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An in situ procedure for calibrating equivalent magnetic area and rotation radius of rotating coils is proposed for testing accelerator magnets shorter than the measuring coil. The procedure exploits measurements of magnetic field and mechanical displacement inside a reference quadrupole magnet. In a quadrupole field, an offset between the magnet and coil rotation axes gives rise to a dipole component in the field series expansion. The measurements of the focusing strength, the displacement, and the resulting dipole term allow the equivalent area and radius of the coil to be determined analytically. The procedure improves the accuracy of coils with large geometrical irregularities in the winding. This is essential for short magnets where the coil dimensions constrain the measurement accuracy.Experimental results on different coils measuring small-aperture permanent magnets are shown. (2012) Geneva, Switzerland Published in Review of Scientific Instruments CERN-ATS-2012-018 February 2012Abstract REVIEW OF SCIENTIFIC INSTRUMENTS 83, 013306 (2012) In situ calibration of rotating sensor coils for magnet testing An in situ procedure for calibrating equivalent magnetic area and rotation radius of rotating coils is proposed for testing accelerator magnets shorter than the measuring coil. The procedure exploits measurements of magnetic field and mechanical displacement inside a reference quadrupole magnet. In a quadrupole field, an offset between the magnet and coil rotation axes gives rise to a dipole component in the field series expansion. The measurements of the focusing strength, the displacement, and the resulting dipole term allow the equivalent area and radius of the coil to be determined analytically. The procedure improves the accuracy of coils with large geometrical irregularities in the winding. This is essential for short magnets where the coil dimensions constrain the measurement accuracy. Experimental results on different coils measuring small-aperture permanent magnets are shown.

Abstract-The metrological characterization in a static magnetic field of a transducer based on ferrimagnetic resonance for realtime markers in particle accelerators is reported. The transducer is designed to measure the magnetic field with a precision of 10 T. A case study on the new real-time field monitoring system for the CERN accelerators highlighting the performance of the new ferrimagnetic transducer is described. Preliminary experimental results of the characterization for static fields are discussed.