Current-Biased Transition Edge Detector of [Formula Omitted] Nanowires for Neutrons: Imaging by Scanning Laser

The superconducting [Formula Omitted] nanowire detector is biased by a current by a battery-class low voltage, and uses the nuclear reactions with a single neutron and the [Formula Omitted] contained in [Formula Omitted]. The [Formula Omitted] detector consists of a 200-nm-thick [Formula Omitted] thin film meander structure of 3 [Formula Omitted] line width protected by 300-nm-thick SiO layer. We use enriched boron [Formula Omitted] to enhance the sensitivity. The thermal energy of 2.3 MeV released by the reaction [Formula Omitted] gives 1.83 MeV to [Formula Omitted] and 0.47 MeV to [Formula Omitted]. The energy dissipation in a restricted space causes a local resistive state in the [Formula Omitted] wire, which yields a subtle change in bias current. Through a mutual inductance connected in series with current-biased detector, we are able to measure the event as a voltage pulse. The position-dependent response of the [Formula Omitted] detector is investigated by scanning a focused laser spot with the aid of an XYZ piezo-driven stage and an optical fiber with a focusing lens. A clear two-dimensional imaging pattern of the sensor signal well corresponds to the detector geometry. According to our results, the inhomogeneity and position-sensitive nature of the detector are supposed to be critical in governing the detection efficiency of the current-biased transition edge detector, which works only in the narrow temperature regime near [Formula Omitted].