Error characterization and calibration of real-time magnetic field measurement systems

Abstract

In synchrotrons at the European Organization for Nuclear Research (CERN), magnetic measurement systems known as B-trains measure the magnetic field in the main bending magnets in real-time, and transmit this signal for the control of the synchrotron’s RF accelerating cavities, magnet power converter and beam monitoring systems. This work presents an assessment of the capabilities and performance of the new FIRESTORM (Field In REal-time STreaming from Online Reference Magnets) system as part of the first phase of commissioning. A short summary of the architecture of the measurement system is provided first, followed by the definition of an error model which can be used to characterize random and systematic errors separately. We present a procedure for the metrological calibration and qualification of the B-trains, including an experimental evaluation of the different error sources for the four new systems being commissioned in the Proton Synchrotron Booster (PSB), Low Energy Ion Ring (LEIR), Proton Synchrotron (PS) and the Extra Low ENergy Antiproton (ELENA) ring. In particular, we discuss a method to calibrate systematic gain and offset errors based on the RF cavity frequency offset needed to center the beam on its theoretical orbit.