10.1088/1367-2630/11/4/043013

Abstract:
Neutrons have zero net electrieal charge and ean thus penetrate deeply into matter, but their intrinsie magnetie moment makes them highly sensitive to magnetie fields. These properties have been eombined with radiographie (2D) and tomographie (3D) imaging methods to provide a unique teehnique to probe macroscopic magnetic phenomena both within and around bulk matter. Based on the spin-rotation of a polarized neutron beam as it passes through a magnetic field, this method allows the direct, real-space visualization of magnetic field distributions. t has been used to investigate the Meissner effect in a type I (Pb) and a type TI (YBCO) superconductor, flux trapping in a type I (Pb) superconductor, anel the electromagnetic field associated with a direct current fiowing in a solenoid. The latter results have been compared to predictions caleulatecl using the Biot-Savart law and have been found to agree weil.