 It also makes sideband mass spectrometry possible, a standard tool of nuclear physics.Gabrielse has also invented a self-shielding superconducting solenoid that uses flux conservation and a carefully chosen geometry of coupled coils to cancel strong field fluctuations due to external sources.The device was responsible for the success of the precise comparison of antiproton and proton, and also enables magnetic resonance imaging (MRI) systems to locate changing magnetic fields from external sources, such as elevators.