Hybrid Superconducting Neutron Detectors

TL;DR

This paper introduces a novel neutron detector using superconducting niobium strips coated with boron, which detects neutrons via nuclear reactions causing superconducting-normal transitions, verified through experiments at a neutron source.

Contribution

It presents a new neutron detection method based on superconducting niobium strips coated with boron, demonstrating effective detection of thermal neutrons with resettable voltage signals.

Findings

Voltage pulses exceeding 40 mV upon neutron irradiation

Detector operates at 8 K below critical current

Potential for high spatial resolution and efficiency

Abstract

A new neutron detection concept is presented that is based on superconductive niobium (Nb) strips coated by a boron (B) layer. The working principle of the detector relies on the nuclear reaction 10B+n $\rightarrow$ $\alpha$+ 7Li , with $\alpha$ and Li ions generating a hot spot on the current-biased Nb strip which in turn induces a superconducting-normal state transition. The latter is recognized as a voltage signal which is the evidence of the incident neutron. The above described detection principle has been experimentally assessed and verified by irradiating the samples with a pulsed neutron beam at the ISIS spallation neutron source (UK). It is found that the boron coated superconducting strips, kept at a temperature T = 8 K and current-biased below the critical current Ic, are driven into the normal state upon thermal neutron irradiation. As a result of the transition, voltage pulses in excess of 40 mV are measured while the bias current can be properly modulated to bring the strip back to the superconducting state, thus resetting the detector. Measurements on the counting rate of the device are presented and the future perspectives leading to neutron detectors with unprecedented spatial resolutions and efficiency are highlighted.