metals, high sensitivity for certain light
elements, and isotope selectivity owing to a specific nuclear reaction between
an isotope and neutrons. In this study, we employed a superconducting detector,
current-biased kinetic-inductance detector (CB-KID) for neutron imaging using a
pulsed neutron source. We employed the delay-line method, and high spatial
resolution imaging with only four reading channels was achieved. We also
performed wavelength-resolved neutron imaging by the time-of-flight method for
the pulsed neutron source. We obtained the neutron transmission images of a
Gd-Al alloy sample, inside which single crystals of GdAl3 were grown, using the
delay-line CB-KID. Single crystals were well imaged, in both shapes and
distributions, throughout the Al-Gd alloy. We identified Gd nuclei via neutron
transmissions that exhibited characteristic suppression above the neutron
wavelength of 0.03 nm. In addition, the ^{155}Gd resonance dip, a dip structure
of the transmission caused by the nuclear reaction between an isotope and
neutrons, was observed even when the number of events was summed over a limited
area of 15 X 12 um^2. Gd selective imaging was performed using the resonance
dip of ^{155}Gd, and it showed clear Gd distribution even with a limited
neutron wavelength range of 1 pm.
