We developed a neutron transmission imager based on a superconducting current-biased kinetic inductance detector (CB-KID). The CB-KID comprises X and Y meanderlines and a 10B conversion layer for neutrons. A 4He or 7Li ion from the 10B(n, α)7Li reaction creates two hot spots in both the X and Y meanders. A pair of electromagnetic-wave pulses of opposite polarities propagate toward the ends of meanderlines. The position of the nuclear reaction point can be evaluated from a difference in arrival timestamps of the two pulses at the two ends. We used a set of analog signal discriminators with fixed thresholds and a time-to-digital converter (TDC) with 1-ns time resolution to recover the signals from 25-Hz pulsed neutrons of J-PARC. The energy-integrated spatial resolution reached 22 μm. Further improvements in spatial resolution can be achieved by using a pair of CB-KIDs to compensate the randomness of the emitted direction of light ions from the 10B reaction. PHITS (Particle and Heavy Ion Transport code System) is a Monte Carlo particle transport simulation code developed to deal with the transport of all particles over wide energy ranges, using several nuclear reaction models and nuclear data libraries. PHITS simulations demonstrated that the neutron imaging can be enhanced appreciably with two CB-KIDs.
This work is supported by Grant-in-Aid for Scientific Research (A) No.16H02450 from JSPS. The devices were fabricated in the clean room for analog-digital superconductivity (CRAVITY). This work is supported of MLF program of J-PARC (Proposal No. 2016B0012, 2017A0011, 2017B0014, 2018A0109, No. 2018P0201, No. 2019A0004).
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|Less than 5 years of experience since completion of Ph.D||N|
|Student (Ph.D., M.Sc. or B.Sc.)||N|