Magnet strength measurement in circular accelerators from beam position monitor data

Recent measurements of resonance terms suggested the extension of the existing technique to measure magnet strengths from turn-by-turn beam position monitor data. This article describes the algorithm to infer the magnet strength from the variation along the ring of the resonance terms and reports on the first measurement. Both the algorithm and the software written for the analysis of the data can be particularly useful in the commissioning period of an accelerator in order to find magnets with wrong strengths or polarities as well as magnets with large magnetic errors.