A translating coil sensor measured a solenoid’s field profile and reconstructed its magnetic axis in a single scan. The single peer-reviewed instrument study tested a prototype for CERN’s electron-cooler upgrade and achieved about 100 micrometers of repeatability at its ends. Performance varied along the magnet, and the experiment establishes a measurement tool rather than a completed accelerator upgrade.
A moving induction-coil sensor reconstructed the magnetic axis of a prototype solenoid while measuring its field along the magnet. A solenoid is a coil-based magnet used to guide particle beams. The test took place on a prototype for an electron-cooler upgrade at CERN, the European particle-physics laboratory. Electron cooling requires close alignment between the particle trajectory and magnetic-field direction.[1]
The instrument used a sensor built on a 22-layer printed circuit board. A laser tracker recorded its position as it moved through the magnet opening. Induced voltages supplied magnetic-flux measurements. Researchers represented the field with cylindrical harmonics, a mathematical expansion constrained by Maxwell’s equations, and compared that reconstruction with a simpler polynomial approach. Deliberate sideways shifts tested how well it recovered changes in the axis.[1]
The harmonic reconstruction gave better accuracy and linearity in the tested configurations. Magnetic-axis repeatability was approximately 100 micrometers at the solenoid’s ends and poorer in central regions. In this single peer-reviewed instrument study, manual sensor movement and available readout channels also limited the implementation. The experiment validates a prototype measurement approach; it does not establish operational gains from a completed accelerator upgrade.[1]
